Eur. Phys. J. D (2012) 66: 8
https://doi.org/10.1140/epjd/e2011-20008-5

Regular Article

The quantum stellar interferometer

¹ 60 rue des Bergers, 75015 Paris, France
² Université de Liège, 17 allée du 6 Août, 4000 Sart Tilman, Belgium

^a e-mail: riaud.pierre@gmail.com

Received: 4 January 2011
Received in final form: 4 July 2011
Published online: 11 January 2012

Abstract

In this paper we propose a new interferometric scheme using photon entanglement. The two main limitations of stellar interferometry are (a) the small sensitivity and (b) the need for long delay-lines to compensate the path difference between the telescopes during observing runs. Entangled-photon pairs, generated by spontaneous parametric down-conversion, open the way to measuring quantum states correlation in the near infrared between two spatially separated telescopes and at very high sensitivities (down to a few stellar photons), thanks to a new interferometric layout which does not make use of complex long delay-lines. A femtosecond laser coupled to a nonlinear crystal is used as a local oscillator to perform the double homodyne measurements. This new quantum interferometer allows to measure astronomical objet sizes with very high angular resolution down to μas level.