Quantum statistical signature of PT symmetry breaking

In multiparticle quantum interference, bosons show rather generally the tendency to bunch together, while fermions cannot. This behavior, which is rooted in the different statistics of the particles, results in a higher coincidence rate P for fermions than for bosons, i.e., P(bos) < P(ferm). However, in lossy systems, such a general rule can be violated because bosons can avoid lossy regions. Here it is shown that, in a rather general optical system showing passive parity–time (PT ) symmetry, at the PT symmetry breaking phase transition point, the coincidence probabilities for bosons and fermions are equalized, while in the broken PT phase, the reversal P(bos) > P(ferm) is observed. Such effect is exemplified by considering the passive PT -symmetric optical directional coupler.