Overcoming phonon-induced decoherence in single-photon sources with cavity quantum electrodynamics

Solid-state emitters are excellent candidates for developing integrated sources of single photons. Yet, phonons degrade the photon indistinguishability both through pure dephasing and through phonon-assisted emission. Here, we study the indistinguishability of photons emitted by a semiconductor quantum dot in a microcavity as a function of temperature. We use electrically tunable devices to keep the exciton transition resonant to the cavity mode at all temperatures. We show that a strong Purcell effect can overcome simultaneously both phonon-induced sources of decoherence: strong acceleration of the spontaneous emission overcomes the effect of pure dephasing, while efficiently redirecting the phonon sidebands into the zero-phonon line. Such effects in a high quality factor cavity are shown to lift the need for spectral postselection and to increase the temperature range for the generation of indistinguishable photons.