Quantum technology – Qubits and quantum emitters – Single and indistinguishable photon sources based on semiconductor quantum dots


Valia Voliotis, Paloa Atkinson in collaboration with Richard Hostein (My Cryo Firm Company)

It is now well established that quantum dots, two-level solid-state systems, are efficient and bright sources of single photons. Through photon correlation experiments we have measured the generation of non-classical states of light [1]. The emitted photons are indistinguishable and the degree of indistinguishability depends on the different decoherence mechanisms at work in the solid system. We have shown that the degree of indistinguishability of the emitted photons is higher than 0.8, measured by photon coalescence experiments at the resonance thanks to the implementation of a Hong-Ou-Mandel experiment. The HOM experiments as a function of temperature, show that the degree of indistinguishability is preserved up to a temperature of the order of 10 K and then drops rapidly. We have shown that the interaction with the acoustic phonon bath is the dominant mechanism of dephasing and constitutes an intrinsic limitation to the coherence properties of the solid system [2].

CaptionImage of a one-dimensional waveguide in which is located the plane of quantum dots inserted in Bragg mirrors (image C2N). The dots are represented schematically by yellow blocks. The resonant excitation is done along the guide while the emitted photons are collected by the surface. In the center of the figure is represented a histogram of the coincidences of the photons detected by two photodiodes placed on both sides of a beamsplitter. The coincidence deep at zero delay proves that the photons are emitted one by one. The degree of indistinguishability of single photons measured by two-photon interference experiments is more than 80% at low temperature and limited by the interaction with acoustic phonons when the temperature is increased.


[1] Léonard Monniello, Antoine Reigue, Richard Hostein, Aristide Lemaitre, Anthony Martinez, et al.. Indistinguishable single photons generated by a quantum dot under resonant excitation observable without postselection. Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2014, 90 (4), pp. 041303(R). ⟨10.1103/PhysRevB.90.041303⟩. ⟨hal-01229151⟩
[2] A. Reigue, F. Lux, L. Monniello, M. Bernard, F. Margaillan, A. Lemaître, J.Iles-Smith, J. Mork, R. Hostein, and V. Voliotis, Probing exciton-photon interaction by two-photon interferences in a resonantly driven quantum dot, Phys. Rev. Lett. 118, 233602 (2017) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.233602