Non-Gaussian photonic state engineering with the quantum frequency processor

TL;DR

This paper presents a versatile method for generating non-Gaussian quantum states of light using a quantum frequency processor, enabling efficient production of complex states like Schrödinger cat states in frequency bins.

Contribution

It introduces a general framework combining frequency-based quantum information and non-Gaussian state preparation, with a theoretical model and optimized circuit designs.

Findings

Designed circuits for Schrödinger cat states production

Analyzed performance tradeoffs for different circuit configurations

Provided a numerical optimization approach for state engineering

Abstract

Non-Gaussian quantum states of light are critical resources for optical quantum information processing, but methods to generate them efficiently remain challenging to implement. Here we introduce a generic approach for non-Gaussian state production from input states populating discrete frequency bins. Based on controllable unitary operations with a quantum frequency processor, followed by photon-number-resolved detection of ancilla modes, our method combines recent developments in both frequency-based quantum information and non-Gaussian state preparation. Leveraging and refining the K-function representation of quantum states in the coherent basis, we develop a theoretical model amenable to numerical optimization and, as specific examples, design quantum frequency processor circuits for the production of Schr\"{o}dinger cat states, exploring the performance tradeoffs for several combinations of ancilla modes and circuit depth. Our scheme provides a valuable general framework for producing complex quantum states in frequency bins, paving the way for single-spatial-mode, fiber-optic-compatible non-Gaussian resource states.