Two-photon interference from a quantum emitter in hexagonal boron nitride

TL;DR

This study demonstrates two-photon interference from a quantum emitter in hexagonal boron nitride, revealing partial photon indistinguishability and estimating the emitter's dephasing time, advancing integrated quantum photonics with 2D materials.

Contribution

It provides the first measurement of two-photon interference in hBN quantum emitters, quantifies photon indistinguishability, and estimates the emitter's dephasing time, highlighting potential for photonic integration.

Findings

Photon indistinguishability of 0.44 (uncorrected) and 0.56 (corrected)

Dephasing time estimated at ~1.5 ns

Potential for >90% visibility with Purcell enhancement

Abstract

Recently discovered quantum emitters in two-dimensional (2D) materials have opened new perspectives of integrated photonic devices for quantum information. Most of these applications require the emitted photons to be indistinguishable, which has remained elusive in 2D materials. Here, we investigate two-photon interference of a quantum emitter generated in hexagonal boron nitride (hBN) using an electron beam. We measure the correlations of zero-phonon-line photons in a Hong-Ou-Mandel (HOM) interferometer under non-resonant excitation. We find that the emitted photons exhibit a partial indistinguishability of $0.44 \pm 0.11$ in a 3 ns time window, which corresponds to a corrected value of $0.56 \pm 0.11$ after accounting for imperfect emitter purity. The dependence of the HOM visibility on the width of the post-selection time window allows us to estimate the dephasing time of the emitter to be $\sim 1.5$ ns, about half the limit set by spontaneous emission. A visibility above 90 % is under reach using Purcell effect with up-to-date 2D material photonics.