34th Meeting of the section Atomic Molecular and Optical Physics (AMO)

October 12 and 13 2010

Program and abstracts

CongresHotel De WereltLunteren

34th Meeting of the sectionAtomic Molecular and Optical Physics (AMO)

Program and abstracts

CongresHotel De WereltLunteren

October 12 and 13 2010

Scientific Commitee:

Giel Berden • Martin van Exter • Ronnie Hoekstra

Gert ‘tHooft • Servaas Kokkelmans • Leo Meerts

Herman Offerhaus • Robert Spreeuw • Peter van der Straten

Wim Vassen • Caspar van der Wal

This meeting is organized under the auspices of the NNV-section Atomic, Molecular and Optical Physics,

with financial support of the Dutch Science Foundation and the Foundation FOM.

The program is compiled by:

Herman Offerhaus

Peter van der Straten

Conference coordination: Erna Gouwens (RU)

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Tuesday 12 October 2010

10.00 Arrival, registration

10.40 Opening by the chair man of the section AMO Wim Vassen

10.45 I1 Nikolay I. Zheludev (University of Southampton, United Kingdom

“Seeing beyond the cloak: active, controllable and quantum metamaterials”

11.30 Short lectures: (Europa room) chair Herman Offerhaus

O1 Frerik van Beijnum (Leiden University)

“Evanescent waves in extraordinary optical transmission”

O2 Omar El Gawhary (Delft University of Technology)

“The anomalous relation between localization and paraxiality of

pseudo-nondriffracting fields”

O3 Marko Spasenovic (Fom Institute AMOLF)

“Bends in plasmonic nanowire waveguides”

O4 Aurèle J.L. Adam (Delft University of Technology)

“Measurement of the terahertz magnetic near field of a split-ring resonator”

12.30 Lunch

14.00 I2 Silke Ospelkaus (Max Planck Institut für Quantenoptic, Garching Germany)

“Ultracold polar molecules near quantum degeneracy”

14.45 Short lectures: (Europa room) chair Peter van der Straten

O5 Denis D. Arslanov (Institute for Molecules and Materials,

Radboud University Nijmegen)

“Optical parametric oscillator based off-axis integrated cavity output

spectroscopy for real time breath monitoring”

O6 Sadia Bari (Atomic Physics KVI Groningen)

“Peptide dissociation by KeV ions and VUV photons”

O7 Annemieke Petrignani (Max-Planck Institute for Nuclear Physics,

Heidelberg Germany)

“Investigation of highly excited states of H3+ through action spectroscopy:

Is there order in chaos?”

O8 Jelmer J. Renema (Quantop, Niels Bohr Institute, University of Copenhagen,

Denmark)

“Entanglement-assisted atomic clock beyond the projection noise limit”

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Tuesday 12 October 2010

15.45 Coffee/tea break

16.15 Short lectures: (Europa room) chair Martin van Exter

O9 Philip Chimento (Leiden University)

“Plasmonic opical vortex tomography”

O10 Gregorius C.G. Berkhout (Leiden University)

“Efficient sorting of orbital angular states of light”

16.45 Poster Introduction – 1 minute per poster

18.00 Dinner (restaurant) (attach posters)

19.15 Poster presentations (Europa room, please remove posters after

the evening lecture )

21.15 Evening lecture

Deniz van Heijnsbergen (University of Amsterdam, Faculty of Science)

“Opening up the black box called Physical Review Letters:

AMO Physics in the leading physics journal”

POSTERS AND ORAL PRESENTATIONS

Because of the large number of requests for an oral presentation, we were not able to accept all requests.

For oral contributions we have a limited time of 12 minutes per presentation (+ 3 minutes for discussion).

The posters can be placed before or during the dinner.

Before 24.00 hr all posters must be removed.

(The room will be cleaned)

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Wednesday 13 October 2010

08.00 Breakfast (restaurant, please remove luggage from your room)

08.45 I3 Henry Chapman (Centre for Free Electron Laser Science, DESY,

Hamburg Germany)

“Femtosecond coherent X-ray nanocrystallography at LCLS”

09.30 Short talks (Europa room) chair Wim van der Zande

O11 Ruud M. Oldebeuving (University of Twente)

“Separate gain media, an alternative approach to mode-locking”

O12 Tjeerd J. Pinkert (Laser Centre, VU University Amsterdam)

“Widely tunable XUV Combs for high resolution Ramsey spectroscopy”

O13 Vitaly Zhaunerchyk (Institute for Molecules and Materials, Radboud University)

“FLARE: a new THz free electron laser at the Radboud University Nijmegen”

O14 Hector Alvaro Galue (FOM Rijnhuizen)

“IR spectroscopy of ionized corannulene”

10.30 Coffee/tea break

11.00 I4 Ronald Hanson (Kavli Institute of Nanoscience, Delft University of Technology)

“Quantum control of single spins and single photons in diamond”

11.45 Short talks (Europa room) chair Caspar van der Wal

O15 Christian Bonato (Leiden University)

“Towards quantum information processing with quantum dots in polarization-

degenerate oxide-apertured micropillars”

O16 Alok U. Chaubal (University of Groningen)

“Electromagnetically induced transparency in a semiconductor”

O17 Wolfgang Löffler (LION, Leiden University)

“Transport of 3D spatially entangled photons through a hollow-core

photonic crystal fibre”

O18 Sumant S.R. Oemrawsingh (Huygens laboratory, Leiden University)

“DNA scaffolds for quantum optics”

12.45 Lunch

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Wednesday 13 October 2010

13.55 Presentation winner poster award

14.00 Short talks (Europa room) chair Wim Vassen

O19 Johnny Vogels (University of Utrecht)

“The subsonic beam based atom laser”

O20 Antje Ludewig (van der Waals – Zeeman institute University of Amsterdam)

“Feshbach resonances in Fermi mixtures of ultracold 40K”

O21 Rob van Rooij (Laser Center VU University Amsterdam)

“Spectroscopy of a forbidden transition in a Bose-Einstein condensate of 4He and a degenerate Fermi gas of 3HE”

14.45 I5 Servaas Kokkelmans (Eindhoven University of Technology)

“Universal Efimov physics in ultracold gases”

15.30 Finish

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Poster ProgramP1 Far-IR action spectroscopy of strongly bound systems.

J.M. Bakker • FOM RijnhuizenP2 Ultracompact and ultrafast optical switching based on slow light.

Daryl M. Beggs • KVI, University of GroningenP3 ZFEL: A compact, soft X-ray FEL in The Netherlands.

J.P.M. Beijers • Eindhoven University of TechnologyP4 Rydberg Atom Lattices.

R. van Bijnen • University UtrechtP5 Electron transfer in collisions of keV ions with ultracold atoms.

Ina Blank • KVI, Atomic Physics, University of GroningenP6 Cold molecular collisions with merged beams.

Janneke Blokland • Fritz-Haber-Institut der Max-Planck-Gesellschaft, BerlinP7 Characterization of compression and slowdown of a supersonic beam with a shock wave and

evaporative cooling.

P. Bons • University of UtrechtP8 Absence of strong dynamical nuclear polarization from optical driving of donor-bound

electron spins in GaAs.

Alok U. Chaubal • University of GroningenP9 Time-resolved imaging studies of photofragmentation dynamics in cold isolated molecules.

Congsen Meng • Laser Centre and Department of Chemistry, Vrije Universiteit, AmsterdamP10 Damage to plasmid DNA thin films induced by low energy ions.

H.M. Dang • KVI Atomic and Molecular Physics, University of GroningenP11 Ultrafast preparation and detection of arbitrary coherent dark states with donor-bound

electrons in GaAs.

Sergii Z. Denega • University of GroningenP12 High resolution spectroscopy of hydrogen and its isotopomers using VUV synchrotron

radiation and a Fourier-transform spectrometer.

G. D. Dickenson • Vrije Universiteit, AmsterdamP13 Cold molecules by photodissociation of spatially oriented molecules.

Dimitar Dobriko • LaserLAB– and Department of Chemistry VU University AmsterdamP14 Source Temperature Measurements of an Ultracold Electron Source.

W.J. Engelen • Department of Applied Physics, Eindhoven University of TechnologyP15 Coincidence Imaging and Femtosecond Pulse Shaping in Molecular Dynamics studies.

Mohammad Fanood • LaserLAB– and Department of Chemistry, Vrije Universiteit AmsterdamP16 A nanophotonic probe for random cavities.

E.H. Frater • MESA+ Institute for Nanotechnology, University of TwenteP17 Dissociation of free protonated peptides by VUV-photons.

O. Gonzalez-Mangana • KVI Atomic and Molecular Physics, RUGP18 Global optimization of proton-proton decoupling sequences using self-learning algorithms.

L.A.G Grimminck • Radboud University NijmegenP19 3D tumor imaging by self interference fluorescence endoscopy.

Matthijs de Groot • VU AmsterdamP20 Laboratory study of Rayleigh-Brillouin scattering for measuring the winds of the Earth.

Z. Gu • Laser Centre Vrije Universiteit

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P21 Femtosecond imaging and coherent quantum control of molecular photodynamics.

Daniel Irimia • Laser Centre and Department of Chemistry, Vrije Universiteit, AmsterdamP22 Structural analysis of F0F1-ATPase active site mimics by IR spectroscopy.

Sander Jaeqx • FOM institute for Plasma physics Rijnhuizen, NieuwegeinP23 Structure and Magnetization of Transition Metal Oxide Clusters.

J. Jalink • Radboud University NijmegenP24 A Molecular Fountain for High-Resolution Spectroscopy.

Paul Jansen • LaserLaB Vrije Universiteit, AmsterdamP25 Template-stripped buried grating for Plasmonics.

J. Jose • University of TwenteP26 Electron bunch-length measurements using Grating Enhanced Ponderomotive Scattering.

J.H.M.Kanters • Department of Applied Physics, Eindhoven University of TechnologyP27 Molecular hydrogen ions, the proton-electron mass ratio and the proton size.

J.C.J. Koelemeij • LaserLaB, Vrije Universiteit AmsterdamP28 Optical fiber frequency standard networks.

J.C.J. Koelemeij • LaserLaB, Vrije Universiteit AmsterdamP29 Spin drag in an optical trap.

S. B. Koller • Nanophotonics, Utrecht UniversityP30 High Repetition Ultrafast Electron Bunches.

Adam Lassise • Technische Universiteit EindhovenP31 Femtosecond pulse shaping and quantum control in multichannel molecular dynamics studied

by photoelectron-photoion coincidence imaging.

Carl Stefan Lehmann • LaserLAB and Department of Chemistry, Vrije Universiteit, Amsterdam P32 Feshbach resonances in Fermi mixtures of ultracold 40K and 6Li.

A. Ludewig • Van der Waals-Zeeman Instiuut, Universiteit van AmsterdamP33 Coherent Control of Angular Momentum Transfer Dynamics in Resonant One-Photon

Light-Matter Interaction.

D. Malik • Radboud University NijmegenP34 Magnetic effects in FeNi structures codeposited with atom nanolithography.

Thijs Meijer • Eindhoven University of TechnologyP35 Direct frequency comb excitation of the dipole forbidden clock transition in trapped

calcium ions.

J. Morgenweg • LaserLaB, VU AmsterdamP36 Small focus production schemes for observation and control of dipole-dipole interactions

between Rydberg atoms.

R. G. Newell • Van der Waals-Zeeman Instituut, Universiteit van AmsterdamP37 High precision UV measurements in CO, towards a laboratory test of the time-invariance of µ.

Adrian J. de Nijs • LaserLaB Vrije Universiteit, AmsterdamP38 Improving Electromagnetically Induced Transparency in Si: GaAs by Selective Pumping of

Nuclear Spins.

A. R. Onur • University of GroningenP39 Fragmentation chemistry of anionic peptides elucidated by IR spectroscopy.

Jos Oomens • FELIX facility, FOM RijnhuizenP40 Atom-light interactions in plasmonic nanostructures.

D. van Oosten • Debye Institute for NanoMaterials Science,Utrecht University

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Poster ProgramP41 Single-shot femtosecond electron diffraction.

P.L.E.M. Pasman • Eindhoven University of TechnologyP42 Engineering light-matter interaction at the single-photon level.

W. Pfaff • Kavli Insitute of Nanoscience, Delft University of TechnologyP43 Fragmentation and ionization dynamics of Argon clusters upon keV highly charged ion interaction.

J. Postma • KVI Atomic Physics, University of GroningenP44 Momentum imaging studies of dissociative electron attachment to polyatomic molecules – I.

N Bhargava Ram • Current Affiliation : Vrije Universiteit, Amsterdam, NetherlandsP45 Momentum imaging studies of dissociative electron attachment to polyatomic molecules – II.

N Bhargava Ram • Current Affiliation : Vrije Universiteit, Amsterdam, NetherlandsP46 Trapping of 225Ra for electric dipole moment searches.

B. Santra • KVI, University of GroningenP47 Coherent radiation reaction effects in laser-vacuum acceleration.

Smorenburg • T.U. EindhovenP48 Preparation and manipulation of cold molecules.

Dimitrios Sofikitis • Laboratoire Aimé Cotton, CNRSUniversité Paris-Sud, Orsay, FranceP49 New methods for the production and detection of polarized atoms.

Dimitrios Sofikitis • IESL-FORTHHeraklion Crete –GREECE

P50 How oxygen absorbs solar light in a real atmosphere

Frans Spiering • IMM, Radboud Universiteit NijmegenP51 Integrated microspectrometer for biological applications.

A.J. Stephenson • Optical Sciences Group, MESA + Institute for Nanotechnology P52 Spatially resolved excitation of Rydberg atoms on an atom chip.

Atreju Tauschinsky • Universiteit van AmsterdamP53 On-line excited-state laser spectroscopy of trapped short-lived Ra+ Ions.

O.O. Versolato • Kernfysisch Versneller Instituut, University of GroningenP54 Controlling one-dimensional spin motion with state-dependent potentials.

P. Wicke • University of AmsterdamP55 A spectral calibration scheme for terahertz FEL radiation.

F.J.P. Wijnen • Molecular and biophysics, IMM, Radboud University NijmegenP56 Towards coherent lensless X-ray microscopy with a table-top setup.

Stefan Witte • LaserLaB, Vrije Universiteit Amsterdam • JILA, University of Colorado, Boulder, USAP57 Measurements on partially coherent light.

J. Woudenberg • Huygens Laboratory, Leiden UniversityP58 Cavity ringdown absorption spectroscopy of the carbon chain molecules.

D. Zhao • Vrije Universiteit, AmsterdamP59 Detection of volatile compounds in human breath using a femtosecond frequency comb laser.

M.G. Zeitouny • Optics research group, Delft University of TechnologyP60 Switching Casimir forces with Phase Change Materials.

