Iacopo Carusotto

Quantum vacuum properties of the intersubband cavity polariton field

We present a quantum description of a planar microcavity photon mode strongly coupled to a semiconductor intersubband transition in presence of a two-dimensional electron gas. We show that, in this kind of system, the vacuum Rabi frequency

Polariton Superfluids Reveal Quantum Hydrodynamic Solitons

\Omega_R

Excitations in a nonequilibrium Bose-Einstein condensate of exciton polaritons.

can be a significant fraction of the intersubband transition frequency

Direct Observation of Dirac Cones and a Flatband in a Honeycomb Lattice for Polaritons

\omega_{12}

Probing microcavity polariton superfluidity through resonant Rayleigh scattering

. This regime of ultra-strong light-matter coupling is enhanced for long wavelength transitions, because for a given doping density, effective mass and number of quantum wells, the ratio

Quantum Vacuum Radiation Spectra from a Semiconductor Microcavity with a Time-Modulated Vacuum Rabi Frequency

\Omega_R/\omega_{12}

Fermionized Photons in an Array of Driven Dissipative Nonlinear Cavities

increases as the square root of the intersubband emission wavelength. We characterize the quantum properties of the ground state (a two-mode squeezed vacuum), which can be tuned {\it in-situ} by changing the value of

Input-output theory of cavities in the ultrastrong coupling regime: The case of time-independent cavity parameters

\Omega_R

Numerical observation of Hawking radiation from acoustic black holes in atomic Bose-Einstein condensates

, e.g., through an electrostatic gate. We finally point out how the tunability of the polariton quantum vacuum can be exploited to generate correlated photon pairs out of the vacuum via quantum electrodynamics phenomena reminiscent of the dynamic Casimir effect.

Fractional quantum Hall states of photons in an array of dissipative coupled cavities

A condensed-matter system is used to study superfluid dynamics. A quantum fluid passing an obstacle behaves differently from a classical one. When the flow is slow enough, the quantum gas enters a superfluid regime, and neither whirlpools nor waves form around the obstacle. For higher flow velocities, it has been predicted that the perturbation induced by the defect gives rise to the turbulent emission of quantized vortices and to the nucleation of solitons. Using an interacting Bose gas of exciton-polaritons in a semiconductor microcavity, we report the transition from superfluidity to the hydrodynamic formation of oblique dark solitons and vortex streets in the wake of a potential barrier. The direct observation of these topological excitations provides key information on the mechanisms of superflow and shows the potential of polariton condensates for quantum turbulence studies.