# Tunable quantum beat of single photons enabled by nonlinear nanophotonics

## TL;DR

This paper demonstrates the creation of tunable quantum interference between single photons using nonlinear nanophotonic resonators, enabling precise control over quantum states for advanced quantum information applications.

## Contribution

It introduces a novel method combining nonlinear nanophotonics and four-wave mixing to achieve tunable quantum interference of single photons.

## Key findings

- Successful frequency shifting of single photons without degrading their quantum statistics.
- Demonstration of tunable quantum interference with adjustable frequency differences.
- Potential for scalable quantum information processing using integrated nanophotonic devices.

## Abstract

We demonstrate the tunable quantum beat of single photons through the co-development of core nonlinear nanophotonic technologies for frequency-domain manipulation of quantum states in a common physical platform. Spontaneous four-wave mixing in a nonlinear resonator is used to produce non-degenerate, quantum-correlated photon pairs. One photon from each pair is then frequency shifted, without degradation of photon statistics, using four-wave mixing Bragg scattering in a second nonlinear resonator. Fine tuning of the applied frequency shift enables tunable quantum interference of the two photons as they are impinged on a beamsplitter, with an oscillating signature that depends on their frequency difference. Our work showcases the potential of nonlinear nanophotonic devices as a valuable resource for photonic quantum information science.