Deterministic assembly of a charged quantum dot-micropillar cavity device

Developing future quantum communication may rely on the ability to engineer cavity-mediated interactions between photons and solid-state artificial atoms, in a deterministic way. Here, we report a set of technological and experimental developments for the deterministic coupling between the optical mode of a micropillar cavity and a quantum dot trion transition. We first identify a charged transition through in-plane magnetic field spectroscopy, and then tune the optical cavity mode to its energy via in-situ lithography. In addition, we design an asymmetric tunneling barrier to allow the optical trapping of the charge, assisted by a quasi-resonant pumping scheme, in order to control its occupation probability. We evaluate the generation of a positively-charged quantum dot through second order auto-correlation measurements of its resonance fluorescence, and the quality of light-matter interaction for these spin-photon interfaces is assessed by measuring the performance of the device as a single-photon source.Comment: 9 pages, 7 figure

Photoluminescence probing of non-radiative channels in hydrogenated In(Ga)As/GaAs quantum dots

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Measuring Topological Invariants in a Polaritonic Analog of Graphene

Suppl. Mat. added; improved data/error analysisInternational audienceTopological materials rely on engineering global properties of their bulk energy bands called topological invariants. These invariants, usually defined over the entire Brillouin zone, are related to the existence of protected edge states. However, for an important class of Hamiltonians corresponding to 2D lattices with time-reversal and chiral symmetry (e.g., graphene), the existence of edge states is linked to invariants that are not defined over the full 2D Brillouin zone, but on reduced 1D subspaces. Here, we demonstrate a novel scheme based on a combined real- and momentum-space measurement to directly access these 1D topological invariants in lattices of semiconductor microcavities confining exciton polaritons. We extract these invariants in arrays emulating the physics of regular and critically compressed graphene where Dirac cones have merged. Our scheme provides a direct evidence of the bulk-edge correspondence in these systems and opens the door to the exploration of more complex topological effects, e.g., involving disorder and interactions

Polariton-polariton Interactions and Stimulated Emission in Semiconductor Microcavities

Recent work on polariton-polariton scattering in semiconductor microcavities under continuous wave excitation conditions is reviewed. For weak non-resonant laser excitation, a marked bottleneck in the polariton distribution is observed, but which is suppressed by polariton-polariton scattering as the laser intensity is increased. However, the high excitation conditions necessary to observe stimulated emission lead to loss of strong coupling and conventional lasing in the weak coupling regime, By contrast for resonant excitation, polaritons are created directly in the polariton trap formed by the microcavity dispersion curve. Stimulated scattering of the bosonic quasi-particles occurs to the emitting state at the centre of the Brillouin zone, and to a companion state at high wavevector. The stimulation phenomena lead to condensation of the bosonic quasi-particles to two specific regions of k-space, and to the formation of a new state with macroscopic coherence. The prospects to achieve a polariton laser under conditions of non-resonant excitation are discussed