Quantum dots for single and entangled photon emitters

D. Bimberg; E. Stock; A. Lochmann; A. Schliwa; W. Unrau; M. Münnix; S. Rodt; A. I. Toropov; A. Bakarov; A. K. Kalagin; V. A. Haisler

doi:10.1117/12.846782

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24 February 2010 Quantum dots for single and entangled photon emitters

D. Bimberg, E. Stock, A. Lochmann, A. Schliwa, W. Unrau, M. Münnix, S. Rodt, A. I. Toropov, A. Bakarov, A. K. Kalagin, V. A. Haisler

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Proceedings Volume 7610, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VII; 76100G (2010) https://doi.org/10.1117/12.846782
Event: SPIE OPTO, 2010, San Francisco, California, United States

Abstract

Efficient generation of polarized single or entangled photons is a crucial requirement for the implementation of quantum key distribution (QKD) systems. Self-organized semiconductor quantum dots (QDs) are capable of emitting one polarized photon or an entangled photon pair at a time using appropriate electrical current injection. We realized highly efficient single photon sources (SPS) based on well established semiconductor technology: In a pin structure a single electron and a single hole are funneled into a single InAs quantum dot using a submicron AlOx current aperture. Efficient radiative recombination leads to emission of single polarized photons with an all-time record purity of the spectrum. Non-classicality of the emitted light without using additional spectral filtering is demonstrated. Out-coupling efficiency and emission rate are increased by embedding the SPS into a micro-cavity of Q = 140. The design of the micro-cavity is based on detailed modeling to optimize its performance. The resulting resonant single-QD diode generates single polarized photons at a repetition rate of 1 GHz exhibiting a second order correlation function of g⁽²⁾(0) = 0. Eventually, QDs grown on (111) oriented substrate are proposed as source of entangled photon pairs. Intrinsic symmetry-lowering effects leading to the splitting of the exciton bright states are shown to be absent for this substrate orientation. As a result the XX → X → 0 recombination cascade of a QD can be used for the generation of entangled photons without further tuning of the finestructure splitting via QD size and/or shape. We present first micro-photoluminescence studies on QDs grown on (111) GaAs, demonstrating a fine structure splitting less than the spectral resolution of our set-up.

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D. Bimberg, E. Stock, A. Lochmann, A. Schliwa, W. Unrau, M. Münnix, S. Rodt, A. I. Toropov, A. Bakarov, A. K. Kalagin, and V. A. Haisler "Quantum dots for single and entangled photon emitters", Proc. SPIE 7610, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VII, 76100G (24 February 2010); https://doi.org/10.1117/12.846782

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