Two-photon amplitude interferometry for precision astrometry

TL;DR

This paper proposes a novel quantum interferometry technique using two-photon amplitude interference at separate stations, enabling high-precision astronomical measurements without requiring phase-stable links.

Contribution

It introduces a new method for quantum interferometry with separate stations, improving astrometric precision and reducing technical requirements compared to previous proposals.

Findings

Potential for 10 microarcsecond angular precision in one night

Comparison with Hanbury Brown & Twiss interferometry shows advantages

Theoretical calculations support feasibility for bright stars

Abstract

Improved quantum sensing of photons from astronomical objects could provide high resolution observations in the optical benefiting numerous fields, including general relativity, dark matter studies, and cosmology. It has been recently proposed that stations in optical interferometers would not require a phase-stable optical link if instead sources of quantum-mechanically entangled pairs could be provided to them, potentially enabling hitherto prohibitively long baselines. A new refinement of this idea is developed, in which two photons from different sources are interfered at two separate and decoupled stations, requiring only a slow classical information link between them. We rigorously calculate the observables and contrast this new interferometric technique with the Hanbury Brown & Twiss intensity interferometry. We argue this technique could allow robust high-precision measurements of the relative astrometry of the two sources. A basic calculation suggests that angular precision on the order of $10$~microarcsecond in the relative opening angle could be achieved in a single night's observation of two bright stars.