Bright squeezed vacuum in a nonlinear interferometer: frequency/temporal Schmidt-mode description

TL;DR

This paper develops an analytical frequency-domain model for bright squeezed vacuum in nonlinear interferometers, revealing how phase, dispersion, and gain influence its spectral properties and enabling better control for quantum optics applications.

Contribution

It introduces a novel analytical approach using Bloch-Messiah reduction and Schmidt modes to describe BSV in nonlinear interferometers, especially under high gain conditions.

Findings

Spectral properties depend nontrivially on phase, dispersion, and gain.

Significant spectral changes occur as parametric gain increases.

Provides insights into tailoring BSV for quantum applications.

Abstract

Control over the spectral properties of the bright squeezed vacuum (BSV), a highly multimode non-classical macroscopic state of light that can be generated through high-gain parametric down conversion, is crucial for many applications. In particular, in several recent experiments BSV is generated in a strongly pumped SU(1,1) interferometer to achieve phase supersensitivity, perform broadband homodyne detection, or tailor the frequency spectrum of squeezed light. In this work, we present an analytical approach to the theoretical description of BSV in the frequency domain based on the Bloch-Messiah reduction and the Schmidt-mode formalism. As a special case we consider a strongly pumped SU(1,1) interferometer. We show that different moments of the radiation at its output depend on the phase, dispersion and the parametric gain in a nontrivial way, thereby providing additional insights on the capabilities of nonlinear interferometers. In particular, a dramatic change in the spectrum occurs as the parametric gain increases.