Enhanced Phase Estimation via Photon-Added Two-Mode Squeezed States and Kerr Nonlinearity

TL;DR

This paper proposes a quantum metrology scheme using photon-added two-mode squeezed states and Kerr nonlinearity in a Mach--Zehnder interferometer, achieving measurement precision beyond classical limits and demonstrating robustness against photon loss.

Contribution

It introduces a novel combination of photon-added states and Kerr nonlinearity to enhance phase estimation beyond standard quantum limits.

Findings

Enhanced phase sensitivity with increased photon-addition and resource strength

Surpassing the standard quantum limit and approaching/exceeding the Heisenberg limit

Improved robustness against photon loss in quantum metrology schemes

Abstract

Quantum metrology employs quantum resources to achieve measurement precision beyond classical limits. This work investigates a Mach--Zehnder interferometer incorporating a Kerr nonlinear phase shifter, with photon-added two-mode squeezed coherent states generated via four-wave mixing as input. We demonstrate that increasing both the photon-addition order and the input resource strength systematically enhances phase sensitivity, quantum Fisher information, and the corresponding quantum Cram\'er--Rao bound. The proposed system not only surpasses the standard quantum limit but also approaches or exceeds the Heisenberg limit for linear phase shifts, while Kerr nonlinearity enables surpassing the super-Heisenberg limit. Furthermore, the scheme exhibits enhanced robustness against photon loss, providing a promising pathway toward practical high-precision quantum metrology applications.