Nonlinear Quantum Optics with Trion Polaritons in 2D Monolayers: Conventional and Unconventional Photon Blockade.

We study a 2D system of trion polaritons at the quantum level and demonstrate that for monolayer semiconductors they can exhibit a strongly nonlinear optical response. The effect is due to the composite nature of trion-based excitations resulting in their nontrivial quantum statistical properties, and enhanced phase space filling effects. We present the full quantum theory to describe the statistics of trion polaritons, and demonstrate that the associated nonlinearity persists at the level of few quanta, where two qualitatively different regimes of photon antibunching are present for weak and strong single photon-trion coupling. We find that single photon emission from trion polaritons becomes experimentally feasible in state-of-the-art transition metal dichalcogenide setups. This can foster the development of quantum polaritonics using 2D monolayers as a material platform.

Highly nonlinear trion-polaritons in a monolayer semiconductor.

Highly nonlinear optical materials with strong effective photon-photon interactions are required for ultrafast and quantum optical signal processing circuitry. Here we report strong Kerr-like nonlinearities by employing efficient optical transitions of charged excitons (trions) observed in semiconducting transition metal dichalcogenides (TMDCs). By hybridising trions in monolayer MoSe2 at low electron densities with a microcavity mode, we realise trion-polaritons exhibiting significant energy shifts at small photon fluxes due to phase space filling. We find the ratio of trion- to neutral exciton-polariton interaction strength is in the range from 10 to 100 in TMDC materials and that trion-polariton nonlinearity is comparable to that in other polariton systems. The results are in good agreement with a theory accounting for the composite nature of excitons and trions and deviation of their statistics from that of ideal bosons and fermions. Our findings open a way to scalable quantum optics applications with TMDCs.

Floquet control of dipolaritons in quantum wells.

We developed the theory of dipolaritons in semiconductor quantum wells irradiated by an off-resonant electromagnetic wave (dressing field). Solving the Floquet problem for the dressed dipolaritons, we demonstrated that the field drastically modifies all dipolaritonic properties. In particular, the dressing field strongly affects the terahertz emission from the considered system. The described effect paves the way for optical control of prospective dipolariton-based terahertz devices.

Optomechanics with cavity polaritons: dissipative coupling and unconventional bistability.

We study a hybrid system formed from an optomechanical resonator and a cavity mode strongly coupled to an excitonic transition inside a quantum well. We show that due to the mixing of cavity photon and exciton states, the emergent quasiparticles-polaritons-possess coupling to the mechanical mode of both a dispersive and dissipative nature. We calculate the occupancies of polariton modes and reveal bistable behavior, which deviates from conventional Kerr nonlinearity or dispersive coupling cases due to the dissipative coupling. The described system serves as a good candidate for future polaritonic devices.

Superradiant terahertz emission by dipolaritons.

Dipolaritons are mixed light-matter quasiparticles formed in double quantum wells embedded in microcavities. Because of resonant coupling between direct and indirect excitons via electronic tunneling, dipolaritons possess large dipole moments. Resonant excitation of the cavity mode by a short pulse of light induces oscillations of the indirect exciton density with a characteristic frequency of Rabi flopping. This results in oscillations of a classical Hertz dipole array which generate supperradiant emission on a terahertz (THz) frequency. The resulting THz signal may be enhanced using the supplementary THz cavity in the weak coupling regime.