Low-noise Optomechanical Single Phonon-photon Conversion for Quantum Networks

TL;DR

This paper demonstrates low-noise, high-purity single phonon-photon conversion in optomechanical crystals, enabling scalable quantum networks with long coherence times and minimal thermal noise.

Contribution

It introduces a quasi-two-dimensional optomechanical crystal design that reduces thermal noise, enabling efficient single phonon-photon conversion and high-quality single photon generation.

Findings

Verified low thermal noise and high purity of single photons.

Achieved Hong-Ou-Mandel interference with visibility 0.52.

Demonstrated narrow bandwidths of 10 MHz for generated photons.

Abstract

Nano-structured optomechanical crystals (OMC) form an interface between mechanical modes with long coherence times and telecom optical photons, ideal for long-distance distribution of quantum information. However, the implementation of scalable quantum networks based on OMCs has been inhibited by thermal mechanical noise. Here, we overcome this limitation using a quasi-two-dimensional OMC and generate single photons via single phonon-photon conversion. In this work, we verify the low thermal noise and high purity of the generated single photons through a Hanbury Brown-Twiss experiment with $g^{(2)}(0)=0.35^{+0.10}_{-0.08}$. We perform Hong-Ou-Mandel interference of the emitted photons showcasing the indistinguishability and coherence with visibility $V=0.52 \pm 0.15$ after 1.43 km fiber delay. Lastly, we use two-photon interference to measure the temporal wavepackets of optomechanically generated single photons demonstrating narrow bandwidths as low as 10 MHz. Our results pave the way for multinode quantum networks of mechanical oscillators and hybrid entanglement generation between mechanical oscillators and telecom quantum emitters.