High Purcell Enhancement in Quantum-Dot Hybrid Circular Bragg Grating Cavities for GHz Clock Rate Generation of Indistinguishable Photons

We present Purcell-enhanced (FP > 25) semiconductor InAs quantum dot decay times of T1 < 30 ps, enabled by deterministic hybrid circular Bragg gratings (hCBGs). We investigate the benefits of these short T1-times on the two-photon indistinguishability for quasi-resonant and strictly resonant excitation and observe visibilities of ≥96% at 12.5 ns time delay of consecutively emitted photons. The strongly Purcell-enhanced decay times enable a high degree of indistinguishability for elevated temperatures of up to 30 K and, moreover, allow for excitation of up to 1.28 GHz repetition rate. Our work highlights the prospects of highly Purcell-enhanced solid-state quantum emitters for applications in quantum information and technologies operating at GHz clock rates.