Entanglement assisted fiber sensor network

In this project, we are developing a remotely distributed sensing system based on fiber networks enhanced by quantum entanglement. This distributed quantum-enhanced sensing network will boost the sensitivity of measuring, e.g., mechanical, thermal, and electrical signals for critical naval applications, using squeezed light that is combined with coherent light, and split using a fiber splitter into a continuous-variable entangled state. We will distribute such continuous variable multi-site quantum entanglement across a campus-wide fiber network at the University of Maryland—the MARQI network—built on the NSF QuANNECT program led by Prof. Edo Waks that PI Dr. Guha is a co-PI on, and performing collective measurements at multiple remote sensor sites, after distributing the aforesaid squeezed-light enabled entanglement, whose development will be led by co-PI Dr. Fan of UT Austin. This remotely distributed quantum-enhanced sensing network will enable obtaining a given fidelity of signal detection and processing with a much smaller integration time and lower optical power level than a classical sensing network. Besides detecting external signals, the distributed quantum-enhanced sensing technology can also be used for network tomography, such as measuring the intrinsic properties of the fiber network including the loss and dispersion of each fiber link. Examples of network-tomography tasks of potential interest to the US Navy includes: (a) quick detection of topology changes, e.g., caused due to link failures, in a hybrid free-space/fiber dynamic environment, and (b) assessment of communication channel quality between two distant users connected by a multi-hop network without probing the intermediary nodes.

The specific research being conducted on this project includes the development of fiber-compatible continuous-variable quantum entanglement sources, low-loss fiber Bragg grating (FBG) based sensors, and high-efficiency low-noise detectors for the distributed quantum-enhanced sensing network. Our experimental demonstration will include a remotely distributed quantum-enhanced sensing network based on the fiber network across the University of Maryland campus to show sensitivity improvement in a sensing application such as estimating and tracking a temperature gradient, structural health evaluation of the network, and distributed RF signal detection. In addition, we will develop a theoretical framework to estimate the sensing performance limit and seek the optimum quantum entanglement structure for the remotely distributed quantum-enhanced sensing network for different global functions of individually-sensed parameters of interest, focusing exclusively on scenarios where all-optical entanglement generated using squeezed light sources, linear optical elements, along with homodyne and single photon detectors suffice. Finally, we will explore new protocols to perform fiber network tomography using quantum entanglement with minimum measurement trials and resources.