G. Palasantzas • Materials innovation institute M2i and Zernike Institute for Advanced Materials,

University of Groningen

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I1 O1

Seeing beyond the cloak: active, controllable and quantum metamaterials

Nikolay I. Zheludev

University of Southampton, UK

Metamaterials are artificial media struc-

tured on a scale smaller than the wave-

length of external stimuli. Conventional

materials derive an origin for their elec-

tromagnetic characteristics in the proper-

ties of atoms and molecules - metamate-

rials enable us to design our own ‘atoms’

and thus access new ground breaking

functionalities such as invisibility and

imaging with unlimited resolution. The

next stage of this photonic technological

revolution will be the development of

functional metamaterials surpassing

natural media as platforms for optical

data processing and quantum informa-

tion applications. Metamaterials are

expected to have an impact across the

entire range of technologies where elec-

tromagnetic radiation is used, and provi-

de a flexible platform for modelling and

mimicking fundamental physical effects

as diverse as superconductivity and cos-

mology and for templating electromagne-

tic landscapes to facilitate observations of

otherwise difficult to detect phenomena.

We report an overview on our recent

results on achieving new functionalities

in nanostructured photonic metamate-

rials containing nonlinear and active

media such as switchable chalcogenide

glass, carbon nanotubes, graphene, semi-

conductor quantum dots and report on

exciting plasmonic properties of super-

conducting metamaterials.

1] N.I. Zheludev. The road ahead for meta-

materials. Science 328, 582 (2010)

Evanescent waves in extraordinary optical transmission

Frerik van Beijnum1, Chris Smiet1,

Martin van Exter1, Chris Retif2

1 Leiden University2 FOM Instituut AMOLF Amsterdam

The optical transmission through opaque

metal films perforated with arrays of sub-

wavelength size holes is extraordinary

large. We study the relative contribution

of surface plasmons and evanescent opti-

cal waves to this transmission, using a

cleverly-chosen series of arrays with latti-

ce parameters that vary by integer multi-

ples (a=n.a0). We find that the surface

plasmon resonance dominates at distan-

ces larger than 2a0 = 0.9 µm, while the

evanescent waves play an important role

at smaller distances. The figure below

depicts the exceptional behavior of the

n=1 sample in the scaled transmission

spectra (SEM image of the n=2 array in

inset). Additional evidence for the impor-

tant role of evanescent waves is obtained

by angle tuning to larger wavelengths and

from measurements on random patterns

of holes.

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O2 O3

The anomalous relation between localization and paraxiality of pseudo-nondiffracting fields

Omar El Gawhary1, Sergio Severini2

1 Optics Research Group, Delft University

of Technology2 Centro Interforze Studi per le Applicazioni

Militari, Italy

Spatial localization and paraxiality are

properties of an optical field commonly

seen as competing effects: the more spa-

tially confined the field is the more non-

paraxial its propagation will be. Although

this situation reflects perfectly the majo-

rity of cases usually faced in theory and

experiments, there are however few inte-

resting exceptions. In particular, it can be

shown that the class of fields known as

“pseudo-non diffracting” beams, violates

this simple rule. In fact, those fields pre-

sent, under particular conditions, a

reduction in their nonparaxiality when,

at the same time, their transverse sizes

are reduced.

The origin of this effect is described by

discussing few examples and making use

of the concept of degree of paraxiality,

recently introduced in literature[1,2].

[1]. O. El Gawhary and S. Severini, Opt. Lett.,

33, 1360 (2008).

[2].O. El Gawhary and S. Severini, Opt. Comm.,

283, 2481-2487 (2010).

Bends in plasmonic nanowire waveguides

Marko Spasenovic, D. J. Dikken, E. Verhagen,

D. van Oosten, L. Kuipers

FOM Instituut AMOLF Amsterdam

We study bending losses in plasmonic

nanowire waveguides. Using adiabatic

mode conversion, we couple to plasmon

modes of symmetry similar to

Sommerfeld modes, on nanowires as

narrow as 40 nm [1]. Using near-field

microscopy, we study losses in wavegui-

des which make 900 bends. We show that

an intuitive model developed for dielec-

tric waveguides can be used to describe

losses as a function of radius of curvatu-

re. The attenuation due to bending loss

is found to be as low as 0.1 µm-1 for a

curved waveguide with a width of 70 nm

and a radius of curvature as small as

2 µm [2]. For radii of curvature approa-

ching zero, the model breaks down.

Nevertheless, we find more than 50%

transmittance for an abrupt 900 bend.

[1] E. Verhagen, M. Spasenovic, A. Polman, and

L. Kuipers, Phys. Rev. Lett. 102, 203904

(2009).

[2] D. J. Dikken, M. Spasenovic, E. Verhagen,

D. van Oosten, and L. (Kobus) Kuipers,

Opt. Express 18, 16112 (2010).

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11

O4 I2

Measurement of the terahertz magneticnear field of a split-ring resonator

Aurèle J. L. Adam1, Andrew Strikwerda2,

Richard Averitt2, Paul C. M. Planken1

1 Technische Universiteit Delft2 Boston University

We present the first direct measurement

of the magnetic near field of a metama-

terial structure. We have chosen a unit

cell element with a C-shape made from

a thin gold layer on a terbium gallium

garnet magneto-optic crystal (see figure).

Using terahertz time domain spectrosco-

py, we are able to measure the time evo-

lution of the longitudinal component of

the magnetic near field Bz(t) created by

the incident electric field in the vicinity

of the structure (see figure). The magne-

tic near field spectrum peaks at the pre-

dicted resonance frequency of 0.2 THz.

A 2D map of the measured magnetic

field distribution inside the structure will

also be shown. In-plane rotation of the

structure by 180 degrees reverses the sign

of the signal, confirming that we measu-

re the THz magnetic near field.

Ultracold polar molecules near quantum degeneracy

Silke Ospelkaus

Max Planck Institut für Quantenoptic, Germany

Polar molecular quantum gases promise to

open new scientific frontiers and research

directions. Due to their large electric dipole

moment, polar molecules interact via long-

rage and anisotropic interactions. The control

of these interactions provides unique opportu-

nities ranging from the control of ultracold

chemical reactions, applications to quantum

information processing, novel strongly corre-

lated quantum many-body systems to collisio-

nal control on the quantum level with exter-

nal electric and magnetic fieds. Here,we

report on our recent experiments with a

quantum gas of fermionic polar 40K87Rb

molecules. We report the preparation of a

near-quantum degenerate gas of rovibronic

ground state molecules in a single hyperfine

state and in particular in the absolute lowest

quantum state - implementing full control

over all internal molecular quantum degrees

of freedom (electronic, vibrational, rotational

and hyperfine) [1,2]. We discuss experimen-

tal evidence for chemical reactions at ultra-

cold temperatures and show that simple

quantum mechanical rules such as quantum

statistics, single scattering partial waves, and

quantum threshold laws provide the basis for

understanding of the molecular loss rates at

ultracold temperature [3]. Finally, we report

the observation of dipolar collisions in the

polar molecular gas [4].

[1] K.-K. Ni, S.Ospelkaus, M. H. G. de Miranda et al., /Science / 322, 231 - 235 (2008).

[2] S. Ospelkaus, K.-K. Ni, G. Quemener et al., Phys. Rev. Lett. 104, 030402 (2010).

[3] S. Ospelkaus, K.-K. Ni, D. Wang et al., Science 327, 853 (2010).

[4] K.-K. Ni, S. Ospelkaus, D. Wang et al., Nature *464*, 1324 (2010).

Left: split-ring resonator; The blue arrow represents the

incident THz electric field direction, green represents the

induced current inside the metal and red shows the THz

magnetic field lines. Right: time trace of the THz mag-

netic near field inside the element for two different in-

plane orientations of the sample.

12

O5 O6

Optical parametric oscillator based off-axis integrated cavity output spectro-scopy for real time breath monitoring

Denis D. Arslanov, Simona M. Cristescu,

Frans J. M. Harren

Molecular and Laser Physics,

Institute for Molecules and Materials,

Radboud University

A fiber-amplified, diode-laser pumped,

optical parametric oscillator (OPO) is

combined with Off-Axis Integrated Cavity

Output Spectroscopy (OA-ICOS). The

cw OPO (power 1.2 W, tuneability

3-4 µm, 5 cm-1 mode-hop free tuning)

has a tuning speed of 100 THz/s, which

is ideal for rapid and sensitive trace gas

detection. Combined with OA-ICOS a

detection limit of 50 pptv of Ethane

(C2H6) in Nitrogen was obtained in

0.25 second at 2997 cm-1, corresponding

to a Noise Equivalent Absorption

Sensitivity of 4.8 ×10-11 cm-1 Hz-1/2. The

system demonstrates real-time measure-

ments of ethane, methane, acetone and

water in exhaled human breath.

Peptide dissociation by keV ions andVUV photons

Sadia Bari1,Olmo Gonzalez-Magaña1,

Geert Reitsma1, Josephina Werner2,

Stefan Schippers2, Ronnie Hoekstra1,

Thomas Schlathölter11 KVI, Rijksuniversiteit Groningen2 Justus-Liebig-Universität Giessen

Gas phase peptide ion fragmentation is

the underlying process for peptide and

protein identification by means of tan-

dem mass spectrometry. This presenta-

tion will focus on the first studies of

keV ion-induced dissociation (KID) of

the peptide leucine-enkephalin [1]. In

contrast to low energy techniques,

amino-acid sidechains dominate the

fragment spectrum. Backbone scission is

a weak channel. The results can be

understood on basis of peptide excitation

due to electronic stopping. A pronounced

dependence of the fragmentation pattern

on the electronic structure of the projec-

tile ions can be attributed to different

electron capture efficiencies from locali-

zed molecular orbitals.

The KID results will be compared with

data for VUV photo-induced dissociation

which we took at the BESSY II synchro-

tron (Berlin). VUV interaction with sim-

ple peptides is also of fundamental astro-

biological interest because it could have

important implications for the develop-

ment of primitive life.

[1] Sadia Bari, Ronnie Hoekstra and

Thomas Schlathölter, Phys. Chem. Chem.

Phys.12, 3376 (2010), front cover article

13

O7 O8

Investigation of highly excited states of H3

+ through action spectroscopy: Is there order in chaos?

Annemieke Petrignani, Max Berg,

Dennis Bing, Florian Grussie, Andreas Wolf

Max-Planck Institute for Nuclear Physics,

Heidelberg, Germany

H3+ is the benchmark for polyatomic

molecules and initiator of the interstellar

chemical network leading to larger mole-

cules. Though it has been over 30 years

since its first laboratory observation [1],

H3+ still exhibits many unknown (reac-

tion) properties. At present, spectroscopic

observations cover only part of the H3+

spectrum [2, 3]. We have investigated

the highly excited region of H3+ using

high-sensitivity action spectroscopy in a

RF 22-pole ion trap. We have measured

transitions up to 16600 cm-1, reaching

states with over 5 vibrational quanta [4].

As a first, we have measured transition

intensities and derived the Einstein B

coefficients.

[1] T. Oka, Phys. Rev. Lett. 45, 1980, 531-534

[2] H. Kreckel, D. Bing, S. Reinhardt,

A. Petrignani, M. Berg, A. Wolf, J. Chem.

Phys. 129, 2008, 164312

[3] C.P. Morong, J.L. Gottfried, T. Oka, J. Mol.

Spectrosc. 255, 2009, 13-23

[4] M. Berg, D. Bing, F. Grussie, A. Petrignani,

A. Wolf, to be submitted

Entanglement-assisted atomic clock beyond the projection noise limit

Jelmer J. Renema1, A. Louchet-Chauvet1,

D. Oblak1, J. Appel1, P. J. Windpassinger1,

U. Hoff1, N. Kjærgaard1,E. S. Polzik1

1 Quantop, Niels Bohr Institute,

University of Copenhagen, Denmark

In a proof-of-principle experiment, we

show how the performance of an atomic

clock can be enhanced by spin squeezing.

Using a quantum non-demolition measu-

rement, we create entanglement in a

cloud of 105 cold Caesium atoms [1]. By

using a modified Ramsey clock sequence,

this entanglement is used to enhance the

sensitivity of an atomic clock. The experi-

ments show an improvement of 1.1 dB in

the clock's signal-to-noise ratio, as com-

pared the atomic projection noise limit

[2]. I will also talk about the develop-

ment of a newer version of this experi-

ment, which uses evanescent fields

around a nanofiber instead of a conven-

tional dipole trap for atom trapping.

[1] J. Appel et al. Proc. Natl. Acad. Sci. U.S.A. 27

(106) 10960, 2009

[2] A. Louchet-Chauvet et al. ArXiv:0912.3895,

2009

14

O9 O10

Plasmonic optical vortex tomography

Philip Chimento, Gert ’t Hooft, Eric Eliel

Leiden University

Topologically complex light fields, such

as speckle patterns, abound with optical

phase vortices. The common way of

determining a vortex-carrying beam’s

vortex charge involves interfering it with

a plane wave. The interference pattern

exhibits a dislocation starting from the

vortex, from which one determines the

vortex charge.

We present an elegant tomographic

method for analyzing the wavefronts of

optical vortices by means of surface plas-

mon polaritons. We use a subwavelength

slit in a gold film to cut slices from an

optical vortex beam, and measure the dif-

fraction of the generated plasmons by

scattering them off a second slit. By

moving the slits across the vortex beam,

we create a tomogram, from which we

can determine the beam’s vortex charge

at a glance. We present results for beams

of integer and half-integer vortex charge.

Efficient sorting of orbital angularmomentum states of light

Gregorius C. G. Berkhout1,

Martin P. J. Lavery2, Johannes Courtial2,

Marco W. Beijersbergen1, Miles J. Padgett2

1 Leiden University2 University of Glasgow

Measuring the orbital angular momen-

tum (OAM) state of a light beam is a

long-standing problem connected to the

use of OAM in the field of quantum

information and communication. Several

possible solutions to this problem exist,

but they are either very inefficient or too

complicated to include in a larger system.

Here, we present a novel method to effi-

ciently sort OAM states of light using two

static optical elements (see figure for the

phase profiles of these elements). The

optical elements perform a Cartesian to

log-polar coordinate transformation,

which converts the helical wave front

associated with an OAM state into a

beam with a transverse phase gradient.

A subsequent lens can then be used to

focus each input OAM state to a different

lateral position. We demonstrate the con-

cept experimentally by using two spatial

light modulators to create the optical ele-

ments, applying it to the separation of 11

OAM states.

Tomogram of a beam with vortex charge -3

15

Evening lecture I3

Opening up the black box called Physical Review Letters: AMO Physics in the leading physics journal

Deniz van Heijnsbergen

University of Amsterdam

How do you get a paper accepted in PRL?

What happens once you've submitted a

manuscript to Physical Review Letters

and how are referees chosen? What is

PHYSICS and what does it aim to

achieve? Why has PRL reinvigorated its

stringent criteria and what kind of impact

has it had so far?

These and other questions will be

discussed in a presentation about facts,

style, statistics, history, referees, authors

and ‘hot’ papers, which will hopefully

culminate in a lively debate about the

imminent changes in the landscape of

scientific publishing.

