Improving the future detectability and inference of binary neutron star post-merger signals with photon counting readout schemes

Modern designs of gravitational-wave interferometers rely on homodyne readout techniques to extract information about the observed gravitational-wave strain. However, these designs' sensitivities are limited by quantum shot noise from mid- to high-frequencies. Recent studies have presented the possibility of implementing filter cavities to directly count photons – thereby removing the presence of shot noise – that could be associated with the presence of a stochastic gravitational-wave background. In this study, we demonstrate the further utility of a photon counting readout scheme for the future of transient gravitational-wave astronomy by focusing on its application to binary neutron star post-merger detection and inference. We simulate an ensemble of realistic, low signal-to-noise ratio post-merger signals and compare inferences from both readout methods. We find that photon counting will significantly improve the chances of detection for the low signal-to-noise ratio post-merger signals expected during the era of third generation gravitational-wave detectors.