Laser oscillation in a strongly coupled single-quantum-dot-nanocavity system

The strong coupling of photons and matter ¹ in semiconductor nanocavities has been a test bed for cavity quantum electrodynamics ^2,3 (QED). Vacuum Rabi oscillation ^4-8 -the coherent exchange of a single quantum between a single quantum dot (SQD) and an optical cavityand highly efficient cavity-QED lasers ^9-19 have both been reported. The coexistence of vacuum Rabi oscillation and laser oscillation seems to be contradictory, but it has recently been predicted theoretically that the strong-coupling effect could be sustained in laser oscillation ²⁰ . Here, we demonstrate the onset of lasing in the strong-coupling regime in an SQD-cavity system. A high-quality semiconductor optical nanocavity and strong SQD-field coupling enabled the onset of lasing while maintaining the fragile coherent exchange of quanta.