Femtosecond Coherent X-rayNanocrystallography at LCLS

Henry Chapman

Center for Free-Electron Laser Science, DESY,

Hamburg, Germany

The ultrafast pulses from X-ray free-electron

lasers have opened up a new form of pro-

tein nanocrystallography. The X-ray pulses

are of high enough intensity and of suffi-

ciently short duration that individual single-

shot diffraction patterns can be obtained

from a sample before significant damage

occurs. This “diffraction before destruction”

method may enable the determination of

structures of proteins that cannot be grown

into large enough crystals or are too radia-

tion sensitive for high-resolution crystallo-

graphy. Ultrafast pump-probe studies of

photoinduced dynamics can also be studied.

We have carried out experiments in cohe-

rent diffraction from protein nanocrystals,

including Photosystem I membrane protein,

at the Linac Coherent Light Source (LCLS)

at SLAC. The crystals are filtered to sizes

less than 2 micron, and are delivered to the

pulsed X-ray beam in a continuously flo-

wing liquid jet. Millions of diffraction pat-

terns were recorded at the LCLS repetition

rate of 30 Hz with pnCCD detectors, in a

instrument designed and built by the Max

Planck Advanced Study Group at CFEL.

Tens of thousands of the single-shot diffrac-

tion patterns have been indexed, and

combined into a single crystal diffraction

pattern, which can be phased for structure

determination and analysed for the effects

of pulse duration and fluence. Details of

these first LCLS experiments and analysis

will be discussed.

16

O11 O12

Separate gain media, an alternativeapproach to mode-locking

Ruud M. Oldenbeuving1, C.J. Lee1,

P.D. van Voorst2, H.L. Offerhaus1,

K.J. Boller1

1 University of Twente, The Netherlands2 Sensor Sense, The Netherlands

We present an alternative scheme to

laser mode-locking and discuss its un-

usual properties and feasibility using a

theoretical model. A large set of spatially

separated single-frequency continuous-

wave gain media (lasers) are mutually

phase-locked by nonlinear feedback from

a common saturable absorber. As a result,

ultra short pulses are generated. The

alternative scheme offers three significant

benefits: the light that is amplified in

each laser is continuous wave, thereby

avoiding issues related to group velocity

dispersion and nonlinear effects that can

perturb the pulse shape. The set of fre-

quencies on which the laser oscillates,

and therefore the pulse repetition rate, is

controlled by the geometry of resonator-

internal optical elements, not by the cavi-

ty length. Finally, the bandwidth of the

laser can be controlled by switching gain

modules on and off. This scheme offers a

route to mode-locked lasers with high

average output power, repetition rates

that can be scaled into the THz range,

and a bandwidth that can be dynamically

controlled.

Widely tunable XUV combs for highresolution Ramsey spectroscopy

Tjeerd J. Pinkert1, D.Z. Kandula1,2,

C. Gohle1,3, I. Barnes1, J. Morgenweg1,

W. Ubachs1, K.S.E. Eikema1

1 LaserLaB, Vrije Universiteit, Amsterdam

2 Present address: MBI, Berlin

3 Present address: LMU, Munich

We demonstrate the tunability of our

XUV frequency comb to wavelengths in

the range of 50 nm to 85 nm based on

the 15th, 13th and 9th harmonic of an

amplified IR frequency comb laser.

Several states in helium, neon and argon

were excited with the XUV comb, resul-

ting in high-contrast Ramsey-type signals

(see the figure for an example of argon

signal). Previously, comb spectroscopy on

helium has been demonstrated in our

group with an unprecedented accuracy of

6 MHz at 51.5 nm, challenging state of

the art QED calculations. The results

indicate that a similar accuracy over the

whole wavelength range from 85 nm

down to 50 nm is now possible.

17

O13 O14

IR spectroscopy of ionized corannulene

Hector Alvaro Galue1, Corey Rice2,

John P. Maier2, Jeffrey Steill1, Jos Oomens1,3

1 FELIX facility, FOM Rijnhuizen2 University of Basel, Switzerland3 HIMS, University of Amsterdam

Corannulene (C20H10) is a bowl-shaped

highly symmetric molecule (C5v) belon-

ging to the family of polycyclic aromatic

hydrocarbons composed of five perifused

aromatic rings around a central five-mem-

bered ring. Its relevance includes potential

applications as a functional nanomaterial.

Additionally, the occurrence of corannule-

ne in interstellar environments has been

suggested and possibly plays a role in the

formation of interstellar C60. Here, I

present the first gas-phase infrared spectra

of radical cation and protonated corannu-

lene recorded by infrared multiple-photon

dissociation spectroscopy using FELIX. The

measured spectra of both forms are com-

pared to theoretical spectra obtained from

quantum-chemistry calculations carried

out at various levels of theory. In case of

the protonated form, the good agreement

of theoretical and experimental spectra

indicates that protonation occurs on one

of the peripheral C-atoms, forming a sp3

hybridized carbon. For the radical cation,

the measured spectrum was analyzed

taking into account geometry distortions

induced by the Jahn-Teller vibronic effect

as a consequence of the degenerate 2E1

state. Accordingly, this effect correlates

with a pronounced charge redistribution,

particularly, around the five-membered

inner ring, influencing the IR intensities

of the CH bending vibrations in the

1000-1250 cm-1 region.

FLARE: a new THz Free Electron Laser atthe Radboud University Nijmegen

Vitali Zhaunerchyk, Rienk J. Jongma,

Wim J. van der Zande

Radboud University Nijmegen

The TeraHertz (THz) frequency range is

highly relevant for biomolecular physics

and solid state physics in high magnetic

fields. Unfortunately, this region of the

spectrum still lacks both versatile and

powerful sources. Since, in contrast to

“traditional” lasers, the frequency of the

light generated by a Free Electron Laser

(FEL) is not limited by internal properties

of an active medium but can be selected

by proper choices of undulator and elec-

tron energy, FEL technology is well suited

for the generation of THz radiation.

FLARE (Free electron Laser for Advanced

spectroscopy and high-Resolution

Experiments), which is designed to gene-

rate THz light at wavelengths of 0.1 mm

(3 THz) - 1.5 mm (0.2 THz), has been

funded at the Radboud University

Nijmegen, and is scheduled to be in ope-

ration in the middle of 2011. Since the

electron bunches employed by FLARE are

comparable in size to the length of the

THz light, short-pulse effects will play an

essential role in the FLARE operation.

18

I4 O15

Quantum control of single spins and single photons in diamond

Ronald Hanson

Kavli Institute of Nanoscience,

Delft University of Technology

Quantum control of light and matter

is an outstanding challenge in modern

science. Diamond-based materials have

recently emerged as a unique platform

for quantum science and engineering [1].

Spins of single Nitrogen-Vacancy (N-V)

color centers in diamond can be imaged,

initialized and read out optically, and

show quantum coherence even at room

temperature. Full control over the spin

state and the optical transition may ena-

ble exciting applications such as long-

distance quantum teleportation and

quantum information processing.

Moreover, the tunable interactions of

the NV center with its environment also

make this system an excellent test bed

for fundamental studies on decoherence,

spin-bath interactions, and light-matter

interactions in engineered nanostruc-

tures.

In this talk we will present our latest

results on quantum control of the optical

transition of single NV centers [2], as

well as on advanced decoupling schemes

to protect single-spin coherence [3].

[1] D.D. Awschalom, R.J. Epstein and R. Hanson,

Scientific American 297, 84 (2007).

[2] L Robledo et al., http://arxiv.org/abs/

1005.4428.

[3] G. de Lange et al., Science (in press).

Towards quantum information proces-sing with quantum dots in polarization-degenerate oxide-apertured micropillars

Cristian Bonato1, Jan Gudat1,

Susanna Thon2, Hyochul Kim2,

Martin van Exter1, Dirk Bouwmeester1,2

1 Huygens Laboratory, Leiden University (NL)2 University of California Santa Barbara (USA)

Hybrid photon-matter systems hold great

promises for quantum information pro-

cessing since they allow exploiting diffe-

rent quantum systems at the best of their

potentials. For example, photons are ideal

candidates for long distance communica-

tion, while matter qubits are more suited

for local storage and processing.

We describe a technique to create entan-

glement between the polarization state

of a single photon and the spin of an

electron trapped in a self-assembled

InAs/GaAs quantum dots, via cavity-QED

in the weak coupling regime and the

optical selection rules for the dot trion

statet. In particular, micropillar cavities

with oxide apertures provide an excellent

system to implement such schemes, since

they exhibit strong Purcell factors and

they support high-quality optical

Gaussian modes. We discuss how the

fundamental optical mode for such cavi-

ties can be tuned to polarization degene-

racy (a prerequisite to create coherent

superpositions) and how the dot optical

transitions can be fine-tuned applying a

controlled strain via laser-induced surface

defects.

19

O16 O17

Electromagnetically induced transparency in a semiconductor

Alok U. Chaubal1, Maksym Sladkov1,

Alexander R. Onur1, Morten P. Bakker1,

Dirk Reuter2, Andreas D. Wieck2,

Caspar H. van der Wal1

1 University of Groningen2 Ruhr-Universität Bochum

We report the observation of Electro-

magnetically Induced Transparency (EIT)

in GaAs. EIT is the phenomenon that an

absorbing optical transition becomes

transparent because destructive quantum

interference with another driven transi-

tion prohibits populating the optically ex-

cited state. This yields strong field-matter

interactions, and EIT lies at the heart of

various quantum information schemes.

EIT can occur with three-level systems as

in Fig. a), with two low-energy spin states

that have a long coherence time. We used

an ensemble of donor-bound electrons in

GaAs, which can be operated as hydrogen-

like atoms. Our implementation in a

semiconductor gives access to very com-

pact quantum optical devices with high

optical density, and a new approach to

controlling and probing spin coherence in

a semiconductor.

Transport of 3D spatially entangled photons through a hollow-core photoniccrystal fibre

Wolfgang Löffler1, E. R. Eliel1, T. G. Euser2,

M. Scharrer2, P. St.J. Russell2,

J. P. Woerdman1

1 LION, Universiteit Leiden2 Max Planck Institute, Erlangen

Spatially entangled photons give access to

a high-dimensional Hilbert space, this is

promising for quantum information and

communication. Compared to the well-

known polarisation-based 2D qubit case,

d-dimensional spatially entangled photon

qudits show stronger quantum correla-

tions. Fibre transport of such spatial

qudits is considered impracticable:

Photon fields with spatial structure are

by definition multi mode; therefore,

multi-mode fibres have to be used and

these suffer usually from strong mode

mixing. This quickly destroys the quan-

tum correlations. We demonstrate here

for the first time successful fibre trans-

port of 3D spatially entangled photons

(qutrits) using a hollow-core photonic

crystal fibre. We show 3D photon

entanglement after fibre passage and

discuss the limits of multi-mode

entanglement transport in optical fibres.

20

O18 O19

DNA scaffolds for quantum optics

Sumant S.R. Oemrawsingh1, R. Leijssen1,

P. O'Neill2, E.R. Eliel1, D. Fygenson2,

E.G. Gwinn1, D. Bouwmeester1,2

1 Huygens Laboratory, Leiden University

2 University of California, Santa Barbara

Optical labeling of DNA is a well-develo-

ped technology, that makes use of site-

specific bonding techniques to attach

emitters such as fluorescent dye molecu-

les or quantum dots to the DNA. A more

recent development is the discovery that

silver nanoclusters self-assemble onto

single-stranded DNA. These clusters are

so small (~15 atoms) that they behave

as molecules and thus display discrete

energy levels. Contrary to the more

conventional optical labels, the size of

the cluster and its absorption and emis-

sion bands are strongly influenced by the

base sequence of the host DNA, allowing

us to directly assemble a specific emitter.

The additional possibility of attaching

such DNA-encapsulated silver nanoclus-

ters to DNA scaffolds allows for the crea-

tion of elaborate 2D and 3D structures

with closely-spaced fluorescent silver

clusters attached at chosen positions with

nanometer accuracy. These scaffolds

carry great promise as scalable quantum-

emitter arrays with applications for

nanoscale quantum optics experiments.

The subsonic beam based atom laser

Johnny M. Vogels, L. Kindt, K. van Aken,

P. Bons, P. van der Straten

University of Utrecht

We convert a beam of supersonic atoms

to a subsonic beam with densities high

enough for evaporative cooling to dege-

neracy. The supersonic beam is slowed

down using a shock wave. After the

shock wave, the beam is further slowed

down using gravitational forces in thesame direction as the flow. The beam also

unintentionally cooled against the guide

wires, which compresses the beam even

more. We end up with a beam which has

up to 20 times the collision rate, is at

comparable temperature as the original

beam, and is at least 20 times as slow.

We evaporatively cool the beam in

packets to Bose Einstein condensation,

which are then released as atom laser

pulses further into the guide.

21

O20 O21

Spectroscopy of a forbidden transitionin a Bose-Einstein condensate of 4Heand a degenerate Fermi gas of 3He

Rob van Rooij1, J. Simonet1,2,

M.D. Hoogerland1,3, R.R. Rozendaal1,

J.S. Borbely1, K.S.E. Eikema1, W. Vassen1

1 LaserLaB Vrije Universiteit, Amsterdam2 ENS, Paris3 University of Auckland

We present the first observation as well

as a frequency measurement of the mag-

netic-dipole transition between the triplet

and singlet metastable states of helium.

The exact transition frequency forms a

good test for modern QED theory. To

observe the transition (8 Hz natural line-

width), we load a Bose-Einstein conden-

sate of triplet metastable 4He atoms into

a 1557-nm optical dipole trap, and subse-

quently illuminate the atoms 2-8 seconds

with a tunable spectroscopy beam from

the same laser. If the spectroscopy beam

excites the singlet metastable state, which

is anti-trapped, we observe a strong trap

loss. All frequency measurements (refe-

renced to a fiber comb laser) are correc-

ted with precision determinations of the

AC-Stark shift, Zeeman shift and recoil

shift allowing ~10 kHz accuracy. We have

also performed a similar measurement in

metastable 3He, which, due the Pauli

principle, shows additional shifts due to

population of many states in the optical

trap potential.

Feshbach resonances in Fermi mixturesof ultracold 40K

Antje Ludewig1, T.G. Tiecke2,

F.M. Spiegelhalder1, J.T.M. Walraven1

1 Van der Waals-Zeeman Instiuut,

Universiteit van Amsterdam2 Harvard University, Cambridge

We report on the measurement of

Feshbach resonances in ultracold Fermi-

Fermi mixtures of 40K in an optical

dipole trap (ODT). In the same trap we

have realized degenerate spin mixtures of

106 40K atoms at T=0.3(1)TF. The cold

atoms are loaded from a two dimensional

magneto optical trap (MOT). After eva-

poration in an optically plugged magnetic

trap the 40K atoms are loaded into

optical tweezers and transported over a

distance of 21.5cm into a science cell.

Using microwave radiation and resonant

light we prepare non degenerate mixtures

of 2 * 105 40K atoms in various Zeeman

states. 40K has a rich hyperfine structure

(F=9/2) and many Feshbach resonances

involving the different states are expec-

ted. We measure these resonances using

magnetic field coils designed for high

homogeneity. We report on our progress

exploring Feshbach resonances in 40K

and locating resonances favourable for

the investigation of many body states.

