Cubic nonlinear squeezing and its decoherence

TL;DR

This paper investigates the robustness of cubic nonlinear squeezing in quantum harmonic oscillator states under decoherence, emphasizing the importance of initial state optimization for practical quantum technology applications.

Contribution

It introduces the concept of nonlinear squeezing, analyzes its stability under loss and dephasing, and discusses how initial parameters can be optimized for robustness.

Findings

Nonlinear squeezing can be achieved below the noise threshold for all quadratic Hamiltonians.

The stability of nonlinear squeezed states depends on initial parameters.

Optimized initial states enhance robustness against decoherence.

Abstract

Squeezed states of the harmonic oscillator are a common resource in applications of quantum technology. If the noise is suppressed in a nonlinear combination of quadrature operators below threshold for all possible up-to-quadratic Hamiltonians, the quantum states are non-Gaussian and we refer to the noise reduction as nonlinear squeezing. Non-Gaussian aspects of quantum states are often more vulnerable to decoherence due to imperfections appearing in realistic experimental implementations. Therefore, a stability of nonlinear squeezing is essential. We analyze the behavior of quantum states with cubic nonlinear squeezing under loss and dephasing. The properties of nonlinear squeezed states depend on their initial parameters which can be optimized and adjusted to achieve the maximal robustness for the potential applications.