Distributed Quantum Sensing with Multimode 𝑁⁢00⁢𝑁 States

Abstract

Distributed quantum sensing, which estimates a global parameter across distant nodes, has attracted significant interest for applications such as quantum imaging, sensor networks, and global-scale clock synchronization. 𝑁⁢00⁢𝑁 states are regarded as one of the optimal quantum resources for quantum metrology, enabling the Heisenberg scaling. Recently, the concept of 𝑁⁢00⁢𝑁 states has been extended to multimode 𝑁⁢00⁢𝑁 states for quantum-enhanced multiple-parameter estimation. However, the application of multimode 𝑁⁢00⁢𝑁 states in distributed quantum sensing remains unexplored. Here, we propose a distributed quantum sensing scheme that achieves the Heisenberg scaling using multimode 𝑁⁢00⁢𝑁 states. We theoretically show that multimode 𝑁⁢00⁢𝑁 states can reach the Heisenberg scaling by examining both the Cramér-Rao bound and the quantum Cramér-Rao bound. For experimental demonstration, we employ a four-mode 2002 state to estimate the average of two spatially distributed phases, achieving a 2.74 dB sensitivity enhancement over the standard quantum limit. We believe that utilizing multimode 𝑁⁢00⁢𝑁 states for distributed quantum sensing offers a promising approach for developing entanglement-enhanced sensor networks.