22

I5

Universal Efimov physics in ultracold gases

Servaas Kokkelmans

Eindhoven University of Technology

A remarkable prediction of three-body

theory with resonantly enhanced two-

body interactions is the existence of a

universal set of weakly bound triatomic

states known as Efimov trimers. We

observed the existence of a universal

regime for these trimers through three-

body recombination loss in the vicinity

of a Feshbach resonance [1], for ultra-

cold Li-7 atoms.

The reported results crucially depend on a

careful mapping of the scattering length

on the magnetic field. We characterize

two broad Feshbach resonances in diffe-

rent spin states by fitting the binding

energies of weakly bound molecules,

created by radio-frequency association,

by making use of a theoretical coupled

channels analysis. This gives rise to a very

precise determination of the absolute

positions of the Feshbach resonances,

and to very precise values of the singlet

and triplet scattering length that charac-

terize the molecular potentials of lithium.

[1] N. Gross, Z. Shotan, S. Kokkelmans and

L. Khaykovich, Phys. Rev. Lett. 103, 163202

(2009), and arXiv:1003.4891.

23

P1 P2

Far-IR action spectroscopy of strongly bound systems

J.M. Bakker, V.J.F. Lapoutre,

A.F.G van der Meer, B. Redlich, J. Oomens

FOM Rijnhuizen

The resonant absorption of multiple

infrared (IR) photons by gas phase mole-

cules and ions can lead to either frag-

mentation or ionization of the species.

Using this ionization or fragmentation

as a probe, action spectroscopy is a well-

established technique for measuring

the IR spectra of (bio)molecules/ions,

clusters and complexes in the gas phase.

At lower wavenumbers, the efficient exci-

tation leading to the ‘action’ is hindered

by a combination of the lower energy

carried per photon and the typically

lower IR absorption cross-sections.

We demonstrate that, using the high

IR fluence available in FELICE, the

Free-Electron Laser for IntraCavity

Experiments, IR action spectroscopy is

feasible down to at least 200 cm-1 for

strongly bound systems. Results will be

presented for metal clusters and for

PAH cations.

Ultracompact and ultrafast optical switching based on slow light

Daryl M. Beggs1, Tobias Kampfrath1,

Thomas F. Krauss2, L. (Kobus) Kuipers1

1 FOM Institute AMOLF2 University of St Andrews

Slow-light dramatically increases the

interaction between light and matter, and

it can be generated on a silicon chip

using the dispersion properties of photo-

nic crystal waveguides. This on-chip

slow-light will allow for the creation of

smaller, faster and more energy efficient

optical components.

Here we demonstrate a silicon optical

switch based on two coupled photonic

crystal waveguides. It can reroute optical

signals from one to the other within 3ps

of the absorption of an ultrafast (100fs)

pump-pulse generating free carriers in

the silicon, shifting its refractive index

and actuating the switch.

The slow-light allows for the enhance-

ment of the phase-shift between the odd

and even supermodes of the coupled

waveguides, yielding a switching length

of just 5µm (~3λ).

1. T. Kampfrath et al., Applied Physics Letters

94 241119 (2009)

2. D. M. Beggs et al., Optics Letters 33 (2) 147-

149 (2008)

24

P3 P4

ZFEL: A compact, soft X-ray FEL in The Netherlands

J.P.M. Beijers, R. Hoekstra for the

ZFEL team

KVI, University of Groningen

We outline our plans to construct a soft

X-ray FEL facility at KVI, University of

Groningen. This new facility will be

based on a 2.1 GeV normal-conducting

electron linac followed by an undulator

and will produce X-ray laser light with

wavelengths down to 0.8 nm, pulse

lengths of (tens of) fs and a maximum

repetition rate of 1 kHz. The electron

linac will be driven by an RF photo-

injector and X-band acceleration struc-

tures with an acceleration gradient of

100 MV/m. Seeding techniques will be

implemented to also establish longitu-

dinal coherence. The high acceleration

gradient makes it possible to construct a

very compact facility in a cost-effective

way, e.g. the entire length of the FEL will

be on the order of 100 meters. The new

facility is meant as an international

user facility with a strong contribution

of local AMO, material science and

biochemistry groups. The design and

construction will be a collaborative

effort with contributions from different

(inter)national research groups.

Rydberg Atom Lattices

R.van Bijnen

Eindhoven University of Technology

Ultracold atomic gases are used extensi-

vely to realize textbook examples of

condensed matter phenomena. Typically,

such experiments deal with neutral

atoms interacting via short-range VdW

potentials much weaker than the

Coulomb interactions between electrons

in solids.

In contrast, we study highly excited

Rydberg atoms arranged on a self-assem-

bled lattice, representing a more accurate

dilute model system for e.g. metallic

conductors. Here, the interaction

strengths approach Coulombic potentials,

while retaining the controllability charac-

teristical of cold atom experiments.

Rydberg lattices can also cross over to the

plasma regime with a quantumdegenerate

electron gas by increasing the Rydberg

excitation, making such systems a

scientific playground for studying various

fundamental phenomena.

We plan an experimental and theoretical

investigation of such self-assembled

Rydberg lattices, following a recent

proposal by T. Pohl et al. [1]. Using a

tailored excitation scheme, the correlated

crystal state is built up from a disordered

atomic gas. We give a theoretical treat-

ment of this scheme and the Rydberg

crystal ground states, and discuss its

feasibility.

[1] PRL 104 043002 (2010)

25

P5 P6

Electron transfer in collisions of keV ionswith ultracold atoms

Ina Blank1, Corine Meinema1,

Ronnie Hoekstra1, Simone Götz2,

Bastian Höltkemeier2, Thomas Amthor2,

Matthias Weidemüller2

1 KVI, Atomic Physics, University of Groningen2 Physikalisches Institut, University of

Heidelberg

Transfer of two electrons in collisions of

ions with atoms is an example of correla-

ted many-particle dynamics of a

Coulomb system. The electron transfer is

studied by precisely measuring the

momentum of the recoils ions. The target

is provided by a magneto-optical trap

which ensures that the recoil momentum

is not limited by the initial thermal

velocity spread.

We have investigated double electron

transfer in collisions of O6+ with Na(3s).

Two different reaction channels are

observed, namely population of final

states O4+(3l3l’) and O4+(3ln’l’) with

n’≥6. From the scattering angle of the

projectile and comparison with potential

energy curves of the system it is deduced

that the two final states are populated via

different mechanisms: Final states

O4+(3ln’l’) are populated by sequential

electron transfer, while the two electrons

populating the O4+(3l3l’) final states are

transferred simultaneously. Collision

energy dependent measurements reveal

an increase of the simultaneous electron

transfer with decreasing energy.

Cold molecular collisions with merged beams

Janneke Blokland, Henrik Haak,

Gerard Meijer, Sebastiaan van de Meerakker

Fritz-Haber-Institut der Max-Planck-

Gesellschaft, Berlin

Beams of Stark decelerated molecules

have proven to be versatile in studying

collisions between atoms and molecules

at low collision energies [1,2]. In these

crossed-beam experiments the minimal

collision energy was limited to 50 cm-1

by the center-of-mass kinetic energy of

the atoms (50 cm-1), hampering the

observation of resonances in the scatte-

ring cross-section that are predicted to

occur at even lower energies.

Currently we are developing a setup to

collide merged beams of atoms and

Stark-decelerated molecules to reach

collision energies down to 5 cm-1.

We will use a curved hexapole to guide

Stark-decelerated metastable CO molecu-

les, letting them merge with a beam of

He atoms. He-CO* complexes have a

shallow potential which only supports a

limited number of bound states [3].

Therefore the resonances are expected to

be well-separated for these complexes,

facilitating their observation.

[1] Gillijamse et al. Science 313, 1617 (2006)

[2] Kirste et al. arXiv:1006.0937v1 (2010)

[3] Zeimen et al. Journal of Chemical Physics

119, 131 (2003)

26

P7 P8

Characterization of compression andslowdown of a supersonic beam with ashock wave and evaporative cooling

P. Bons, L. Kindt, K van Aken,

P. van der Straten, J.M. Vogels

University of Utrecht

We show the propagation of a shock

wave in a beam of supersonic cold guided

atoms. By observing the absorption of the

beam as a function of position and detu-

ning and, we detect a sudden increase in

the beam temperature when the shock

wave passes by. Simultaneously, the

density increases. After the shock wave,

we observe that the density keeps increa-

sing and the temperature keeps decreases.

We attribute this to evaporative cooling

of atoms against the guide wires.

Unexpectedly, this happens even after

the shock wave is reckoned to have

reached the entrance of the guide. At

this point the shock wave was expected

to destabilize.

Absence of strong dynamical nuclearpolarization from optical driving ofdonor-bound electron spins in GaAs

Alok U. Chaubal1, Morten P. Bakker1,

Maksym Sladkov1, Alexander R. Onur1,

Dirk Reuter2, Andreas D. Wieck2,

Caspar H. van der Wal1

1 University of Groningen 2 Ruhr-Universität Bochum

Spins of donor-bound electrons in GaAs

have hyperfine interaction with ~105

nuclear spins, and their fluctuations

limit the electron spin coherence. If the

electron spin is driven out of equilibrium,

dynamical nuclear polarization (DNP)

can occur. We studied how DNP occurs

during optical pumping and quantum-

optical experiments with these electrons,

and find the effects much weaker than in

various related experiments.

A narrow transmission peak (from a two-photon

quantum interference) within an absorption line

of donor-bound electron shows a shift (larger

Zeeman energy) and narrowing (improved spin

coherence) after DNP by optical pumping. The

effect relaxes in time from 0 min to 50 min after

the optical pumping.

27

P9 P10

Time-resolved imaging studies of photofragmentation dynamics in cold isolated molecules

Congsen Meng, Daniel Irimia,

Maurice H.M. Janssen

Laser Centre and Department of Chemistry,

Vrije Universiteit Amsterdam

Ultra-fast dynamics in electronically

excited small molecules is studied by

femtosecond velocity map ion/electron

imaging and time-of-flight mass spectro-

metry. The experiments are performed

using a two-colour pump-probe configu-

ration with laser pulses centred at

400 nm and 266 nm. The supersonic

molecular pulses are generated by a novel

cantilever piezo valve capable to produce

cold beams with translational temperatu-

res down to 300 mK and a FWHM pulse

width as short as 7 µs. The valve can

operate at various repetition rates

between DC and 5 kHz with a moderate

backing pressure of 6 Bar and a nozzle

diameter of 200 µm. The main advan-

tages conferred by the piezo-valve relies

on its compactness, short and variable

molecular pulse widths and low genera-

ted gas load making it suitable for

experimental machines characterized by

low pumping speeds.

Damage to plasmid DNA thin films induced by low energy ions

H.M. Dang, M.J. van Goethem,

S. Brandenburg, R. Hoekstra, T. Schlathölter

KVI Atomic and Molecular Physics,

University of Groningen

The effect of ionizing radiations upon

biological material continues to evoke

great scientific interest. The cytotoxic

effects of high energy radiation, applied

for instance in radiation cancer therapy,

can ultimately be linked either to direct

ionization of DNA or to production of

reactive radical species which subsequent-

ly damage DNA.

We have investigated keV H+ and Cq+

induced damage to plasmid DNA thin

films as a function of ion energy and

dose. The films were produced by evapo-

ration from aqueous solution on an

aluminum substrate.

To correctly determine the dose deposited

into the plasmids by different keV ions

and at different kinetic energies, trajecto-

ry calculations delivering penetration

depth and beam straggling are required.

With these results and our experimental

data, we can determine the dose depen-

dence of single and double strand break

induction in plasmids for the various

systems under study. The results will be

discussed in the framework of molecular

mechanisms underlying biological

radiation damage.

28

P11 P12

Ultrafast preparation and detection ofarbitrary coherent dark states withdonor-bound electrons in GaAs

Sergii Z. Denega1, Maksym Sladkov1,

Dirk Reuter2, Andreas D. Wieck2,

Caspar H. van der Wal1

1 University of Groningen2 Ruhr-Universität Bochum

We report an optical pump-probe study

of spin coherence of donor-bound elec-

trons in GaAs. We find that single pump

pulses prepare the spins in a coherent

dark state via an ultrafast stimulated

Raman process. Two orthogonal polariza-

tion components in the pump pulses

each address one leg of the Raman sys-

tem. The phase and amplitude difference

between these components govern which

spin state is prepared, and we can prepare

any superposition of spin states. This

preparation occurs 1000 times faster

than the system's spontaneous emission

and decoherence time, and probably

relies on rapid pulse-induced decoherence

that is unique for solid-state systems.

High resolution spectroscopy of

hydrogen and its isotopomers using

VUV synchrotron radiation and a Fourier-transform spectrometer

G. D. Dickenson1, T. Ivanov1, N. de Oliveira2,

D. Joyeux3, W.Ü.L. Tchang-Brillet3,

M. Glass-Maujean4, L. Nahon2,

M. Roudjane2, W. Ubachs1

1 Vrije Universiteit, Amsterdam2 Synchrotron Soleil, Paris3 Observatoire de Paris-Meudon, France4 Université Pierre et Marie Curie

The D1Πu system of H2 undergoes

predissociation via the interaction with

a single continuum. It is the model for

the understanding of this phenomenon.

We have re-investigated this state at the

highest accuracy to date extending the

measurements to the final vibrational

level of the system.

The Lyman and Werner bands of H2 can

be used as a probe for variation in funda-

mental constants. Recently HD has been

suggested as a second system for such a

test. In light of this we have re-investiga-

ted the Lyman and Werner bands of HD

to an accuracy suitable for comparison

with quasar data.

The measurements were taken at the

Synchrotron Soleil where a novel Fourier

transform spectrometer has been develo-

ped. It is the first instrument of its kind,

operating in the vacuum ultraviolet

(VUV) to wavelengths of 60 nm without

the use of a beam splitter.

The phase of spin precession depends on the

polarization of the pump pulse (4.2 Kelvin, 7 Tesla).

29

P13 P14

Cold molecules by photodissociation ofspatially oriented molecules

Dimitar Dobrikov, Maurice H.M. Janssen

LaserLAB Amsterdam and Department of

Chemistry, VU University Amsterdam

We present a novel method to produce

translationally cold molecules by photo-

dissociation of laboratory oriented mole-

cules. When a bond in a molecule is

impulsively broken by the absorption of a

single photon, the momentum imparted

on the fragments in the center-of-mass

can easily be equal to the laboratory velo-

city of the dissociated parent molecule. If

we direct the recoil to be opposite to the

molecular beam velocity a molecular

fragment with vanishing velocity is for-

med.

A translationally cold pulsed beam of

quantum state-selected and oriented

molecules of OCS is produced with a

novel homebuilt piezo valve [1]. The first

experiments have generated CO frag-

ments standing still in the laboratory

with a temperature of about T~80 mK. In

combination with a high-repetition rate

photolysis laser this novel method is able

to produce cold molecules at high repeti-

tion rate (1 kHz).

[1] D. Irimia, R. Kortekaas and M.H.M. Janssen,

Phys. Chem. Chem. Phys. 11, 3958 (2009);

Rev. Sci. Instruments 80 (2009), 113303

Source Temperature Measurements ofan Ultracold Electron Source

W.J. Engelen, M.A. van der Heijden,

E.P. Smakman, N. Debernardi,

E.J.D. Vredenbregt, O.J. Luiten.

