Multiparameter squeezing for optimal quantum enhancements in sensor networks

TL;DR

This paper introduces multiparameter squeezing as a new framework for quantum-enhanced precision measurements involving multiple unknown parameters, extending existing single-parameter squeezing concepts to more complex sensing scenarios.

Contribution

It develops the operational concept of multiparameter squeezing, identifying useful states and strategies for optimal estimation in multi-parameter quantum metrology.

Findings

Generalized spin- and quadrature-squeezing parameters for multiple parameters

Provided bounds and strategies for multiparameter quantum estimation

Facilitated characterization of multimode quantum states in sensor networks

Abstract

Squeezing currently represents the leading strategy for quantum enhanced precision measurements of a single parameter in a variety of continuous- and discrete-variable settings and technological applications. However, many important physical problems including imaging and field sensing require the simultaneous measurement of multiple unknown parameters. The development of multiparameter quantum metrology is yet hindered by the intrinsic difficulty in finding saturable sensitivity bounds and feasible estimation strategies. Here, we derive the general operational concept of multiparameter squeezing, identifying metrologically useful states and optimal estimation strategies. When applied to spin- or continuous-variable systems, our results generalize widely-used spin- or quadrature-squeezing parameters. Multiparameter squeezing provides a practical and versatile concept that paves the way to the development of quantum-enhanced estimation of multiple phases, gradients, and fields, and for the efficient characterization of multimode quantum states in atomic and optical sensor networks.