Quantum Metrological Power of Continuous-Variable Quantum Networks

TL;DR

This paper demonstrates that continuous-variable quantum networks can generate entanglement enabling Heisenberg-limited distributed sensing, with robustness to photon loss and practical implementation via local operations.

Contribution

It reveals the quantum metrological advantage of CV quantum networks for distributed sensing, including conditions for robustness and practical schemes.

Findings

CV quantum networks enable Heisenberg scaling in distributed sensing

Entanglement in CV networks surpasses unentangled probes

Quantum enhancement persists under certain photon-loss conditions

Abstract

We investigate the quantum metrological power of typical continuous-variable (CV) quantum networks. Particularly, we show that most CV quantum networks provide an entanglement to quantum states in distant nodes that enables one to achieve the Heisenberg scaling in the number of modes for distributed quantum displacement sensing, which cannot be attained using an unentangled probe state. Notably, our scheme only requires local operations and measurements after generating an entangled probe using the quantum network. In addition, we find a tolerable photon-loss rate that maintains the quantum enhancement. Finally, we numerically demonstrate that even when CV quantum networks are composed of local beam splitters, the quantum enhancement can be attained when the depth is sufficiently large.