Surpassing Quantum Noise Limits with Nonlinear Amplification

TL;DR

This paper introduces a nonlinear quantum amplification method that surpasses the fundamental noise limits of traditional linear amplifiers, enabling enhanced signal-to-noise ratios for quantum technologies.

Contribution

It presents a novel nonlinear amplification approach leveraging Kerr nonlinearity and coupled bosonic modes to exceed quantum noise limits in signal amplification.

Findings

Demonstrates surpassing quantum noise limits in SNR

Uses Kerr nonlinearity for signal gain enhancement

Applicable to quantum information and metrology

Abstract

Linear quantum amplifiers are indispensable tools for quantum technologies, yet their performance is fundamentally limited by quantum noise, precluding any signal-to-noise ratio (SNR) enhancement unless supplemented by post-selection or non-classical resources. To surpass this limitation, we propose a nonlinear quantum amplification strategy that exploits the interplay between a gain-stabilized bright eigenmode of a coupled two-mode bosonic system and Kerr nonlinearity. We demonstrate that this interplay enables the signal gain to surpass the noise gain in a selected quadrature, leading to a net increase in the SNR beyond the quantum limits of conventional linear amplifiers. Our work thus establishes a novel nonlinear amplification paradigm capable of enhancing the SNR, with promising applications across quantum information processing, quantum communications, and quantum metrology.