Department of Applied Physics,

Eindhoven University of Technology

We report on the development of ultra-

cold electron beams, which are created

from a cloud of laser-cooled atoms by

near-threshold photoionization or field

ionization of Rydberg atoms.

The electron beams that are created from

this source will be used to perform sin-

gle-shot, ultrafast electron diffraction

(UED) experiments on crystals of macro-

molecules, such as proteins. This opens

the possibility to study the dynamics of

non-equilibrium structures with both

spatial and temporal resolution at the

atomic level (i.e. 1 nm and 100 fs).

To ensure high quality diffraction data,

the electron beams should be sufficiently

coherent, with a transverse coherence

length of at least a few lattice spacings of

the crystal under investigation. For pro-

tein crystals the lattice spacing is typically

a few nm.

We will present measurements of the

source temperature, which can be as low

as 10 K. Because of this very low tempe-

rature, the coherence length requirement

is amply fulfilled.

30

P15 P16

Coincidence Imaging and Femtosecond Pulse Shaping in Molecular Dynamics studies

Mohammad Fanood, Carl Stefan Lehmann,

Arno Vredenborg, Wim G. Roeterdink,

Maurice Janssen

LaserLAB Amsterdam and Department of

Chemistry, Vrije Universiteit Amsterdam,

We report on femtosecond time-resolved

experiments using a photo-electron &

photo-ion coincidence imaging machine

constructed at the laser centre in

Amsterdam to measure the full

three-dimensional momentum distribu-

tion of correlated electrons and ions.

Coincidence imaging is a technique in

which both the ejected photo-electron

and the ionic photofragment are measu-

red, in coincidence, with two time- and

position sensitive particle detectors.

From the data the complete energetic

and angular resolved distributions are

obtained.

In laser excitation of molecules with

femtosecond pulses different multi-

photon processes are easily induced

leading to various ionic atomic and

molecular fragment channels.

Apart from time-resolved coincidence

imaging we apply the femtosecond pulse

shaping technique to obtain detailed

information about mechanism under-

lying the coherent control. In this contri-

bution the instrumentations and their

characteristics of our experimental setup

will be presented.

A nanophotonic probe for random cavities

E.H. Frater, S.R. Huisman, J.P. Korterik,

J.L. Herek, A.P. Mosk, H.L. Offerhaus,

W.L. Vos, P.W.H. Pinkse

MESA+ Institute for Nanotechnology,

University of Twente

In a photonic waveguide, light can be

trapped in Anderson-localized modes [1].

We want to study these modes and their

interactions with embedded quantum

dots by mapping them out with a near-

field scanning optical microscope

(NSOM). Since the radiative properties

of the quantum dots require low tempe-

ratures, we will perform cryogenic experi-

ments.

We have started to set up a NSOM to do

initial experiments with photonic wave-

guides at room temperature and started

investigations for making a cryogenic

NSOM. We will report on the progress of

this project.

[1] L. Sapienza et al., Science 327, 1352 (2010).

Artistic view of a NSOM probing a localized mode

in a photonic waveguide with a small degree of

randomness (not visible).

31

P17 P18

Dissociation of free protonated peptidesby VUV-photons

O. Gonzalez-Mangana1, G. Reitsma1,

S. Bari1, J. Werner2, S. Schippers2,

R. Hoekstra1, T. Schlathölter1

1 KVI Atomic and Molecular Physics, RUG2 Justus-Liebig-Universität Giessen

The transport of biomolecules from space

to early earth could have important con-

sequences for the development of early

live. Therefore, the stability of peptides by

VUV-photon interaction is of fundamen-

tal interest. In order to study these inter-

actions, protonated peptides are produced

by an electrospray ionization source and

trapped in a three dimensional quadru-

pole in which they are interfaced with

synchrotron radiation in the 8-40 eV

range. The obtained spectra show diffe-

rent regimes of dissociation processes.

Below ionization potential the photon

energy is mainly absorbed by the peptide

bond, which leads to slow IVR governed

processes. Above ionization threshold

both fast dissociation through repulsive

states and slow IVR dissociation processes

can occur. The strongest observed peak is

related to the fast loss of the tyrosine

sidechain. Internal energy estimations

show that the fast tyrosine sidechain loss

efficiently cools the remaining peptide. It

is conceivable that such cooling processes

facilitate the survival of peptide substruc-

tures after photon absorption in space.

Global optimization of proton-protondecoupling sequences using self-learning algorithms

L.A.G. Grimminck, A. Brinkmann,

W.L. Meerts, A.P.M. Kentgens,

Radboud University

Proton-proton couplings are a major

cause of linebroadening in (bio-) Solid

State NMR.

Due to the typically strong nature of

these dipole-dipole couplings it is not

possible to average them to zero by

mechanical spinning. Combined Rotation

And Multiple Pulse Sequence (CRAMPS)

experiments are therefore currently the

best option.

Contemporary NMR spectrometers allow

the shaping of complicated pulses in both

amplitude and phase. All these possible

pulse shapes form a large space with

potentially good decoupling sequences. In

our approach we use evolutionary algo-

rithms, that are interfaced with a spec-

trometer, to explore and find the most

optimal solution in this vast space. This

approach also provides an insight in the

importance of experimental imperfecti-

ons, e.g. in pulses or cables. We will pre-

sent a comparison of the results with

those obtained via simulation.

32

P19 P20

3D tumor imaging by self interferencefluorescence endoscopy

Matthijs de Groot, Johannes F. de Boer

Vrije Universiteit Amsterdam

Early cancer diagnosis can be greatly

improved by employing recently develo-

ped fluorescent labels that selectively tar-

get tumors. However, effective endoscopic

imaging tools are needed to optimally

exploit the potential of these markers.

We will demonstrate a novel 3D fluores-

cence imaging technique ideally suited to

be incorporated in small endoscopes. The

technique, illustrated in the figure, is

based on the principle of self-interferen-

ce: by presenting the fluorescent photons

with two alternative optical paths they

are forced to interfere with themselves.

Alternating constructive and destructive

interference modulates the detected fluo-

rescence spectrum. The phase of this

spectral modulation uniquely identifies

the depth location of the fluorescent

source without the need for a mechanical

depth scanning mechanism. We demon-

strate in proof of principle experiments

that sub 10 µm sensitivity can be obtai-

ned with a depth of field of 1 mm.

Laboratory study of Rayleigh-Brillouinscattering for measuring the winds ofthe Earth

Z. Gu, W. Ubachs, M.O. Vieitez,

E.J. Duijn

Laser Centre Vrije Universiteit Amsterdam

An experimental and theoretical study

is carried out to determine the Rayleigh-

Brillouin line shape in different gases

for a range of pressures between 0.3 and

3 atmosphere. Spontaneous Rayleigh-

Brillouin scattering is measured in the

ultraviolet wavelength at 90 degrees of

scattering angle. The obtained line shapes

are compared with a description by the

TENTI-6 and TENTI-7 models. These

models had only been tested for a very

small subspace of gases, pressures and

mixtures. Hence the goal of the present

project is: measuring the spontaneous RB

scattering profile and comparing them to

both versions of the TENTI-models. This

project is intimately connected to future

missions of the European Space Agency.

33

P21 P22

Femtosecond imaging and coherentquantum control of molecular photodynamics

Daniel Irimia, Maurice H.M. Janssen

Laser Centre and Department of Chemistry,

Vrije Universiteit Amsterdam

Time-resolved photoion and photoelec-

tron velocity map imaging technique has

been used for the study of NO2 photo-

dynamics in a pump-probe excitation

scheme at 266 nm and 400 nm. The

pump-probe transients of both NO+ ions

and its corresponding photoelectrons

reveal the presence of oscillatory patterns

of various periods. A spatially masked

imaging detection method is used to dis-

tinguish among the different photoelec-

tron channels. Distinct oscillatory pat-

terns are observed in the transients up to

several ps for both the slow (near 0 eV)

and the fast (near 0.88 eV) photoelec-

trons. It was concluded that an oscilla-

ting and predissociating wavepacket in a

quasi bound potential of mixed character

may explain the oscillations observed in

the total photoelectron yield in the fast

channel near 0.88 eV.

The coherent quantum control of CF3I

and CH2BrCl photodynamics was studied

by frequency chirping of the femtosecond

laser pulses tunable within a frequency

window between 510-560 nm. The velo-

city map ion/electron imaging and the

TOF mass spectrometry show that dyna-

mics involves multiphoton absorption

mainly at five-photon level with small

contribution from additional sixth pho-

ton. It was observed that the fragmenta-

tion ratio can be strongly controlled by

modifying the chirp as well as the excita-

tion frequency.

Structural analysis of F0F1-ATPase activesite mimics by IR spectroscopy

Sander Jaeqx1, Jos Oomens1,2,

Anouk M. Rijs1

1 FOM institute for Plasma physics Rijnhuizen2 HIMS, University of Amsterdam

Biomolecular motors convert chemical

energy (ATP) into directed motion. In

F0F1-ATPase, a biomolecular motor, the

motion is initiated by conformational

changes at the active site. Little is known

on the conformational dynamics on the

molecular level because most experiments

to date are performed on the complete

protein, where the active site is hidden in

the protein environment. Here we will

study isolated model systems of the active

site. First we will focus on the distance

between glumatic acid (Glu) and argini-

ne (Arg) to mimic the active site of

F0F1-ATPase. In this project, REMPI and

IR-UV ion-dip spectroscopy are perfor-

med on Z-Glu-OH, Z-Arg-OH and

Z-Glu-(Ala)n-Arg-NHMe (n = 0, 1, 3) in

the gas phase, which enables us to deter-

mine intrinsic properties of the peptides.

Experiments using the Free-Electron Laser

for Infrared eXperiments (FELIX) combi-

ned with quantum chemical calculations,

reveal the optimal position of Glu and

Arg.

34

P23 P24

Structure and Magnetization ofTransition Metal Oxide Clusters

J. Jalink, C.N. van Dijk, Th. Rasing, A. Kirilyuk

Radboud University Nijmegen

Small transition metal clusters exhibit

novel electronic, magnetic and chemical

properties which scale non linearly with

the number of atoms within the cluster.

Pure transition metal clusters were stu-

died in the past and have shown a consi-

derable modification of the magnetic

ordering as compared to bulk. Moreover,

compound clusters, such as transition

metal oxides (TMO), can also exist in

compositions different from their bulk

stoichiometry.

However, to characterize the behavior

of such clusters, not only the magnetic

properties but also the geometrical

conformation and energy of the electrons

(DOS) within the cluster are of impor-

tance. Using multiphoton infrared vibra-

tional spectroscopy, done at FELIX, we

can unravel the conformation of the

cluster. For several structural isomers

the vibrational spectrum was calculated,

taking the magnetic order into account,

and compared to experimentally observed

transitions.

To confirm the calculated order, a

Stern-Gerlach deflection experiment is

performed. In such a way, unusual beha-

vior was already demonstrated for the

magnetic moments of several rare-earth

clusters; the experiments with (TMO)

clusters are being carried out.

A Molecular Fountain for High-Resolution Spectroscopy

Paul Jansen, Marina Quintero Pérez,

Wim Ubachs, Hendrick L. Bethlem

LaserLaB Vrije Universiteit Amsterdam

Since the end of 19th century, spectrosco-

py of atoms and molecules has improved

our knowledge of both physics and

chemistry. Today, high-resolution

spectroscopic measurements still serve

as stringent tests of various fundamental

theories and provide the tools to probe

new physics. We present our efforts to

create a molecular fountain for high-

resolution spectroscopy of ammonia

molecules. The molecules are Stark-

decelerated from 300 m/s to 5 m/s and

subsequently focused and cooled in the

radial direction using linear electrostatic

quadrupole lenses and in the vertical

direction using a cylindrical quadrupole.

Until now, we have been unable to see

any effects of the cylindrical quadrupole,

we discuss possible explanations and

solutions for this. In addition, we present

results of a detection scheme for ammo-

nia based on VUV-radiation.

35

P25 P26

Template-stripped buried grating forPlasmonics

J. Jose, F.B. Segerink, J.P. Korterik,

A. Gomez-Casado, J.L. Herek, H.L. Offerhaus

University of Twente

In this work, we combine a grating and a

prism to excite multiple Surface Plasmon

Polaritons (SPPs). Two types of gratings:

an exposed and a buried grating were

investigated in the near-field using a

near-field scanning optical microscope [1].

A template stripping technique was used

to fabricate the buried grating. A three-

dimensional view of the buried grating

placed on top of a glass prism exciting

multiple SPPs is shown in the Figure. The

half-width of the surface plasmon reso-

nances measured for the buried grating

are found to be smaller compared to the

exposed grating, which implies an increa-

sed propagation length for the SPPs.

[1] J. Jose, F. B. Segerink, J.P. Korterik, and

H.L. Offerhaus, Optics Express 16, 3 (2008).

Electron bunch-length measurementsusing Grating Enhanced PonderomotiveScattering

J.H.M. Kanters, A. Lassise, P.H.A. Mutsaers,

Department of Applied Physics,

Eindhoven University of Technology

The application of ultrafast electron bun-

ches allows for time-dependent electron

microscopy studies of processes at atomic

length and timescale. An example of such

a process is the melting of aluminum,

which is on picoseconds timescale [1]

and electron bunches with lengths down

to 100 fs are required. Ultrashort electron

bunches are usually generated by photo-

cathodes using femtosecond laser pulses,

but in our group a technique is developed

where RF technology is used to chop a

DC electron beam into sub-ps pulses.

However, precise knowledge of the bunch

length is needed to verify this technique.

In 2005 it was shown that an all optical

method utilizing electron-laser pulse

cross correlation can be used accurately

for electron bunch-length measurements.

This optical method, using the pondero-

motive force of two femtosecond laser

pulses forming a standing wave, will be

integrated in the aforementioned setup

and its implementation is the scope of

this research.

[1] B.J. Siwick, J.R. Dwyer, R.E. Jordan,

R.J.D. Miller, Science 302 (5649) 2003,

p. 1382

36

P27 P28

Molecular hydrogen ions, the proton-electron mass ratio and the proton size

J.C.J. Koelemeij, D.W. Noom, D. de Jong,

M.A. Haddad, W. Ubachs

LaserLaB, Vrije Universiteit Amsterdam

The molecular hydrogen ions (H2+, HD+,

etc.) consist of three elementary particles,

which interact according to the laws of

QED. Recently, theorists in the field have

advanced the QED description of the

molecular hydrogen ions to an accuracy

level at which fundamental particle pro-

perties, such as the proton-electron mass

ratio and the proton size, contribute sub-

stantially to the inaccuracy of calculated

level energies. Comparisons of theoretical

level calculations with accurate spectros-

copic data can therefore lead to improved

values of fundamental particle properties,

and stringent tests of QED. As molecular

hydrogen ions possess long-lived rovibra-

tional states, they are amenable to the

most accurate spectroscopic technique to

date, namely optical spectroscopy of

laser-cooled ions stored in a trap. Here

we report experimental progress towards

a new determination of the proton-elec-

tron mass ratio, based on high-resolution

rovibrational spectroscopy of laser-cooled

HD+, and towards a test of a recently-

found 5σ discrepancy between different

determinations of the proton size,

through radiofrequency spectroscopy of

HD+ hyperfine intervals.

