Photon Conversion and Interaction on Chip

TL;DR

This paper demonstrates ultra-efficient on-chip sum-frequency generation using a lithium niobate microring, achieving record conversion efficiency and low noise, advancing quantum nonlinear optics at the single-photon level.

Contribution

The work introduces a fully optimized lithium niobate microring achieving record quantum efficiency and low noise for single-photon conversion, surpassing previous benchmarks.

Findings

Quantum efficiency of 65% at low pump power

Conversion probability of 10^-5 per single pump photon

Photon-photon coupling strength of 9.1 MHz

Abstract

The conversion and interaction between quantum signals at a single-photon level are essential for scalable quantum photonic information technology. Using a fully-optimized, periodically-poled lithium niobate microring, we demonstrate ultra-efficient sum-frequency generation on chip. The external quantum efficiency reaches $(65\pm3)\%$ with only $(104\pm4)$ $\mu$W pump power, improving the state-of-the-art by over one order of magnitude. At the peak conversion, $3\times10^{-5}$ noise photon is created during the cavity lifetime, which meets the requirement of quantum applications using single-photon pulses. Using pump and signal in single-photon coherent states, we directly measure the conversion probability produced by a single pump photon to be $10^{-5}$ -- breaking the record by 100 times -- and the photon-photon coupling strength to be 9.1 MHz. Our results mark a new milestone toward quantum nonlinear optics at the ultimate single photon limit, creating new background in highly integrated photonics and quantum optical computing.