Highly-Indistinguishable Single-Photons at 1550 nm from a Two-photon Resonantly Excited Purcell-enhanced Quantum Dot

TL;DR

This paper reports a highly efficient, cavity-enhanced quantum dot single-photon source at 1550 nm with record low decay time, high purity, and near-theoretical two-photon interference visibility, advancing quantum communication technologies.

Contribution

It introduces a novel cavity-enhanced quantum dot source with record-low biexciton decay time and demonstrates stimulated two-photon excitation with improved interference visibility.

Findings

Record-low biexciton decay time of 67.4 ps.

High multiphoton suppression with g^{(2)} values below 0.01.

Two-photon interference visibility exceeding 90%.

Abstract

In this work we present a cavity-enhanced InAs/$\mathrm{In_{0.53}Al_{0.23}Ga_{0.24}As}$ quantum dot (QD) single-photon source in the telecom C-band with a record-low biexciton emitter decay time of \SI{67.4(2)}{ps} under resonant two-photon excitation (TPE). We observe strong multiphoton suppression associated with $g^{(2)}_\mathrm{X}(0) = 0.006(1)$ and $g^{(2)}_\mathrm{XX}(0) = 0.007(1)$ for the exciton (X) and biexciton (XX) emission, respectively. Due to a asymmetric Purcell enhancement of the XX-X cascade, the two-photon interference (TPI) visibility of XX photons under $\pi$-pulse excitation of $V_{\rm{TPI}} = 90(3)\%$ reaches the theoretical limit and clearly exceeds the $\sim60\%$ expected for standard XX-X cascades without photonic engineering. Furthermore, adding a second timed laser pulse coinciding with XX emission energy, we demonstrate stimulated TPE in the telecom C-Band. The result is an improved TPI visibility of the X photons of $V_{\rm{TPI}}=0.69(3)$ compared to TPE with $V_{\rm{TPI}}=0.61(4)$, with both being reduced compared to the theoretical values due to present dephasing effects. The advances presented in this work hold important promises for the implementation of advanced schemes of quantum communication using deterministic quantum light sources.