7 research outputs found
On the possibility of a terahertz light emitting diode based on a dressed quantum well
We consider theoretically the realization of a tunable terahertz light
emitting diode from a quantum well with dressed electrons placed in a highly
doped p-n junction. In the considered system the strong resonant dressing field
forms dynamic Stark gaps in the valence and conduction bands and the electric
field inside the p-n junction makes the QW asymmetric. It is shown that the
electrons transiting through the light induced Stark gaps in the conduction
band emit photons with energy directly proportional to the dressing field. This
scheme is tunable, compact, and shows a fair efficiency.Comment: 6 pages, 5 figure
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 excitonâpolariton 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
Room-temperature superfluidity in a polariton condensate
Superfluidityâthe suppression of scattering in a quantum fluid at velocities below a critical valueâis one of the most striking manifestations of the collective behaviour typical of BoseâEinstein condensates1. This phenomenon, akin to superconductivity in metals, has until now been observed only at prohibitively low cryogenic temperatures. For atoms, this limit is imposed by the small thermal de Broglie wavelength, which is inversely related to the particle mass. Even in the case of ultralight quasiparticles such as exciton-polaritons, superfluidity has been demonstrated only at liquid helium temperatures2. In this case, the limit is not imposed by the mass, but instead by the small binding energy of WannierâMott excitons, which sets the upper temperature limit. Here we demonstrate a transition from supersonic to superfluid flow in a polariton condensate under ambient conditions. This is achieved by using an organic microcavity supporting stable Frenkel exciton-polaritons at room temperature. This result paves the way not only for tabletop studies of quantum hydrodynamics, but also for room-temperature polariton devices that can be robustly protected from scattering