High visibility time-energy entangled photons from a silicon nanophotonic chip

TL;DR

This paper demonstrates a silicon nanophotonic chip that produces highly entangled photon pairs with record raw entanglement quality and high generation rates, advancing integrated quantum photonics.

Contribution

It introduces a high-Q silicon microdisk resonator with cavity-enhanced SFWM for efficient, high-quality time-energy entangled photon pair generation on a chip.

Findings

Achieved nearly perfect coincidence visibility of 96.6% without background subtraction.

Generated photon pairs at a rate of approximately 440,000 pairs per second.

Demonstrated the highest raw degree of time-energy entanglement from a chip-scale source.

Abstract

Advances in quantum photonics have shown that chip-scale quantum devices are translating from the realm of basic research to applied technologies. Recent developments in integrated photonic circuits and single photon detectors indicate that the bottleneck for fidelity in quantum photonic processes will ultimately lie with the photon sources. We present and demonstrate a silicon nanophotonic chip capable of emitting telecommunication band photon pairs that exhibit the highest raw degree of time-energy entanglement from a micro/nanoscale source, to date. Biphotons are generated through cavity-enhanced spontaneous four-wave mixing (SFWM) in a high-Q silicon microdisk resonator, wherein the nature of the triply-resonant generation process leads to a dramatic Purcell enhancement, resulting in highly efficient pair creation rates as well as extreme suppression of the photon noise background. The combination of the excellent photon source and a new phase locking technique, allow for the observation of a nearly perfect coincidence visibility of (96.6 $\pm$ 1.1)$\%$, without any background subtraction, at a large pair generation rate of (4.40 $\pm$ 0.07) $\times$ 10$^5$ pairs/s.