Quantum-dot nanolasers — From control of spontaneous emission to superradiance

CONTROL of spontaneous emission itself is amongst the most intriguing and, at the same time, application-defining aspects of cavity-quantum electrodynamics (QED). In tailored dielectric structures, such as photonic crystal or micropillar cavities, light is confined to the cubic wavelength. Gain material embedded in such tiny mode volume interacts much more strongly with the electromagnetic field. The resulting enhancement of the spontaneous emission rate, in combination with small losses, put the realization of lasing with a single quantum-emitter in the solidstate within close reach. At the same time, a large ratio of coupling strength to dissipation rates is the requirement for strong light-matter coupling, the ultimate demonstration of which are vacuum Rabi oscillations - the temporal reflection of a coherent energy exchange between a single photon and a single electronic excitation [1].