Optical fiber frequency standard networks

J.C.J. Koelemeij, K.S.E. Eikema, W. Ubachs

LaserLaB, Vrije Universiteit Amsterdam

Since the 1950s microwave atomic clocks

have revolutionized society, enabling

technologies such as the Internet and

global navigation satellite systems

(GNSS). One prerequisite for such

technologies is that atomic clocks are

embedded within a ‘frequency standard

network’, so that clocks in various loca-

tions can be compared and synchronized.

Recent developments in high-resolution

laser spectroscopy have led to so-called

optical clocks performing at sub-10-17

accuracy, or 25 times better than ‘tradi-

tional’ atomic clocks, and further impro-

vement is anticipated. Such clocks have

tremendous potential for fundamental

physics tests, astronomy, navigation

and geodesy, provided that they becomeembedded within a network. Time transfer

through GNSS is not well-suited, how-

ever, as it is limited by microwave-clock

technology, and by disturbances due to

the earth’s atmosphere. Recently, several

European metrology labs demonstrated

transfer of optical clock signals with

10-19 accuracy over >100 km distance

using existing telecommunication optical

fibers. At LaserLaB we are preparing expe-

riments to disseminate the optical carrier

of a stable laser to other locations within

the Netherlands and Europe, possibly

using the SURFnet fiber network.

37

P29 P30

Spin drag in an optical trap

S.B. Koller, A. Groot, P. Bons, J. Vogels,

P. van der Straten

Nanophotonics, Utrecht University

We investigate the transport of different

spin species of ultra cold sodium atoms

in the hydrodynamic regime at finite

temperatures. This is the spin analogue of

charge transport in solid state physics. It

has a strong temperature dependence and

in a one-dimensional regime we may

observe spin charge decoupling. The

different spin species are locally created

by a fast RF sweep and drag is applied

with a magnetic gradient along the axis

of a far off resonant optical trap. We will

measure the drag coefficient as a func-

tion of temperature as well as density.

High Repetition Ultrafast ElectronBunches

Adam Lassise, P.H.A. Mutsaers, O.J. Luiten

Technische Universiteit Eindhoven

Sub-picosecond electron bunch creation

has, thus far, been realized with the use

of femtosecond lasers interacting with

photo-cathodes or very near an existing

EM cathode. We present a technique for

the creation of sub-picosecond electron

bunches without the compulsory use of

cumbersome femtosecond laser systems.

Using nothing more than a 30 keV SEM,

standard s-band rf-technology, and a slit;

sub-picosecond electron bunches are

created at a repetition rate of 6 GHz.

The standard s-band rf-technology is a

miniature, low power, dielectric filled

resonant cavity designed to operate in the

TM110 mode, deflecting the electrons in

one transverse direction, exactly as a

streak camera. The cavity is an in-house

design and build, requiring only 16 W

power to generate 1.3 mT magnetic field

to deflect the electrons in a manner that

is approximately linearly proportional to

the field. This allows for beam manipu-

lation and sub-picosecond electron

bunch generation with nominal growth

to the transverse brightness and emittan-

ce. Further beam characterization and

laser-electron measurements are in

development.

38

P31 P32

Femtosecond pulse shaping and quantum

control in multichannel molecular dyna-

mics studied by photoelectron-photoion coincidence imaging

Carl Stefan Lehmann, Daniel Irimia,

Arno Vredenborg, Wim G. Roeterdink,

Mohammed M. Rafiee Fanood,

Maurice H.M. Janssen

LaserLAB and Department of Chemistry,

Vrije Universiteit Amsterdam,

In laser excitation of molecules with

femtosecond pulses different multipho-

ton processes are easily induced leading

to electrons and various neutral and

ionic atomic and molecular fragments.

The most complete information on the

mechanism of molecular photodissocia-

tion and ionisation dynamics can be

obtained by photo-electron / photo-ion

coincidence imaging. From the data the

complete energetic correlations and

three-dimensional angular and energy

resolved distributions are obtained both

in the laboratory frame as well as the

recoil (molecular) frame. The energy cor-

relation of the electron and its coincident

ionic fragment enables us to distinguish

competing multiphoton processes.

We combine the coincidence imaging

technique with the nowadays well-esta-

blished pulse shaping technique. Pulse

shaping provides a tool to control the

reaction pathway, thereby controlling the

reaction outcome. In this contribution

the experimental set-up and the recent

experimental data on shaping the ultra-

fast induced dynamics will be presented.

Feshbach resonances in Fermi mixturesof ultracold 40K and 6Li

A. Ludewig1, T.G. Tiecke2,

F.M. Spiegelhalder1, J.T.M. Walraven1

1 Van der Waals-Zeeman Instiuut,

Universiteit van Amsterdam2 Harvard University, Cambridge, USA

We report on the measurement of

Feshbach resonances in ultracold Fermi-

Fermi mixtures of 6Li and 40K in an

optical dipole trap (ODT). In the same

trap we have realized degenerate spin

mixtures of 106 40K atoms at T=0.3(1)TF.

The cold atoms are loaded from two

separate two dimensional magneto-

optical traps (MOT). We realized for the

first time a 2D-MOT source for lithium,

yielding a large cold flux of up to 109/s.

After evaporation in an optically plugged

magnetic trap the atoms are loaded into

optical tweezers and transported over

21.5cm into a science cell where we mea-

sure Feshbach resonances using magnetic

field coils designed for high homogeneity.

We present results from measuring the

widths of Feshbach resonances in 6Li -40K mixtures.40K has a rich hyperfine structure

(F=9/2) and many Feshbach resonances

involving the different states are expec-

ted. We report on our progress exploring

Feshbach resonances in 40K and locating

resonances favourable for the investiga-

tion of many body states.

39

P33 P34

Coherent Control of Angular MomentumTransfer Dynamics in Resonant One-Photon Light-Matter Interaction

D. Malik

Radboud University Nijmegen

We demonstrate coherent control of

the ultrafast dynamics of the angular

momentum transfer in atomic rubidium

during a one photon excitation. It is

shown experimentally and theoretically

that angular momentum can be control-

led on a hundred femtosecond time scale

both resonantly and off-resonantly by a

polarization-shaped femtosecond laser

pulse, containing only linearly polarized

frequencies. The angular momentum in

the excited 5p state is probed via one-

photon ionization using velocity map

imaging. Transient dynamics of the

angular momentum is analyzed by time

dependent calculation of the Schrödinger

equation in the perturbative limit.

Magnetic effects in FeNi structurescodeposited with atom nanolithography

Thijs Meijer, Josh Beardmore,

Jeroen Franken, Mark Hoeijmakers,

Edgar Vredenbregt, Bert Koopmans,

Ton van Leeuwen

Eindhoven University of Technology

Atom nanolithography uses the dipolar

interaction of a resonant lightfield with

neutral atoms, to structure depositions

of neutral atoms with standing wave

lightfields. As this technology works only

for near resonant lightfields, it allows us

to structure an alloy (FeNi) where iron is

structured, whereas nickel remains uni-

form (fig 1a).

We can create arrays of 186nm period

nanolines (fig 1b) of up to 6nm high

over area’s of 250µm x 7mm. These

arrays show clear macroscopic magnetic

anisotropy. With MOKE microscopy we

looked at the magnetic switching of the

array of lines in the centre of a

400x400 µm field of with for a field

perpendicular (1c) or parallel (1d) to

the field, showing clear anisotropy.

40

P35 P36

Direct frequency comb excitation of the dipole forbidden clock transition intrapped calcium ions

J. Morgenweg1, A.L.Wolf1,2, J. Koelemeij1,

S.A. van den Berg2, W. Ubachs1,

K.S.E. Eikema1

1 LaserLaB, VU Amsterdam2 NMI van Swinden Laboratory

We recently demonstrated direct frequen-

cy comb spectroscopy on laser cooled

ions in a linear Paul trap for the first

time. Now we show that, in a similar

setup, it is even possible to excite a

dipole-forbidden transition, despite the

low power per unamplified comb mode

of ~1µW. Using a combination of shel-

ving and single ion imaging, we achieve

a near 100% detection probability.

As a proof of principle, the

4s2S1/2 – 3d2D5/2 clock transition in

calcium has been measured at sub-MHz

accuracy, in accordance with previously

reported results; a Hz-level accuracy

seems feasible, if a Hz-level linewidth

frequency comb is used and the ions are

trapped in the Lamb-Dicke regime.

Small focus production schemes forobservation and control of dipole-dipoleinteractions between Rydberg atoms

R.G. Newell, Y.F.V. Leung,

C.S.E. van Ditzhuijzen, A.F. Tauschinsky,

S.M. Whitlock,

H.B. van Linden van den Heuvell

Van der Waals-Zeeman Instituut,

Universiteit van Amsterdam

The characteristics of dipole-dipole inter-

actions between Rydberg atoms make

them highly suited to quantum informa-

tion applications [1].

Previously our group has studied such

interactions between mesoscopic, spatial-

ly separate ensembles of distinct Rydberg

states; observing and manipulating

resonant energy transfer using static

and oscillating electric fields [2, 3].

We will now study and control such

processes in a fully coherent regime. We

present a number of possible schemes

based upon small focus production

volumes; enabling studies in intermediate

regimes not accessible by more common

trapping based methods.

[1] D. Jaksch et al., Phys. Rev. Lett. 85, 2208

(2000).

[2] C. S. E. van Ditzhuijzenet et al., Phys. Rev.

Lett. 100, 243201 (2008).

[3] A. F. Tauschinsky et al., Phys. Rev. A 78,

063409 (2008).

41

P37 P38

High precision UV measurements in CO, towards a laboratory test of the time-invariance of µ

Adrian J. de Nijs, Wim Ubachs,

Hendrick L. Bethlem

LaserLaB Vrije Universiteit Amsterdam

The metastable a3Π state of CO has been

found to have favourable properties for

testing the time-invariance of physical

constants. Due to a fortuitous level struc-

ture, an incidental degeneracy occurs

between rotational states in the different

spin-orbit ladders, to be specific, between

the J=8, Ω=0 and the J=6, Ω=1. Due to

this degeneracy, the 2-photon microwave

transition connecting these two states is

highly sensitive to a possible time-varia-

tion of the proton-to-electron mass ratio,

µ, and the fine structure constant, α. We

are planning a molecular beam experi-

ment to measure this transition.

As a first step, spectroscopic measure-

ments have been performed on the

a3Π → Χ1Σ+ transition, using a narrow-

band UV source around 206 nm, calibra-

ted using a frequency comb. We have

recorded several transitions in 12C16O,13C16O and 12C18O at a MHz precision,

corresponding to a relative accuracy of

10-10. The measured isotope shift

confirms the calculated sensitivity to

a possible variation of µ.

Improving Electromagnetically InducedTransparency in Si:GaAs by SelectivePumping of Nuclear Spins

A.R. Onur, M. Sladkov, A.U. Chaubal,

C.H. van der Wal

University of Groningen

We recently observed Electromagnetically

Induced Transparency (EIT) with an

ensemble of donor-bound electrons in

GaAs. EIT is a quantum optical effect

that relies on a destructive quantum

interference in a resonant Raman scheme

(see figure) and gives access to strong

coherent field-matter interactions. High

quality EIT requires a long electron-spin

dephasing time, which is in this system

limited by hyperfine coupling between

each electron spin and ~105 fluctuating

nuclear spins. We study how dynamical

nuclear polarization that results from the

EIT control scheme itself can pump away

these nuclear spin fluctuations, and thus

turn EIT into a self-improving effect.

Energy levels of a donor-bound electron system

(D0, Zeeman-split spin states) with optical driving

to a donor-bound trion state (D0X).

42

P39 P40

Fragmentation chemistry of anionic peptides elucidated by IR spectroscopy

Jos Oomens, Jeffrey D. Steill, Britta Redlich

FELIX facility, FOM Rijnhuizen

While peptide sequencing by collision

induced dissociation tandem mass

spectrometry (CID MS) has found wide

application in biochemistry, the under-

lying reaction chemistry remains an

issue of lively debate. In recent years, the

application of infrared (IR) spectroscopy

to CID fragment ions of protonated

peptides has provided important new

information on their molecular structu-

res. Here we present the first infrared

spectra of a mass-selected peptide anionand one of its CID fragments. These

experiments suggest a carboxylate anion

for [M – H]– and an amide deprotonated

(amidate) structure for the a3 fragment

anion [M – H – CO2]– (see figure). The

amidate carbonyl stretching frequency

occurring around 1555 cm-1 has been

confirmed by additional spectra of the

conjugated base of N-methylacetamide,

which serves as a model for the deproto-

nated amide linkage.

Atom-light interactions in plasmonicnanostructures

D. van Oosten, B.O. Mussmann,

F. Kamphorst

Debye Institute for NanoMaterials Science,

Utrecht University

In nanoplasmonics, subwavelength sized

structures in metal films are used to

launch and control surface plasmons

polaritons (SPPs). These are very suitable

for integration in nanophotonic devices

and can enhance many optical detection

processes. In the field of ultracold atoms,

lasers are used to cool and trap atoms. As

the atoms are tightly controlled, they are

powerful experimental tools for studies

in condensed matter physics, quantum

information processing and cavity

quantum electrodynamics.

We will combine nanoplasmonics with

ultracold atoms, by trapping atoms in

the near-field of metal nanostructures, to

study and control the coupling between

atoms, light and SPPs.

The proposed experimental setup. An array of

sub-wavelength sized holes in a metal film is

illuminated with laser light. The near-field of the

holes is used to trap ultracold atoms.

43

P41 P42

Single-shot femtosecond electron diffraction

P.L.E.M. Pasmans, T. van Oudheusden,

O.J. Luiten

Eindhoven University of Technology

Ultrafast electron diffraction (UED)

enables studying dynamics of non-

equilibrium structures, like phase transi-

tions and conformation changes, with

both spatial and temporal resolution at

the atomic level (~0.1 nm and ~100 fs).

To acquire a diffraction pattern of suffi-

cient quality typically 106 electrons are

required. So far in UED experiments

multiple shots are used to build up a

high-quality diffraction pattern, limiting

the applicability of UED to reversible

processes. Single-shot operation requires

packing ~106 electrons in a single bunch.

Unfortunately, the strong repelling

Coulomb forces inevitably broaden the

bunch.

In our setup we accelerate electron

bunches to 100 keV and reverse the

bunch expansion by injection onto the

oscillatory field sustained in a radio-

frequency (RF) cavity. In this way we

have realized sub-100 fs, 0.1pC, 100keV

electron bunches, which thus fulfill all

requirements for single-shot femtosecond

electron diffraction. Using only a single

electron bunch we demonstrate single-

shot diffraction of a polycrystalline gold

film. Currently we are improving the

bunch length characterization and we are

preparing our first pump-probe time-

resolved UED experiments.

