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

Abstract

Abstract Interferometric telescopes are instrumental for the imaging of distant astronomical bodies, but
optical loss heavily restricts how far telescopes in an array can be placed from one another, leading
to a bottleneck in the resolution that can be achieved. An entanglement-assisted approach to this
problem 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 can
be distributed across long distances by employing a quantum repeater network. In this paper, we
propose an alternative entanglement-assisted scheme that interferes a two-mode squeezed vacuum
state with the astronomical state and then measures the resulting state by means of homodyne
detection. We use a continuous-variable approach and compute the Fisher information with respect
to the mutual coherence of the astronomical source. We show that when the Fisher information is
observed cumulatively at the rate at which successful measurements can be performed, our proposed
scheme does not outperform the traditional direct detection approach or the entanglement-assisted
approach of GJC12.