High-efficiency On-chip Quantum Photon Source in Modal Phase-matched Lithium Niobate Nanowaveguide

TL;DR

This paper demonstrates a highly efficient on-chip quantum photon source using modal phase matching in dual-layer lithium niobate nanowaveguides, achieving high pair generation rates and low noise for scalable quantum information processing.

Contribution

It introduces a novel modal phase matching technique in dual-layer LNOI waveguides, overcoming limitations of periodic poling for efficient on-chip quantum photon generation.

Findings

Photon pair generation rate of 41.77 GHz/mW

Coincidence-to-accidental ratio up to 58298

Heralded single-photon rate over 100 kHz

Abstract

Thin-film lithium niobate on insulator~(LNOI) emerges as a promising platform for integrated quantum photon source, enabling scalable on-chip quantum information processing. The most popular technique to overcome the phase mismatching between interacting waves in waveguide is periodic poling, which is intrinsically sensitive to poling uniformity. Here, we report an alternative strategy to offset the phase mismatching of spontaneous parametric down-conversion~(SPDC) process, so-called modal phase matching, in a straight waveguide fabricated on a dual-layer LNOI. The dual-layer LNOI consists of two 300~nm lithium niobates with opposite directions, which significantly enhances the spatial overlap between fundamental and high-order modes and thus enables efficient SPDC. This dual-layer waveguide generates photon pairs with pair generation rate of 41.77~GHz/mW, which exhibits excellent signal-to-noise performance with coincidence-to-accidental ratio up to 58298$\pm$1297. Moreover, we observe a heralded single-photon source with second-order autocorrelation $g_{H}^{(2)}(0)<0.2$ and heralded rate exceeding 100~kHz. Our results provide an experiment-friendly approach for efficient generation of quantum photon sources and benefit the on-chip quantum information processing based on LNOI.