Title: Unidirectional zero reflection as gauged parity-time symmetry,
Abstract: We introduce here the concept of establishing Parity-time symmetry through a
gauge transformation involving a shift of the mirror plane for the Parity
operation. The corresponding unitary transformation on the system's
constitutive matrix allows us to generate and explore a family of equivalent
Parity-time symmetric systems. We further derive that unidirectional zero
reflection can always be associated with a gauged PT-symmetry and demonstrate
this experimentally using a microstrip transmission-line with magnetoelectric
coupling. This study allows us to use bianisotropy as a simple route to realize
and explore exceptional point behaviour of PT-symmetric or generally
non-Hermitian systems.