  Open quantum systems undergo decoherence, which is responsible for the
transition from quantum to classical behavior. The time scale in which
decoherence takes place can be analyzed using upper limits to its rate. We
examine the dynamics of open chaotic quantum systems governed by random
Lindblad operators sourced from Gaussian and Ginibre ensembles with
Wigner-Dyson symmetry classes. In these systems, the ensemble-averaged purity
decays monotonically as a function of time. This decay is governed by the
decoherence rate, which is upper-bounded by the dimension of their Hilbert
space and is independent of the ensemble symmetry. These findings hold upon
mixing different ensembles, indicating the universal character of the
decoherence rate limit. Moreover, our findings reveal that open chaotic quantum
systems governed by random Lindbladians tend to exhibit the most rapid
decoherence, regardless of the initial state. This phenomenon is associated
with the concentration of the decoherence rate near its upper bound. Our work
identifies primary features of decoherence in dissipative quantum chaos, with
applications ranging from quantum foundations to high-energy physics and
quantum technologies.
