Ultrafast control of cavity quantum electrodynamics beyond the radiative lifetime

Cavity quantum electrodynamics (CQED) represents one of the most fascinating systems for the study of quantum physics. Solid-state CQED systems, for example based on semiconductor nanocavities coupled to single quantum dots (QDs), are particularly interesting for their potential scalability and integration. However, the progress in solid-state CQED has so far been hampered by the very limited degree of control, due to the ultrafast picosecond time scales and subwavelength spatial scales, which make the control of the QD-photon interaction in real time a formidable challenge. Recently, we have proposed and demonstrated an ultrafast, non-local control scheme based on the coupling of a control cavity to a target cavity containing QD emitters. By injecting free carriers into the control cavity, the electric field distribution in the coupled-cavity system can be modified, resulting in the real-time shaping of vacuum field at the target cavity without directly perturbing the emitter's coherent evolution. The QD-cavity interaction rate and the spontaneous emission rate are manipulated on a timescale of ~200 ps, well below the radiative lifetime. This opens the way to the real-time control of solid-state CQED and towards novel forms of nanophotonic devices.