  The interplay between strong long-range interactions and the coherent driving
contribute to the formation of complex patterns, symmetry, and novel phases of
matter in many-body systems. However, long-range interactions may induce an
additional dissipation channel, resulting in non-Hermitian many-body dynamics
and the emergence of exceptional points in spectrum. Here, we report
experimental observation of interaction-induced exceptional points in cold
Rydberg atomic gases, revealing the breaking of charge-conjugation parity
symmetry. By measuring the transmission spectrum under increasing and
decreasing probe intensity, the interaction-induced hysteresis trajectories are
observed, which give rise to non-Hermitian dynamics. We record the area
enclosed by hysteresis loops and investigate the dynamics of hysteresis loops.
The reported exceptional points and hysteresis trajectories in cold Rydberg
atomic gases provide valuable insights into the underlying non-Hermitian
physics in many-body systems, allowing us to study the interplay between
long-range interactions and non-Hermiticity.
