Criteria for optimal entanglement-assisted long baseline imaging protocols

Abstract: Quantum-entanglement-assisted telescopy protocol have been proposed and studied as a means to extend the baseline of optical interferometric telescopes. However, determining the optimality of these quantum-assisted protocols remains an open question. Here we introduce a noval framework for systematically characterizing different entanglement-assisted telescopy protocols by integrating tools from quantum metrology with the superselection rule (SSR) from quantum information theory. In our approach, the estimation of interference fringes is rigorously quantified using the quantum Fisher information under the SSR constraint. This approach defines the fundamental limits of astronomical estimation problems with finite entanglement resources, and building on this foundation, we propose new entanglement-assisted protocols that outperform previously known methods. Moreover, we show that these protocols are compatible with linear optical technology and could potentially inspire the development of improved quantum telescopy schemes for near-term, lossy, repeater-less quantum networks.