On the qubit limit of cavity nonlinear optics

TL;DR

This paper explores the theoretical possibility of using high-quality optical resonators with nonlinear materials to create coupled qubit-like states in a homogeneous medium, potentially simplifying quantum photonic circuit fabrication.

Contribution

It provides a rigorous proof, based on a recent limit theorem, that such resonator-based qubit implementation is theoretically feasible with Kerr, $$, or two-photon absorbing nonlinearities.

Findings

Theoretically demonstrates the potential of nonlinear resonators for qubit creation.

Establishes conditions under which high-quality resonators can generate qubit degrees of freedom.

Provides a rigorous mathematical foundation for future experimental exploration.

Abstract

Many proposals for solid-state photonic implementations of quantum information processing utilize high-quality optical resonators to achieve strong coupling between guided fields and heterogeneously incorporated qubits. Given the practical difficulty of accurately placing quantum dots, vacancy centers, or other such atom-like emitters throughout a complex nanophotonic circuit, it would be natural to consider whether high-quality resonators could be used in conjunction with bulk optical nonlinearities to create optically-coupled qubit degrees of freedom via lithographic patterning of a homogeneous medium. A recent limit theorem for quantum stochastic differential equations can be used to prove rigorously that this should be possible, in principle, using resonators incorporating a strongly Kerr-nonlinear, $\chi^{(2)}$-nonlinear, or two-photon absorbing material with very low loss at the fundamental optical wavelength.