1. Godefroy Leménager 1, F Pisanello 1,2, L Martiradonna 3, P Spinicelli 1, A Fiore 2, J-P Hermier 4, L Manna 5, R Cingolani 2,3, E Giacobino 1, M De Vittorio 2,3 and A Bramati 1 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. lemenager@spectro.jussieu.fr ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca

2. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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. Quantum error corrections Quantum cryptography

3. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Why single emitter florescence for single photon sources? LaserAttenuated laser Pulsed Laser Single emitter florescence Ec-Ev hν > Ec-Ev

4. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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 Blinking Not collimated and not polarized emission Colloidal SPSs [2] P. Michler et al., Nature 406, 968 (2000).Epitaxial growth 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 required Room-temperature emission from single QD difficult to be achieved due to phonons energy comparable with allowed energy levels distance

5. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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 yield Increasing spontaneous emission rate A. Qualtieri et al., New J. Phys 11, 033025 (2009).

6. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Antonio Qualtieri et al 2009 New J. Phys. 11 033025 Nanocristals in the cavity Nanocristals not in the cavity Increasing spontaneous emission rate

7. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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 yield Increasing spontaneous emission rate A. Qualtieri et al., New J. Phys 11, 033025 (2009).

8. HRTEM Images G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Seeded growth colloidal dot in a rod Carbone et al., Nano Letters 7, 2942 (2007).

9. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca How to characterize a polarized single photon source? Picoseconds pulsed laser =404nm 1.Coincidences histogram 2.Delay between photons and laser pulse Acquisition card Polarized Hanbury Brown and Twiss interferometer /2 plate Emission  = 595nm

10. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Luminescence topography 15 000 [photons/s] 0 y x 0 5um 0

11. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Single photon source ? F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010) F. Pisanello et al., Superlattices and Microstructures 47, 165 (2009)

12. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Photoluminescence intensity 05101520

13. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca θ=0° Photoluminescence intensity θ=90° 05101520

14. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Properties of the polarized emission F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010)

15. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Focus Dipole like EmitterOmnidirectional Emitter X. Brokman Phd Thesis UPMC (2004) Orientation of the Dot in Rod

16. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Focalised picture Defocalised picture Orientation of the Dot in Rod F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010)

17. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Orientation of the Dot in Rod F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010)

18. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Device

19. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Device E E L Carbone et al. Nano Lett., 2007, 7 (10), pp 2942–2950

20. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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% F. Pisanello et al., Appl. Phys. Let. 96, 033101 (2010) 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

21. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Work in progress Implement the device proposed Analysis of different lengths of cores and shells Spectrum measurements Coherence time measurements

22. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca 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

23. G. Leménager : ROOM TEMPERATURE POLARIZED SINGLE PHOTON SOURCE WITH A COLLOIDAL DOT IN ROD. PLMCN 10, 12/16 avril 2010 Cuernavaca Thank you for your attention