Engineering light-matter interaction atthe single-photon level

W. Pfaff1, T. van der Sar1, T.H. Oosterkamp2,

D. Bouwmeester2, R. Hanson1

1 Kavli Insitute of Nanoscience,

Delft University of Technology2 Leiden Institute of Physics, Leiden University

The interaction between a single photon

source and its electromagnetic environ-

ment is a central theme in quantum

optics. Defect centers in diamond, parti-

cularly the Nitrogen-Vacancy (NV)

center, are extremely stable sources of

single photons. We have developed a

technique to accurately position a

diamond nanocrystal containing one

NV center with nanometer precision [1].

In this poster, we describe the nanoposi-

tioning process and the experimental

progress towards exciting applications

involving the efficient coupling of single

photons to plasmonic waveguides and

photonic crystal cavities (figure). These

experiments could lead to efficient single

photon generation, observation of spin-

photon entanglement, and all on-chip,

‘dark’ optics.

[1] T. van der Sar et al., Applied Physics Letters,

94, 173104 (2009).

44

P43 P44

Fragmentation and ionization dynamicsof Argon clusters upon keV highly charged ion interaction

J. Postma, R. Hoekstra, T. Schlathölter

KVI Atomic Physics, University of Groningen

The interaction of Argon Van-Der-Waals

clusters with highly charged ions

(HCI) is a line of research currently

being explored in the KVI Atomic and

Molecular Physics group. Previous

research has proven that, in contrast to

other ionization techniques, HCI can lead

to strong charge localiza-tion within the

cluster.

We build a supersonic jet apparatus

as a source for a wide variety of

Van-Der-Waals clusters. This source is

capable of operating under a wide range

of scaling parameters Γ*, which is

directly correlated to the mean clustersize

in the jet.

Of great interest, for one, is the cluster

size dependence of the interaction pro-

ducts. To date it is not known if small

clusters are able to survive intact after

interaction. We have tentative evidence

that indeed they do so.

With the installation of a recoil ion

momentum spectrometer in the near

future we will be able to make full kine-

matical reconstructions of these type

of interactions.

Momentum imaging studies of dissociative electron attachment to polyatomic molecules – I

N Bhargava Ram#, V S Prabhudesai,

E Krishnakumar

Tata Institute of Fundamental Research,

Mumbai, India# Current Affiliation:

Vrije Universiteit, Amsterdam

Studies on low energy electron - molecule

collisions has seen a resurgence conside-

ring the role it plays in the area of che-

mical control using electrons, radiation

therapy, modeling plasma processes etc.

Collisions of low energy electrons

(<15 eV) with neutral molecules can lead

to electron capture and formation of

negative ion resonances. These negative

ion resonances usually decay by auto-

detachment (where the extra electron

is ejected) or dissociate into an anion

fragment and one or more neutrals. The

latter process is known as Dissociative

Electron Attachment (DEA). Using the

novel technique of velocity map imaging,

we studied the negative ion resonances in

polyatomic molecules, namely – Water,

Hydrogen Sulphide, Ammonia, Methane,

Formic Acid and Propyl Amine by measu-

ring the kinetic energy and angular

distribution of the fragment anions.

In part I here, the details of the DEA

process in Water, Hydrogen Sulphide and

Ammonia will be presented.

45

P45 P46

Momentum imaging studies of dissociative electron attachment to polyatomic molecules – II

N Bhargava Ram#, V S Prabhudesai,

E Krishnakumar

Tata Institute of Fundamental Research,

Mumbai, India# Current Affiliation:

Vrije Universiteit, Amsterdam

In part II here, the details of the kinetic

energy and angular distribution of

fragment ions from DEA in Methane,

Formic Acid and Propyl Amine will be

presented.

The studies on Formic Acid and Propyl

Amine (molecules containing more

than one functional group) follow the

measurements on precursor molecules

like water, ammonia and methane. We

compare the results from the measure-

ments on these bigger molecules vis-à-vis

the smaller precursor molecules and look

for similarities/dissimilarities in the

dissociation dynamics due to electron

attachment. It is seen that the local func-

tional group determines the dissociation

dynamics to the extent that it is manifes-

ted in the angular distributions and is

independent of the symmetry of the

whole molecule.

Trapping of 225Ra for electric dipolemoment searches

B. Santra, U. Dammalapati, K. Jungmann,

H.W. Wilschut, L. Willmann

KVI, University of Groningen

Searches for permanent electric dipole

moments (EDMs) have a discovery

potential of not yet known sources of

violations of the discrete symmetries

parity and time reversal. Radium isotopes

exhibit uniquely high intrinsic sensitivi-

ties due to their particular atomic and

nuclear structure. The experiment

requires cooling and trapping of neutral

radium atoms. In a first step radium

atoms have to be collected efficiently in

a magneto optical trap. We present our

setup which requires multiple lasers for

slowing, cooling and repumping. In a

second step the atoms have to be

transferred to an optical dipole trap. We

calculate the wavelength dependence of

the parameters of an optical dipole trap,

based on the known atomic structure

of Ra. Operating at a magic wavelength

is crucial for the efficient transfer of the

atoms from the MOT to the dipole trap.

46

P47 P48

Coherent radiation reaction effects inlaser-vacuum acceleration

Smorenburg, Kamp, Geloni, Luiten

T.U. Eindhoven

Need for high-brightness electron

bunches has lead to intensive research

on table-top laser-based accelerators.

Suggested laser-vacuum acceleration

schemes exploit the ponderomotive force

of a laser pulse, but these are problematic

because the ponderomotive force expells

the bunch out of the laser beam before

appreciable acceleration has occured.

An often neglected effect in laser-vacuum

acceleration is radiation reaction (RR).

Laser-irradiated bunch electrons scatter a

fraction of the light due to their oscilla-

tory motion in the optical field, known

as Thomson scattering. The accompany-

ing recoil from the scattered light is the

RR, which usually affects the electron

motion neglicably. However, when the

bunch is subwavelength, the electrons

scatter coherently, yielding a strongly

enhanced RR which can accelerate the

bunch significantly.

We show that such coherent RR acts as

a radiation pressure in the laser beam

direction, and as a viscous force trans-

versally. Thus coherent RR both increases

bunch acceleration and opposes the pro-

blematic transversal ponderomotive force,

showing its relevance in laser-vacuum

acceleration schemes. Moreover, by

amplifying the RR, scattering bunches

are an experimentally accessible model

of point charges.

Preparation and manipulation of cold molecules

Dimitrios Sofikitis

Laboratoire Aimé Cotton, CNRS

Université Paris-Sud, Orsay, France

In the last years, preparation of atomic

samples in low (~µK) and ultra-low (nK)

temperatures has been established tech-

nologically and has been used in a variety

of scientific and even industrial applica-

tions. Molecules have been left out of

these exciting developments, despite the

great variety of potential applications.

The reason that molecules are not suita-

ble for optical pumping, which lies in the

heart of the standard laser cooling tech-

niques, due to the existence of additional

internal degrees of freedom correspon-

ding to the molecular vibration and

rotation.

The technique of photoassociation has

been recently used for the preparation of

translationally cold Cs2 molecules in

their ground electronic state. Moreover,

broadband radiation has been used to

simultaneously excite all the molecular

population; repetition of this interaction

can lead to a process which corresponds

the optical pumping in atoms. Finally,

the removal of frequencies that excite the

ground vibrational level converts it to a

‘dark’ state of the system and leads to

accumulation of molecular population to

this level, demonstrating laser cooling of

molecular vibration.

47

P49 P50

New methods for the productionand detection of polarized atoms

Dimitrios Sofikitis

IESL-FORTH

Heraklion Crete –GREECE

Control over spin and, more generally,

over quantum angular momentum has

led to many technological advances, such

as NMR, medical imaging, and has allo-

wed the study of many spin-dependent

phenomena, in the fields of nuclear,

atomic, molecular and surface scattering.

Almost in all cases, the objective is to

create simple distributions of angular

momentum since it is in those cases

where angular momentum properties can

become acroscopically apparent and of

technologic and scientific importance.

This work originates in the study of a

recently developed technique for the pro-

duction of spin polarized halogen atoms

as well as hydrogen atoms from molecu-

lar photodissociation of hydrogen halides.

The first part is dedicated in the develop-

ment of a new technique for the detec-

tion of spin polarization in hydrogen

atoms using Laser Induced Fluorescence

(LIF). As the technique of molecular

photodissociation suffers from a depola-

rization phenomenon that minimizes

the amount of the final, time averaged

atomic polarization achieved, the effort

to minimize this effect results in a new

technique for the production of polarized

atoms via the hyperfine interaction.

How oxygen absorbs solar light in a real atmosphere

Frans Spiering1, Masha Kiseleva2,

Wim J. van der Zande1

1 IMM, Radboud Universiteit Nijmegen

2 St Petersburg State University

Absorption of light by molecules at

ambient pressures is affected in multiple

ways. Elastic collisions induce lifetime

broadening as well as Dicke narrowing,

inelastic collisions induce line mixing,

a process which takes into account that

molecules inelastically collide. Using

cavity ring down spectroscopy we

quantify these processes to a 1% accuracy

level for oxygen-oxygen and for oxygen-

nitrogen collisions by looking in between

absorption lines where it takes about

100 km of pure oxygen to get significant

absorption. This accuracy is required to

avoid systematic errors to occur in the

retrieval of trace gasses from satellite

data.

48

P51 P52

Integrated microspectrometer for biological applications

A.J. Stephenson1, E.T. Garbacik1, M. Jurna1,

J.P. Korterik1, J.L. Herek1, C. Otto2,

H.L. Offerhaus1

1 Optical Sciences Group, MESA + Institute

for Nanotechnology;

2 Medical Cell Biophysics, MIRA institute for

Biomedical Technology and Technical

Medicine, University of Twente

Spontaneous Raman spectroscopy is an

inelastic scattering process used to probe

molecular vibrations. Coherent anti-

Stokes Raman scattering (CARS) is a

nonlinear multi-photon scattering pro-

cess usually used to probe one specified

molecular vibration. Each molecule has a

unique set of vibrational frequencies and

hence a unique Raman spectrum. This

uniqueness allows Raman scattering as

well as CARS to accurately identify and

distinguish molecules. Raman has many

advantages, including the absence of a

non-resonant background and the ability

to look at multiple molecular vibrations

simultaneously. However, CARS scans a

sample much more quickly and avoids

the fluorescent background. By combi-

ning a CARS microscope and a Raman

spectrometer, our new set-up highlights

the advantages of both techniques to

better understand our samples.

Spatially resolved excitation of Rydberg atoms on an atom chip

Atreju Tauschinsky, et al.

Universiteit van Amsterdam

We demonstrate spatially resolved, coherent

excitation of Rydberg atoms on an atom

chip. We use electromagnetically induced

transparency (EIT) to measure energy level

shifts for Rydberg atoms near the gold

coated chip surface. These shifts and their

distance dependence are explained with a

simple model for the electric field produced

by a localized patch of Rubidium adsorbates

deposited on the chip surface during experi-

ments. The observed widths of the EIT reso-

nances remain narrow and independent of

atom-surface distance down to ~20µm. Our

results are an excellent starting point for

further studies of atom-surface interactions,

many-body physics and quantum information

science involving long-range interactions of

Rydberg atoms and collective excitations in

arrays of mescosopic ensembles.

A. Tauschinsky et al., PRA 81, 063411(2010);

S. Whitlock et al., PRL 104, 120402(2010)

49

P53 P54

On-line excited-state laser spectroscopyof trapped short-lived Ra+ Ions

O.O. Versolato, G.S. Giri, L.W. Wansbeek,

J.E. van den Berg, D.J. van der Hoek,

K. Jungmann, W.L. Kruithof,

C.J.G. Onderwater, B.K. Sahoo, B. Santra,

P.D. Shidling, R.G.E. Timmermans,

L. Willmann, H.W. Wilschut

University of Groningen,

Kernfysisch Versneller Instituut

The radium ion is a promising candidate

for high precision experiments. Atomic

parity violation can be measured in a

single trapped and laser cooled radium

ion [1]. Ultra-narrow transitions in this

system can be exploited to realize a high

precision frequency standard [2]. As an

important step towards such experi-

ments, excited-state laser spectroscopy

was performed with on-line produced

short-lived trapped 212,213,214Ra+ ions

[3]. These values provide a benchmark

for the required atomic theory. Work

towards laser cooling is underway. On-

line production of 209,210,211Ra+ ions

was achieved; spectroscopy of these

isotopes is planned.

[1] L.W. Wansbeek et al., Phys. Rev. A 78 (2008)

050501(R).

[2] O.O. Versolato et al., in preparation.

[3] O.O. Versolato et al., Phys. Rev. A 82 (2010)

010501(R).

Controlling one-dimensional spin motion with state-dependent potentials

P. Wicke, A.L. Hoendervanger,

S.Whitlock, N.J. van Druten

University of Amsterdam

Ultracold gases offer unparalleled oppor-

tunities to probe and explore quantum

many-body physics, with experiments

providing an ever-growing ability to tune

and control key parameters such as

temperature, density, interactions and

even dimensionality. Of great interest are

quantum gases with a spin degree of

freedom, relevant for our understanding

of phenomena such as spin waves,

spin-“charge” separation and the relation

between superfluidity and magnetism. In

this work we prepare coherent superposi-

tions of both spin and motional degrees

of freedom in a one-dimensional Bose

gas and directly image non-equilibrium

spin dynamics following a sudden change

in the system parameters.

We demonstrate a new way to tune inter-

actions in a state-dependent way using

radio-frequency dressed potentials. This

provides experimental control over the

resulting spin dynamics and we show

that this enables access to the point of

spin-independent interactions where

exact quantum many-body solutions are

available and to the point where spin

dynamics are frozen. In the future we

plan to extend our studies to the strongly

interacting regime by adding a one-

dimensional optical lattice along the

weak axis of the magnetic trap.

50

P55 P56

A spectral calibration scheme for terahertz FEL radiation

F.J.P Wijnen1, G. Berden2, A.J.A. van Roij1,

W.J. van der Zande1, R.T. Jongma1

1 Molecular and biophysics, Institute for

Molecules and Materials,

Radboud University Nijmegen2 FOM instituut Rijnhuizen

At the Radboud University in Nijmegen,

the Netherlands, we are constructing

the free electron laser FLARE, which will

operate in the terahertz gap, generating

light from 0.2 to 3 THz (100 – 1500

micrometer wavelength). FLARE operates

in a short pulse mode with bandwidth

limited pulses and a spectral resolution

about 1%, but also in a spectroscopic

mode with a bandwidth of 10-5. The

spectroscopic mode will be realised by

generation of a 3 GHz frequency comb in

combination with extra-cavity filtering

selecting a single mode of the frequency

comb. One of the challenges for this sys-

tem is to perform the spectral calibration

of the generated light, in particular for

the spectroscopic mode, over the large

spectral range that is difficult to access

directly. Upconversion of the THz light to

the near-infrared (NIR) spectral region,

by sum and difference frequency genera-

tion with a NIR laser, allows the calibra-

tion to be performed with standard opti-

cal detectors, as has been shown at the

cw UCSB-FEL. In this contribution, we

present the results of experiments perfor-

med at FELIX that demonstrate the high

sensitivity of this technique, and we dis-

cuss new schemes to extend this upcon-

version technique for the spectroscopic

mode of FLARE.

