Quantum-enhanced multiparameter estimation in multiarm interferometers

TL;DR

This paper explores quantum-enhanced multiphase estimation in multiarm interferometers, identifying entanglement conditions and demonstrating improved sensitivity with specific quantum states in multiarm Mach-Zehnder setups.

Contribution

It establishes conditions for useful entanglement in multiphase estimation and applies them to multiarm interferometers, highlighting practical quantum states that outperform separable states.

Findings

Useful entanglement enhances multiphase estimation sensitivity.

Multimode Fock states outperform separable states in multiarm interferometers.

Implementation is feasible with current integrated photonics technology.

Abstract

Quantum metrology is the state-of-the-art measurement technology. It uses quantum resources to enhance the sensitivity of phase estimation beyond what reachable within classical physics. While single parameter estimation theory has been widely investigated, much less is known about the simultaneous estimation of multiple phases, which finds key applications in imaging and sensing. In this manuscript we provide conditions of useful entanglement (among multimode particles, qudits) for multiphase estimation and adapt them to multiarm Mach-Zehnder interferometry. We discuss benchmark multimode Fock states containing useful qudit entanglement and overcoming the sensitivity of separable qudit states in three and four arm Mach-Zehnder-like interferometers - currently within the reach of integrated photonics technology.