  Exceptional points (EPs), i.e. branch point singularities of non-Hermitian
Hamiltonians, are ubiquitous in optics. So far, the signatures of EPs have been
mostly studied assuming classical light.
  In the passive parity-time ($\mathcal{PT}$) optical coupler, a fingerprint of
EPs resulting from the coalescence of two resonance modes is a qualitative
change of the photon decay law, from damped Rabi-like oscillations to
transparency, as the EP is crossed by increasing the loss rate. However, when
probed by non-classical states of light, quantum interference can hide EPs.
Here it is shown that, under excitation with polarization-entangled two-photon
states, EP phase transition is smoothed until to disappear as the effective
particle statistics is changed from bosonic to fermionic.
