Kerr-induced non-Gaussianity of ultrafast bright squeezed vacuum

TL;DR

This paper demonstrates the deterministic generation of bright non-Gaussian states of light via Kerr nonlinearity applied to bright squeezed vacuum, with potential applications in quantum computing and metrology.

Contribution

It introduces a method to produce bright non-Gaussian states deterministically using Kerr nonlinearity on BSV, characterized by Husimi function sampling and analysis of non-Gaussian features.

Findings

Transformation from Gaussian to non-Gaussian profile observed

Kerr-induced Wigner negativity is tolerant to optical loss in some states

Bridges quantum optics and ultrafast nonlinear optics for high photon flux applications

Abstract

Non-Gaussian states of light are a critical resource for fault-tolerant quantum computing and enhanced metrology, but are typically faint and often obtained via post-selection. Here, we demonstrate the deterministic generation of a bright non-Gaussian state by introducing a Kerr nonlinearity to a macroscopic state of light called bright squeezed vacuum (BSV). To characterize the resulting state, we use a single-shot f-2f interferometer to sample its Husimi function. We observe a clear transformation from a 2D Gaussian distribution to an 'S'-shaped non-Gaussian profile, which is the direct statistical evidence of the intensity-dependent nonlinear phase. The negativity of the Wigner function, which is an intrinsic property of any pure non-Gaussian state, cannot be observed because BSV is a mixed state even under minute optical loss. However, we show that BSV can be considered as a mixture of pure squeezed coherent states, for some of which Kerr-induced Wigner-function negativity is quite tolerant to loss. This work bridges the gap between quantum optics and ultrafast nonlinear optics, opening a path to quantum applications that require high photon flux.