# Quantum Frequency Conversion of a Quantum Dot Single-Photon Source on a Nanophotonic Chip

## TL;DR

This paper demonstrates the first on-chip quantum frequency conversion of a quantum dot single-photon source on a silicon nanophotonic chip, enabling wavelength tuning and improved source indistinguishability for quantum information applications.

## Contribution

It introduces a scalable, chip-integrated quantum frequency conversion technique for quantum dot single-photon sources, overcoming wavelength inhomogeneity issues.

## Key findings

- Achieved approximately 12% on-chip conversion efficiency.
- Maintained antibunching with g(2)(0) = 0.290 after conversion.
- Effective wavelength tuning across 840-980 nm.

## Abstract

Single self-assembled InAs/GaAs quantum dots are promising bright sources of indistinguishable photons for quantum information science. However, their distribution in emission wavelength, due to inhomogeneous broadening inherent to their growth, has limited the ability to create multiple identical sources. Quantum frequency conversion can overcome this issue, particularly if implemented using scalable chip-integrated technologies. Here, we report the first demonstration of quantum frequency conversion of a quantum dot single-photon source on a silicon nanophotonic chip. Single photons from a quantum dot in a micropillar cavity are shifted in wavelength with an on-chip conversion efficiency of approximately 12 %, limited by the linewidth of the quantum dot photons. The intensity autocorrelation function g(2)(tau) for the frequency-converted light is antibunched with g(2)(0) = 0.290 +/- 0.030, compared to the before-conversion value g(2)(0) = 0.080 +/- 0.003. We demonstrate the suitability of our frequency conversion interface as a resource for quantum dot sources by characterizing its effectiveness across a wide span of input wavelengths (840 nm to 980 nm), and its ability to achieve tunable wavelength shifts difficult to obtain by other approaches.