Title: Photonic Loschmidt echo in binary waveguide lattices,
Abstract: Time reversal is one of the most intriguing yet elusive wave phenomenon of
major interest in different areas of classical and quantum physics. Time
reversal requires in principle to flip the sign of the Hamiltonian of the
system, leading to a revival of the initial state (Loschmidt echo). Here it is
shown that Loschmidt echo of photons can be observed in an optical setting
without resorting to reversal of the Hamiltonian. We consider photonic
propagation in a binary waveguide lattice and show that, by exchanging the two
sublattices after some propagation distance, a Loschmidt echo can be observed.
Examples of Loschmidt echoes for single photon and NOON states are given in
one- and two-dimensional waveguide lattices.