Distributed quantum sensing in a network – EQUINE

Quantum metrology has brought significant improvements in sensitivity and precision over the use of classical resources in recent years, revolutionising certain fields such as magnetometry based on NV centre ensembles, and geophysics, thanks to cold-atom-based gravimeters. Most of these achievements, however, are based on the interaction of no more than two particles, thus limiting the corresponding geographical coverage of the sensors. EQUINE proposes a paradigm shift by promoting the development of a network of quantum sensors distributed over appreciable distances, together with the exploration of applications that exploit such networks.
More specifically, EQUINE has the following objectives: to use high-performance bipartite entangled states for the task of secure delegation of sensing; to demonstrate that measuring a global parameter of a system (sum, difference, average of multiple phase values) using a high-dimensional quantum state is more accurate than if the different sensors had been probed by separate sources (quantum or classical); to exploit multipartite entangled states to ensure the security of measurements taken at different points in a network; to leverage well-mastered telecom technology for demonstrating the feasibility of such tasks over deployed optical fibre networks, including a case study of simulated seismic vibration detection. Addressing these objectives requires a strong synergy between theoretical considerations and experimental constraints. In terms of resources, we will consider two types of multimode/multipartite quantum states, namely qudits and GHZ states. The generation, manipulation, and exploitation of these types of states to demonstrate a quantum advantage for multiparameter over localised approaches and for secure delegated and distributed sensing, represent the overarching challenge of the project. This requires tackling major scientific barriers, spanning theoretical foundations to testing solutions in realistic and constrained experimental environments.
The perspectives of our approach for addressing important use cases in quantum metrology and communication has attracted the attention of major players in these fields, Thales SIX and Exail, who will provide support and share their vision on exploitation of the outcomes of EQUINE.