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

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, 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.