Strong exciton-photon coupling mediated by dephasing in site-controlled InGaAs quantum dots-nanocavities

In coupled solid-state quantum dot (QD)-cavity system, decoherence fundamentally affects coherent controll for quantum communication. Relying on our site-controlled single pyramidal InGaAs/GaAs QD – high Q photonic crystal cavities platform, we systematically investigate the cavity quantum electrodynamics in strong coupling regime mediated by cavity loss and the exciton pure dephasing. The single excitonic emission and cavity mode reveals anti-crossing with vacuum Rabi splitting around 50 µeV and typical averaging of QD-cavity luminescence at near resonance, which indicates strong coupling in our system. More importantly, as cavity loss is larger than pure dephasing rate, we observe linewidth averaging between cavity mode and exciton, which evidences the half-light-half-matter nature. Conversely, when the cavity linewidth is smaller enough and closed to that of exciton, their linewidths exhibit an mutual narrowing at near resonance. It indicates a strong surpression of pure dephasing of excitons owning to its half-photon signature in the strong coupling regime, allowing a less affect from the charge fluctuation and phonon scattering.