Utilizing probabilistic entanglement between sensors in quantum networks

TL;DR

This paper investigates how probabilistic entanglement in quantum sensor networks can enhance parameter estimation, identifying thresholds where entanglement improves sensing and strategies for its optimal use under realistic conditions.

Contribution

It models a star quantum network with probabilistic entanglement, analyzing protocols for optimal resource utilization based on fidelity and success probability.

Findings

Entanglement improves sensing above a fidelity threshold.

Without distillation, low-fidelity entanglement favors classical sensing.

Guidelines for when to use, store, or distill entanglement in networks.

Abstract

One of the most promising applications of quantum networks is entanglement assisted sensing. The field of quantum metrology exploits quantum correlations to improve the precision bound for applications such as precision timekeeping, field sensing, and biological imaging. When measuring multiple spatially distributed parameters, current literature focuses on quantum entanglement in the discrete variable case, and quantum squeezing in the continuous variable case, distributed amongst all of the sensors in a given network. However, it can be difficult to ensure all sensors pre-share entanglement of sufficiently high fidelity. This work probes the space between fully entangled and fully classical sensing networks by modeling a star network with probabilistic entanglement generation that is attempting to estimate the average of local parameters. The quantum Fisher information is used to determine which protocols best utilize entanglement as a resource for different network conditions. It is shown that without entanglement distillation there is a threshold fidelity below which classical sensing is preferable. For a network with a given number of sensors and links characterized by a certain initial fidelity and probability of success, this work outlines when and how to use entanglement, when to store it, and when it needs to be distilled.