  Exceptional points are degeneracies in non-Hermitian systems. A two-state
system with parity-time (PT) symmetry usually has only one exceptional point
beyond which the eigenmodes are PT-symmetry broken. The so-called symmetry
recovery, i.e., eigenmodes become PT-symmetric again, typically occurs in
multi-state systems. Here we show that a two-state ferromagnetic waveguide
system can have an exceptional point and a subsequent symmetry recovery due to
the presence of accidental degeneracy points when the system is lossless. By
introducing a parameter space where both exceptional points reside, we designed
a system in which the trajectory in the parameter space can be controlled in
situ using an adiabatically tunable external field, allowing us to explore the
topological and chiral character of the system by encircling zero, one or two
exceptional points. We performed microwave experiments to demonstrate the
presence of the exceptional point, symmetry recovery, and the effects arising
from their dynamical encircling.
