Spectro-temporally tailored Non-Gaussian Quantum Operations in Thin-Film Waveguides

TL;DR

This paper presents a novel inverse-design framework for implementing mode-selective non-Gaussian quantum operations, such as photon subtraction and addition, in thin-film lithium niobate waveguides, advancing scalable quantum photonics.

Contribution

It introduces a new design methodology for mode-selective SPS and SPA using thin-film waveguides, leveraging dispersion engineering and inverse optimization techniques.

Findings

Achieved high mode selectivity and state purity in simulations.

Demonstrated the potential for high-fidelity non-Gaussian operations in integrated photonics.

Validated the approach on metallic waveguide models.

Abstract

Advancements in photonic platforms have enabled the precise control of light's spectral and temporal degrees of freedom, a capability crucial for the development of scalable quantum information systems. In this work, we address the challenge of implementing spectro-temporal mode-selective non-Gaussian quantum operations, specifically single-photon subtraction (SPS) and addition (SPA), in the telecom wavelength regime. Building on prior experimental demonstrations of mode-selective near-infrared SPS, we present the first design framework for achieving mode-selective SPA and SPS using thin-film lithium niobate nonlinear waveguide platforms. We introduce an inverse-design optimization scheme by modeling the quantum-optical response via the Joint Spectral Amplitude and Transfer Function, in order to identify optimal waveguide and pump parameters that maximize mode selectivity and state purity. This approach is first tested on a metallic waveguide design. We then exploit the dispersion engineering capabilities of thin-film waveguides, which offer enhanced nonlinear interactions through tighter light confinement. Our findings demonstrate that tailored nonlinear processes, particularly parametric down-conversion and frequency up-conversion, can support high-fidelity non-Gaussian operations essential for next-generation quantum photonic networks.