Experimental Atomic Physics Research in the Budker Group

• Tests of fundamental symmetries using atomic physics:• Parity

• Time-reversal invariance

• Permutation Postulate/Spin-Statistics Connection

• Temporal variation of fundamental “constants”

• Applied atomic spectroscopy• Sensitive magnetometry and electrometry

• Nonlinear optics with atoms

• Optical properties of superfluid helium

• “New” atomic energy levels

• Properties of complex atoms: the rare earths, Ba

Group Demographics and Philosophy

• 6 graduate students

• 1 - 3 undergrads

• 2 staff scientists (1 senior, 1 junior)

• Part-time technician

• Lots of visitors from US and abroad

• Each student has their own project

• Lots of interactions within group

• Variety of experiences and techniques: lasers, optics, atomic beams and vapor cells, cryogenics, computer control and data acquisition, vacuum, electronics, theory, scientific writing and editing, …..

Further information:

• http://socrates.berkeley.edu/~budker

• budker@socrates.berkeley.edu

• Office: 273 Birge; labs: 217,219,221,230,241, and 245 Birge

Z

e

e

Weak interaction

(violates parity)) r ( = ) r (

Electromagnetic

interaction

(conserves parity)) r ( ) r (

Atomic Parity Nonconservation

Small Modifications of the Optical Properties of Atoms

Provides Unique Low-Energy Test of the Standard Model

CollimatorYtterbium atoms

Oven

PBC mirror

Parabolic reflector

Lightguide

BE

zx

y

Photo-multiplier tubes

Electric field plates

Magnetic field coils

408-nm light

649-nm lighte

Electric and magnetic fields define a handedness

PNC effects show up as dependence of atom-photon interaction on handedness

PNC Experiments

Two Experiments in Progress: Dysprosium (Z=66) and Ytterbium (Z=70)

How constant is the fine structure “constant” ?

Theories that unify gravity with other forces either

allow or necessitate variation

THEORETICAL

Laboratory:•H-maser vs. Hg+ microwave clock:

/< 3.7 10-14 /yr

•Rb vs. Cs microwave clocks:/< 1.1 10-14 /yr

•Hg+ optical vs. Cs microwave clocks:

/< 1.2 10-15 /yr

.

.

.

Geophysical:Oklo natural nuclear reactor

1.8 billion years ago: /< 10-18 /yr

.

Astrophysical:

[J. K. Webb, et al. , Phys. Rev. Lett. 87, 091301 (2001).]

/= (-7.2 1.8) 10-16 /yr

.

EXPERIMENTAL

A B

Ground State0

20,000

En

erg

y (c

m-1)

levels A and B are highly sensitive to

variations in

in dysprosium

’

~ 3-2000 MHz

atomic beam

PMT

atomic freq. standard

rf freq. generator

fluor.

E-field plates

~ 21015 Hz |/|

i.e. for |/| ~ 10-15 /yr

~ 2 Hz/yr

NONLINEAR MAGNETO-OPTICAL NONLINEAR MAGNETO-OPTICAL ROTATIONROTATION

Goal: Obtain highest possible sensitivity to magnetic fields.

Use laser light to polarize atoms:(1) Aligns magnetic dipole moments;(2) Creates preferred optical axis.

F = 1

F’ = 0

MF = -1 MF = 0 MF = +1

Magnetic moments precess in magnetic field:Optical axis rotates causes light polarization to rotate.

gFrel

gFrel)2

-1.0 -0.8 -0.6 -0.4 -0.2 -0.0 0.2 0.4 0.6 0.8 1.0

Magnetic Field (nT)

-10

-8

-6

-4

-2

0

2

4

6

8

10

Rot

atio

n A

ngl

e (m

rad)

Paraffin-coated cells smuggledin as Christmas ornaments!

rel1 Hz

Slow relaxation of atomic polarization:

~ 1 G ~ 0.1 nT

(For FSB agents: this is a joke!)

FM NMOR magnetometry: Phys.Rev.A65, 055403 (2002)

Pumping and probing with FM light

Precision magetometry and atomic EDM measurement using spin-polarized atoms in

a buffer gas at cryogenic temperatures

• Problem: to measure very small B; to measure electron EDM

• Paramagnetic atom magnetometer; He buffer gas at T=4K to increase spin-relaxation time to minutes

Measuring the Kerr effect in LHe and the LANL neutron EDM experiment

• Problem: to measure strong electric fields (50kV/cm) inside a bath of LHe at 300mK.

• Kerr effect: an initially isotropic medium acquires birefringence when electric field is applied, measure this.

241 Birge, midnight, 8/25/03

Light Guides Cells BetweenElectrodes

HV and Ground Electrodes

Beam Entrance Window

HV Variable Capacitor

SQUID Enclosure

Cos Coil

Neutron EDM experiment at LANSCE

Motivation: BEV exp

Lifetimes, branching ratios, new levels, polarizabilities (Ba)

Unusually large polarizabilities

“new” opposite-parity levelsElectron EDM expNoncontact circuit board testing

(100 times; for n<10, only smaller than 2s,2p of H)

Laser spectroscopy for Laser spectroscopy for fundamental symmetry testsfundamental symmetry tests

6s6p 1P1

6s6p 3P0,1,2

Laser Excitation 554.7 nm

Fluorescence~ 435 nm

6s2 1S0

Probed States

Even Parity Odd Parity

559 - 569.5 nm

Laser Excitation

What is the experiment?

A test of the spin statistics theorem (SST) for photons.

What is the SST?

Barium How we do it

Interaction region

Power Build-up Cavity

Oven Housing w/Collimator

1.58"

1.70"

0.28"

0.70"

0.82"

1.22"

1.04"

0.95"

Chamber

Numbers

Experimental Atomic Physics Research in the Budker Group