Observer dependence of photon bunching: The influence of the relativistic redshift on Hong-Ou-Mandel interference

We study the influence of the relativistic redshift on Hong-Ou-Mandel (HOM) interference and present a genuine quantum test of general relativity. We use Glauber???s theory of quantum coherence to predict the coincidence probability of realistic broadband photons in HOM experiments in a nonrelativistic setting. We extend the quantum field theoretical framework previously developed to describe the deformation of the spectral profile of single photons in curved spacetimes to a multiphoton framework, which is exact for inertial observers in a flat spacetime and an approximation when observers are located in a curved spacetime. We find that, in case of frequency entangled photons, a mutual redshift between the sender and the receiver can change the coincidence statistics from photon bunching to photon antibunching and vice versa. This implies that the (anti)symmetry of the photonic spectral wave function is an observer dependent notion and that this can be probed via HOM experiments in a relativistic setting.

Automated summary

We study the influence of the relativistic redshift on Hong-Ou-Mandel (HOM) interference and present a genuine quantum test of general relativity. We use Glauber's theory of quantum coherence to predict the coincidence probability of realistic broadband photons in HOM experiments and extend the quantum field theoretical framework to describe the deformation of the spectral profile of multiple photons. The results show that the mutual redshift between sender and receiver can switch the coincidence statistics from photon bunching to photon antibunching and vice versa.