Efficient generation of entangled photons in the telecommunications range using nonlinear metasurfaces integrated with ScAlN/GaN heterostructures

TL;DR

This paper introduces a novel, highly efficient entangled photon source in the telecom range using integrated nonlinear metasurfaces with ScAlN/GaN heterostructures, promising advances in quantum technologies.

Contribution

It presents a new integrated photon source leveraging nonlinear metasurfaces and ScAlN/GaN heterostructures, achieving high biphoton rates in a compact form.

Findings

Achieves over 10^{10} entangled photon pairs per second.

Utilizes strain-compensated delta-doped ScAlN barriers for high nonlinearity.

Demonstrates mitigation of strain issues in nitride heterostructures for IR and visible wavelengths.

Abstract

Entangled photons provide non-classical correlations that enable measurement sensitivities beyond classical limits, scalable fault-tolerant quantum computation, and fundamentally secure quantum communication, making them a foundational necessity for next-generation quantum technologies. Here we propose and analyze a novel source of entangled photons based on ScAlN/GaN quantum wells integrated with dielectric metasurfaces. Giant second-order intersubband nonlinearity of the GaN quantum wells with strain-compensated delta-doped ScAlN barriers caused by strong built-in electric fields combined with superior mode-coupling performance of metasurfaces optimized by inverse design give rise to efficient parametric down-conversion and generation of entangled photons in the telecom range. We develop a rigorous Heisenberg-Langevin formalism which includes field quantization, dissipation and fluctuations for all fields, parametric amplification of thermal noise and zero-point fluctuations, and other relevant effects. Our proposed approach of employing the emergent photonic material ScAlN promises high biphoton generation rate over $10^{10}$ s$^{-1}$ from a compact integrated structure that is only 0.5 $\mu$m thick while mitigating strain-related issues that have so far impeded progress of nitride-based heterostructures for quantum photonic applications into the infrared and visible wavelengths. Our result therefore is relevant for numerous applications ranging from quantum sensing, quantum information, and computing.