ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD

Godefroy Leménager1, F Pisanello1,2, L Martiradonna3, P Spinicelli1, A Fiore2, J-P Hermier4, L Manna5, R Cingolani2,3, E Giacobino1, M De Vittorio2,3 and A

Bramati1

1 Laboratoire Kastler Brossel, Paris, France.

2 National Nanotechnology Laboratory, Lecce, Italy.3 Istituto Italiano di Tecnologia, Arnesano (Lecce).4 Groupe d'étude de la Matière Condensée, Versailles, France.5 Istituto Italiano di Tecnologia, Genova.

[email protected]

ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD.

PLMCN 10, 12/16 avril 2010 Cuernavaca

G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD.


Why single photon sources?

Quantum Information

Quantum computation

Polarized single photon sources are usually needed

Several keys distribution algorithms are based on photon polarization, such as BB84 or B92

Bennett and Brassard, Int. Conf. on Computers, Systems and Signal Processing, India, December 10–12, 1984, p. 175.

Alice Bob

Quantum error corrections

Quantum cryptography



Why single emitter florescence for single photon sources?

Laser Attenuated laser

Pulsed Laser

Single emitter florescence

Ec

Ev

Ec-Evhν > Ec-Ev



Epitaxial or colloidal artificial atoms?

• Higher distance among allowed energy states in conduction and valence bands: intense emission also at room temperature

• Broad tunable emission range• Low costs and versatile synthesis

procedures

BlinkingNot collimated and not polarized emission

ColloidalSPSs [2]

P. Michler et al., Nature 406, 968 (2000).

EpitaxialEpitaxialgrowth SPSsgrowth SPSs

A. Tribu et al., Nano Lett. 8, 4326 (2008).Y. Arakawa et al., Nat. Mat. 5, 887 (2006).

Stranski-Krastanow growth Metal-Organic Chemical Vapor

Deposition (MOCVD) /Molecular Beam Epitaxy (MBE)

efficient electrical injection by p-n doping of the surrounding heterostructure

Expensive techniques requiredRoom-temperature emission from single QD difficult to be achieved due to phonons energy comparable with allowed energy levels distance



Linear Dipole Moment

Colloidal Nanocrystals Engineering

B. Malher et al., Nature Mat. 7, 659 (2008).

CdS

CdSe

Blinking suppression

CdSe

CdS

Shell

Core

High quantum yieldIncreasing spontaneous emission rate

A. Qualtieri et al., New J. Phys 11, 033025 (2009).



Antonio Qualtieri et al 2009 New J. Phys. 11 033025

Nanocristals

in the cavity

Nanocristals

not in the cavity

Increasing spontaneous emission rate



Linear Dipole Moment

Colloidal Nanocrystals Engineering

B. Malher et al., Nature Mat. 7, 659 (2008).

CdS

CdSe

Blinking suppression

CdSe

CdS

Shell

Core

High quantum yieldIncreasing spontaneous emission rate

A. Qualtieri et al., New J. Phys 11, 033025 (2009).

HRTEM Images



Seeded growth colloidal dot in a rod

200nm

Carbone et al., Nano Letters 7, 2942 (2007).



How to characterize a polarized single photon source?

Picoseconds pulsed laser

=404nm

1. Coincidences histogram

2. Delay between photons and laser pulse

Acquisition card

λ/4 plate

pin-holeλ/2 plate

Polarizer

Low density dots-in-rod

sample

APD1

APD2

Beam Splitter 50%-50%

Polarized Hanbury Brown and Twiss interferometer

/2 plateEmission = 595nm



Luminescence topography

15 000 [photons/s]

0

y

x0 5um

0

5um



Single photon source ?

F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010)F. Pisanello et al., Superlattices and Microstructures 47, 165 (2009)



Photoluminescence intensity

0 5 10 15 20



θ=0°

Photoluminescence intensity

θ=90°

0 5 10 15 20



Properties of the polarized emission

F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010)



Focus Dipole like EmitterOmnidirectional Emitter

X. Brokman Phd Thesis UPMC (2004)

Orientation of the Dot in Rod



Focalised pictureDefocalised picture









Device



Device

E

E

L Carbone et al. Nano Lett., 2007, 7 (10), pp 2942–2950



Conclusion The polarization properties of a single, isolated dot in

rod are presented

We show that a single dot in a rod is a polarized single photon source

The degree of polarization of the emission around 80%


We show the possibility to identify the orientation of a single Dot-in-Rod

We propose a strategy to implement the sender site in a device



Work in progress

Implement the device proposed

Analysis of different lengths of cores and shells

Spectrum measurements

Coherence time measurements



Thanks to :• Antonio Qualtieri

• Riccardo Messina

• Gianmichele Epifani

• Dr. Giuseppe Patera

• Dr. Giovanni Morello

• Gianvito Caputo

• Dr. Alessandro Massaro

• Dr. Vittorianna Tasco

• Dr. Maria Teresa Todaro



Thank you for your attention

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ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD