Optimizing Entanglement to attain Quantum Limit of Long-Baseline Imaging

This project addresses fundamental research on one of the potentially-strongest use-cases of distributed entanglement—that of enhancing the performance of a network of sensors trying to work together to solve one task—specifically in the context of long-baseline imaging. This ambitious project brings together two lines of research our group has led in recent years–receiver designs to attain quantum limits of passive imaging (funded primarily by DARPA), and entanglement-enhanced photonic sensors (funded primarily by ONR)—to develop a thorough fundamental understanding, and practical system designs, for entanglement enhanced long-baseline imaging at the quantum-performance limit. Our research objectives are broken into three tasks, as described below.

Task 1 - Entanglement assisted general distributed parameter estimation: We explore the use of distributed multi-site entanglement and local quantum operations and measurements, and classical communications among sensor sites, to attain the quantum limits of estimation accuracy of any predefined parameter that is a global function of the locally-collected light by the sensors. This theory is then applied to find the specific entanglement necessary and the local operations and classical communications (LOCC) algorithms, to attain – for long-baseline imaging – a recently-quantified fundamental quantum limit, for a general passive imaging parameter detection and estimation task involving incoherent broadband radiation, by a long-baseline telescope system (of given telescope diameters and baseline geometry) in the traditionally unresolvable sub-Rayleigh regime.
Task 2 - Practical design and performance evaluation of entanglement enhanced long-baseline interferometric imaging: We will design a system that approaches the quantum limit evaluated in Task 1 – for passive imaging problems of interest to the USAF – such as discriminating prior-known objects under dimly-lit conditions with applications to GEO object detection and earth-based remote sensing – but with that system built with readily available quantum technology, e.g., spontaneous parametric downconversion (SPDC)-based photonic entanglement sources, Silicon vacancy color-center based quantum memories [being built for quantum repeater development for long-distance entanglement distribution as part of the NSF-ERC Center for Quantum Networks (CQN)], volumetric spatial mode sorters (being designed and built in our group using a spatial light modulator (SLM)), optical fibers, switches, and shot-noise-limited single photon detectors. This task will quantify, for real-life imaging and object detection/estimation problems, how much actual improved performance could an entanglement-assisted system afford, as compared with a traditional interferometric-based long-baseline imaging system.
Task 3 - Experimental proof-of-concept validation of concept: In this task, we will demonstrate, time and resources permitting, quantum enhanced multi-aperture image-data detection and estimation, in a proof-of-concept emulated laboratory experiment, for a two-aperture setting for a simple problem such as estimating the angular separation between two pointlike incoherent emitters. This experiment will employ SLM-based mode sorters we have built, and a programmable nanophotonic linear-optical processor attached to a HG-basis mode sorter purchased from CaiLabs.