A 3.9 km baseline intensity interferometry photon counting experiment

TL;DR

This paper reports on a 3.9 km baseline intensity interferometry experiment using ultrafast photon counting photometers, achieving high time accuracy to measure photon correlations over large distances.

Contribution

It introduces a novel long-baseline intensity interferometry setup with ultrafast photon counters on separate telescopes, enabling precise photon correlation measurements.

Findings

Initial successful synchronization of photon detectors over 3.9 km

Preliminary photon intensity correlation measurements obtained

Demonstration of feasibility for long-baseline optical interferometry

Abstract

In the last years we have operated two very similar ultrafast photon counting photometers (Iqueye and Aqueye+) on different telescopes. The absolute time accuracy in time tagging the detected photon with these instruments is of the order of 500 ps for hours of observation, allowing us to obtain, for example, the most accurate ever light curve in visible light of the optical pulsars. Recently we adapted the two photometers for working together on two telescopes at Asiago (Italy), for realizing an Hanbury-Brown and Twiss Intensity Interferometry like experiment with two 3.9 km distant telescopes. In this paper we report about the status of the activity and on the very preliminary results of our first attempt to measure the photon intensity correlation.