LKB - Atom chips group

Solid-state cavity QED

Light matter interaction takes a prominent part in quantum physics since its beginning. This particular experiment aims for the interaction between elementary excitations of semi-conductor heterostructures (quantum dots and wells excitons) and one fiber Fabry Pérot cavity mode and thus it works at the intersection of quantum optics and mesoscopic condensed matter physics.

Microcavities open many new possibilities for investigations of quantum dots. The flexibility of the FFP microcavity can be exploited, for example, to increase the cavity quality factor by lengthening the latter. In integrated solid cavities, the lifetime of the photons is usually the limiting factor for the lifetime of polaritons. By increasing the latter, the FFP microcavities therefore allow a priori to approach the thermodynamic equilibrium properties of the system. The strong nonlinearity observed in the dependence of the photoluminescence signal with excitation power also corresponds fairly well to the phase diagram predicted by the Dicke model at thermodynamic equilibrium.

The lateral confinement is also ideal for the observation of effects due to interactions between polaritons. For a polariton system confined in a cavity with a large quality factor, a quantum polariton blockade has even been predicted. In this context, the FFP microcavities are comparable to micro-pillars, where the quality factor is strongly reduced for diameters less than 3 µm, due to losses at the edges of the structure.

We also collaborate with Laboratoire Pierre Aigrain on carbon nanotube CQED.