Claudéric Ouellet-Plamondon

Semiconductor quantum wells and quantum dots have demonstrated over the years to be ideal systems for studying light–matter interaction.  The key advantage of these platforms rely on the possibility to control their emission properties by embedding the emitter in a photonic structure. On the one hand, placing quantum wells inside a microcavity allows to reach the strong coupling regime and the study of 2D polariton quantum fluids. On the other hand, single QDs inside nanophotonic devices is an essential building block for single-photon generation and quantum network architecture.

In the first part of my presentation, I will discuss how we can engineer planar microcavity structures into more complex optical lattices, opening the way toward spin Hamiltonian simulations with polaritons. Before studying coherent control in polariton lattices, we investigate the optical response of a single trap in the regime of polariton bistability. We provide evidence of a dephasing channel induced by an incoherent exciton reservoir, on top of the usual exciton-exciton interaction driving the non-linearity of the system. In a second experiment, we used two coupled optical traps to study the emission statistics of a polariton Josephson junction. The experiment shows that quadrature squeezing occurs periodically, as the polariton population oscillates between the two optical traps. 

 In the second part of my talk I will discuss recent development on efficient single-photon source based on quantum dots embedded in nanophotonic devices. Optimization of outcoupler has greatly improved the collection efficiency of our devices up to 60% with up to 1 MHz detected single photon rate. Such a bright source was used to demonstrate efficient demultiplexing of single photons.  On a similar device, we are investigating limitations to quantum efficiency of QD single-photon sources due to blinking. Second order correlation of single photons emitted under resonant excitation allows the observation of slow and fast photon bunching occurring on top of the usual Rabi oscillation. The later phenomenon is attributed to a fast dark state in the system that affects both the emission statistics of the source and the coherence of the emitted photons.