On-chip indistinguishable photons using III-V nanowire/SiN hybrid integration

TL;DR

This paper reports the on-chip generation of indistinguishable photons from a nanowire quantum dot integrated with a SiN waveguide, achieving high interference visibility and analyzing factors affecting photon coherence.

Contribution

It demonstrates a hybrid integration method for on-chip indistinguishable photon sources using nanowire quantum dots and SiN waveguides, with detailed analysis of photon coherence limitations.

Findings

Achieved 100% two-photon interference visibility with continuous wave excitation.

Observed reduced interference visibility under pulsed excitation due to excitation timing jitter.

Identified spectral diffusion and dephasing as factors limiting photon indistinguishability.

Abstract

We demonstrate on-chip generation of indistinguishable photons based on a nanowire quantum dot. From a growth substrate containing arrays of positioned-controlled single dot nanowires, we select a single nanowire which is placed on a SiN waveguide fabricated on a Si-based chip. Coupling of the quantum dot emission to the SiN waveguide is via the evanescent mode in the tapered nanowire. Post-selected two-photon interference visibilities using continuous wave excitation above-band and into a p-shell of the dot were 100%, consistent with a single photon source having negligible multi-photon emission probability. Visibilities over the entire photon wavepacket, measured using pulsed excitation, were reduced by a factor of 5 when exciting quasi-resonantly and by a factor of 10 for above-band excitation. The role of excitation timing jitter, spectral diffusion and pure dephasing in limiting visibilities over the temporal extent of the photon is investigated using additional measurements of the coherence and linewidth of the emitted photons.