What it is
Cavity exciton-polaritons are quasiparticles that form when excitons in a semiconductor quantum well hybridize with the light mode of an optical cavity. Using photon correlation measurements under continuous-wave resonant laser excitation, the authors demonstrate quantum correlations between cavity polaritons in a tunable fiber cavity. The experiments reveal an unexpectedly strong dependence of polariton interactions on the detuning between cavity and exciton. When the polaritons are predominantly exciton-like, the emitted light goes from antibunched, with photons tending to arrive one at a time, to bunched as the laser is tuned across the polariton resonance, in agreement with a simple Kerr-nonlinearity model. When the lower-branch polariton energy is tuned to induce a two-polariton Feshbach resonance with the biexciton mode, the degree of antibunching becomes independent of the laser detuning, which the authors explain by a dissipative blockade mechanism arising from the large broadening of the biexciton. They conclude that the strong polariton blockade regime would be reached by reducing the polariton decay rate by a factor of 10.
Why it matters
Polaritons, part light and part matter, showed quantum correlations in a tunable fiber cavity, their interactions depending unexpectedly strongly on cavity-exciton tuning. At a two-polariton Feshbach resonance with the biexciton, the antibunching of the emitted photons no longer depended on the laser's tuning, which the authors explain by a dissipative blockade, and they estimate that cutting the polariton decay rate by a factor of 10 would reach the strong blockade regime.
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Filed underStrong Light-Matter Interactions, Semiconductor Quantum Structures and Devices, Quantum optics and atomic interactions
