Practical Approach to Extending Baselines of Telescopes using Continuous-VariableQuantum Information

Abstract Interferometric telescopes are instrumental for the imaging of distant astronomical bodies, butoptical loss heavily restricts how far telescopes in an array can be placed from one another, leadingto a bottleneck in the resolution that can be achieved. An entanglement-assisted approach to thisproblem has been proposed by Gottesman, Jennewein, and Croke (GJC12) Physical Review Letters,109(7):070503, July 2011, as a possible solution to the issue of optical loss if the entangled state canbe distributed across long distances by employing a quantum repeater network. In this paper, wepropose an alternative entanglement-assisted scheme that interferes a two-mode squeezed vacuumstate with the astronomical state and then measures the resulting state by means of homodynedetection. We use a continuous-variable approach and compute the Fisher information with respectto the mutual coherence of the astronomical source. We show that when the Fisher information isobserved cumulatively at the rate at which successful measurements can be performed, our proposedscheme does not outperform the traditional direct detection approach or the entanglement-assistedapproach of GJC12.