Towards coherent lensless X-ray microscopy with a table-top setup

Stefan Witte1,2, Daniel Noom1,

Wim Ubachs1, Kjeld Eikema1

1 LaserLaB, Vrije Universiteit Amsterdam2 JILA, University of Colorado, Boulder, USA

Microscopy is an essential tool in many

branches of science. The ability to do

microscopy using extreme-ultraviolet

(XUV) and soft-X-ray radiation is intri-

guing, as it would allow a much higher

resolution.

Soft-X-ray microscopy can provide

element-specific contrast on condensed-

matter samples, while the ‘water-window’

wavelength range enables imaging of

water-immersed biological samples at

unprecedented resolution.

Since high-quality soft-X-ray lenses do

not exist, we pursue lens-less imaging

techniques such as diffraction imaging or

Fourier-transform holography for captu-

ring images. This requires highly coherent

radiation, which will be produced

through high-harmonic generation, using

powerful few-cycle laser pulses from a

terawatt-class optical parametric chirped-

pulse amplifier system.

We will present plans for constructing

such a table-top soft-X-ray microscope,

and discuss ideas for experiments with

this unique system.

51

P57 P58

Measurements on partiallycoherent light

J. Woudenberg, H. Di Lorenzo Pires,

M.P. van Exter

Huygens Laboratory, Leiden University

The orbital angular momentum (OAM)

of light has been extensively studied in

coherent beams. Recently, this concept

was generalized to partially coherent light

as well. We present the first measure-

ments of the OAM spectrum of a partial-

ly coherent beam. For this purpose, we

have built a source of variable coherence

and measured its OAM spectrum, using a

Mach-Zehnder interferometer with an

image rotator in one of its arms.

In a second experiment, we demonstrate

how a spiral phase plate (SPP) can

change the spatial coherence of the

beam. This coherence can be directly

visualized on a CCD located behind the

same interferometer (see figure). We

show, in particular, how the SPP can

create or eliminate phase singularities in

the two-point coherence function.

D. Zhao1, M. Ali Haddad1, N. Wehres2,

H. Linnartz1,2, W. Ubachs1

1 Vrije Universiteit, amsterdam 2 Leiden University

The carbon chain species, with the form

of XmCnYl (X, Y =H, N, O, S…), play an

important role in the plasma chemistry,

combustion process and astrochemistry.

The laboratory electronic spectra of the

carbon chain molecules can provide a

database for the astrophysical search.

Systematic investigations on the absorp-

tion bands of the carbon chain species

through a supersonically expanding

hydrocarbon plasma in the 440-540 nm

region were carried out using the cavity

ringdown spectroscopy. More than 92

absorption bands of the carbon chain

molecules were recorded with reasonably

high resolution. Based upon the previous

study and spectral analysis in this work,

about 56 bands can be assigned as the

electronic transitions of linear and

nonlinear molecules, such as

C6H, HC7H, C9H3…, and so on. The

spectra of the carbon chains obtained in

this work were compared to the newest

reported DIBs to find out their

astrophysical relevance.

Cavity ringdown absorption spectroscopyof the carbon chain molecules

52

P59 P60

Detection of volatile compounds inhuman breath using a femtosecond frequency comb laser

M. G. Zeitouny1, A. Reyes Reyes1,

N. Bhattacharya1, S.T. Persijn2, H.P. Urbach1

1 Optics research group,

Delft University of Technology

2 VSL, Delft

Over the past decade, numerous scien-

tific studies have dealt with the investi-

gation of biogenic trace gases in human

breath. It is shown that the exhaled

breath contains several hundred of

volatile compounds, some of them are

considered to be disease markers or

biomarkers. These biomarkers are present

in volume fractions of the order of one

part per billion (ppb) or lower. Accurate

and precise measurement of relevant

molecules is still a challenge. New

spectroscopic techniques have emerged

with the advent of carrier envelope stabi-

lized pulse sources. In this work, we will

present a novel spectroscopic setup for

the measurement of volatile compounds

in human breath. This setup consists of

a femtosecond frequency comb laser and

a Virtually Imaged Phased Array (VIPA)

spectrometer. Spectroscopic results from

the analysis of some relevant molecules

will be discussed showing the capabilities

of the VIPA spectrometer.

Switching Casimir forces with Phase Change Materials

G. Palasantzas, et al.

University of Groningen

We demonstrate here a controllable varia-

tion in the Casimir force (Fig. 1) [1].

Changes in the force of up to 20% at

separations of ~100 nm between Au and

AgInSbTe (AIST) surfaces were achieved

upon crystallization of an amorphous

sample of AIST. This material is well

known for its structural transformation,

which produces a significant change in the

optical properties and is exploited in opti-

cal data storage systems. The finding paves

the way to the control of forces in nano-

systems, such as micro- or nanoswitches

by stimulating the phase change transition

via localized heat sources [1, 2].

[1] G. Torricelli, et al., Switching Casimir forces

with Phase Change Materials, Phys. Rev. A 82,

010101 (2010) / Rapid Com.

[2] New Scientist: Casimir effect put to work

as a nano-switch /

http://www.newscientist.com/article/

dn19120-casimir-effect-put-to-work-as-

a-nanoswitch.html

Fig. 1 Casimir force gradient measurement for the crystalline () and amorphous () phase [1].

The upper inset shows the relative difference between the two force states, and in comparison

with theory prediction (using as input the optical data of Fig.2) assuming flat surfaces [1].

53

Workgroups

AMSTERDAM (AMOLF)Prof.dr. H.J. Bakker Ultrafast SpectroscopyProf.dr. Misha.Bonn Biosurface SpectroscopyProf.dr. L. Kuipers Nano-opticsProf.dr. A. Lagendijk Photon ScatteringDr. T. Shimizu Systems biology, bio imagingDr. J. Gómez Rivas* Nanowire PhotonicsDr. F. Koenderink Resonant NanophotonicsDr. G. Koenderink Soft Matter Imaging* High Tech Campus Eindhoven

AMSTERDAM (Universiteit van Amsterdam)Prof.dr. T. Gregorkiewicz Semiconductors microphotonicsDr. R.Sprik Complex soft matter physicsDr. N.J. van Druten Quantum Gases, Atom Optics, Quantum InformationDr. T.W. HijmansProf.dr. H.B. van Linden van den HeuvellProf.dr. G.V. ShlyapnikovDr. R.J.C. SpreeuwProf. dr. J.T.M. Walraven

AMSTERDAM (Vrije Universiteit)Prof.dr. W. Ubachs Frequency metrology and variation of fundamental constants,Dr. W. Vassen laser cooling and Bose-Einstein condensation, high-intensityDr. K.S.E. Eikema ultrafast lasers and x-ray generation, spectroscopy of small Dr. H.L. Bethlem molecules (of atmospheric and astrophysical interest), XUV

laser spectroscopy. Prof. dr. M.H.M. Janssen Ultrafast molecular photodynamics, photoelectron-photoion Prof. dr. S. Stolte coincidence imaging, quantum state-to-state imaging of

oriented molecules, quantum control and pulse shapingProf.dr. J.F. de Boer Optical Coherence Tomography, spectroscopy

DELFT (Technische Universiteit)Prof. dr ir J.J.M. Braat Prof. Dr. P.C.M. PlankenDr. S.F. PereiraDr. F. BociortDr. N. BhattacharyaDr. A.J.L. AdamDr.ir. R. Hanson

Prof.dr. T. Visser (theory)

Terahertz imaging & spectroscopyOptical recording, near and far field microscopyOptical design, lithographyOptical aperture synthesisTerahertz imaging & spectroscopy

Quantum science in the solid state, quantum information, diamond defect centersNonlinear dynamics of diode lasers, semiconductor optical ampifiers, quantum optics of semiconductors, near field optics and coherence theory

54

Workgroups

EINDHOVEN (Technische Universiteit)Prof.dr. K.A.H. van LeeuwenDr. ir. G.J.H. BrussaardDr. ir. O.J. LuitenDr. ir. S.J.J.M.F. Kokkelmans (theory)Dr. ir. P.H.A. MutsaersDr.Ir. E.J.D. Vredenbregt

ENSCHEDE (Universiteit Twente)Prof.dr. K.-J. BollerDr. P.J.M. PetersDr. F.A. van GoorDr. H. M. J. BastiaensDr. P.J.M. van der Slot

Prof.dr. J.L. HerekDr. H.L. Offerhaus

Prof.dr. V. SubramaniamDr. M.L Bennink Prof.dr. Carl Figdor Dr H. Kanger Dr. R. Kooyman Dr. I. Segers-Nolten Prof.dr. L.W.M.M. TerstappenDr. C. Otto Dr. R. Schasfoort Dr. W. SteenbergenDr. S. ManoharProf.dr. A.J.G.M. (Ton) van Leeuwen Prof.dr. W.L. VosDr. A.P. MoskPepijn PinkseProf. Dr. M PollnauDr. S. Garcia BlancoDr. M. HammerDr. H. HoekstraDr. R. De RidderDr. K. Worhoff

Ultra cold plasma’s, bright ion and electron beams, atom optics, nanostructures by atom lithography, Compact (laser-driven) electron accelerators; generation of collective radiation (THz to XUV), including FEL physics; femtosecond-pulse physics, cold atomic interactions, quantum gase

Laserphysics and nonlinear optics, solid state lasers, excimer lasers, free electron lasers, optical parametric oscillators, laser wakefield acceleration, nonlinear pulse propagation in photonic crystals, frozen light, mid-IR molecular detection, high power diode lasers, laser material processingBiomolecular control, field shaping, coherent control,nonlinear/vibrational spectroscopy/microscopy, nanophotonics, plasmonic structures, near-field probe microscopy.Nano biophysics, genomic, proteomics, spectroscopy

Medical cell biophysics, nonlinear spectroscopy and microscopy. Raman imaging Microfluidics.

Biomedical photonic imaging, tissue imaging acoustic imaging and OCT.

Photonic crystals, scattering and localization

Applied NanophotonicsIntegrated optical microsystems

55

Workgroups

GRONINGEN (Kernfysisch Versneller Instituut)Prof.dr.ir. R. HoekstraDr. T. Schlathölter

Prof.dr. K. JungmannProf.dr. H. WilschutDr. L. WillmannDr. G. Onderwater

GRONINGEN (Rijksuniversiteit Groningen)Prof.dr. ir. P.H.M. van LoosdrechtDr. M.S. PchenichnikovProf.dr. H.A.J. MeijerDr.Ir. E.R.Th. Kerstel

Prof.dr. J.KoesterDr. T. la Cour JansenDr. V.A. MalyshevProf.dr. M. A. LoiProf.dr. ir. C.H. van der Wal Prof.dr. H.A.J. Meijer

Prof.dr. A. van Oijen Prof.dr. B. Poolman

LEIDEN (Universiteit Leiden)Prof.dr. J.P. WoerdmanDr. M.J.A. de DoodDr. E.R. ElielDr. M.P. van ExterProf. G.W. 't HooftProf.dr. D. Bouwmeester

Prof.dr. G. Nienhuis (theory)Prof.dr. E.J.J. GroenenProf.dr. S.L. VölkerProf.dr. M. OrritDr. P. GastDr. M.I. HuberProf.dr. C.W.J. Beenakker (theory)Prof.dr. G.J. KroesProf.dr. A.W. KleynDr. H.V.J. Linnartz

Radiation damage in biomolecular systems, Highly-charged ion physics, reaction microscopy, laser cooling and trapping,Atom Trap Trace Analysis, atomic processes at surfacesProduction of short-lived ions and atoms, ion/atom trapping,alkali/alkali earth trapping, atomic spectroscopy,fundamental interactions, search for electric dipole moments

Optical Condensed Matter PhysicsMultidimensional femtosecond optical spectroscopyHigh-precision isotope ratio determination using optical spectroscopy and applications in bio-medicine, palaeoclimatology and atmosphere physics.Theory of Condensed Matter

Photophysics of Organic Semiconductors & Nano-MaterialsPhysics of Quantum DevicesHigh-precision isotope ratio determination using optical spectroscopySingle-Molecule BiophysicsMembrane Enzymology

Quantum entanglement, two-photon optics, spatial coherence, nonlinear photonic crystals, sub-wavelength &metal optics

Macroscopic entanglement, semiconductor quantum physics (spintronics)Optical traps, light forces, quantum informationSingle-molecule physics, Electron Paramagnetic Resonance, Spectral hole burning

Mesoscopic physics, wave chaos, random mediaQuantum chemistry, Atmospheric physicsSurface physicsLaboratory astrophysics

56

Workgroups

NIEUWEGEIN (FOM Instituut voor Plasmafysica RIJNHUIZEN)Dr. A.F.G. van der MeerDr. G. BerdenDr. B. RedlichDr. J. OomensDr. J.M. BakkerDr. A.M. Rijs

NIJMEGEN (Radboud Universiteit Nijmegen)Prof.dr. D.H. ParkerDr. F.J.M. Harren

Prof.dr. Th. Rasing

Dr.ir. G.C. GroenenboomProf.dr.ir. A. van der Avoird (theory)Prof.dr. J.J. ter MeulenDr. N. Dam

Prof. dr. W.J. van der ZandeProf. dr. W.L. MeertsDr. R.T. Jongma

UTRECHT (Universiteit Utrecht)Prof. dr. P. van der StratenDr.ir. J.M. VogelsDr. D. van OostenProf.dr.ir. H.T.C. Stoof

Dr. R.A. Duine

FEL physics, generation and application of infrared/THz radiation

Molecular physics. infrared ion spectroscopy and structure, conformation selective spectroscopy, mass spectrometry, biomolecules, metal clusters, astrochemistry

Laser physics, molecular photodissociation, atmosheric processes, trace gas detection, medical and biological applicationsNonlinear optics, time-resolved laser spectroscopy, light scattering, magnetic, polymeric and liquid crystallinematerials, atom lithographyMolecular interactions and light-induced processes

Laser diagnostics, combustion processes, diesel engines, gas flow dynamics, diamond deposition Molecular collision dynamicsBiomolecular structure, Molecular and atmospheric Physics, THz generation, detection and applications to biomolecules and bio-mimetics, Free Electron Laser under construction.

Laser manipulation of atoms, Bose-Einstein condensation, Atom opticsCold atom nanophotonicsDynamics of Bose-Einstein Condensates, Quantum Effects inDegenerate Fermion and/or Boson gasesSpintronics

Design: Final Design

Print: Janssen Repro Nijmegen

This meeting is organized under the auspices of the

NNV-section Atomic, Molecular and Optical Physics,

with financial support of the Dutch Science Foundation

and the Foundation FOM.

The program is compiled by:Herman Offerhaus Peter van der Straten

This meeting is organized under the auspices of the

NNV-section Atomic, Molecular and Optical Physics,

with financial support of the Dutch Science Foundation

and the Foundation FOM.