  Time crystals, as temporal analogs of space crystals, manifest as stable and
periodic behavior that breaks time translation symmetry. In an open quantum
system, many-body interaction subjected to dissipation allows one to develop
the time crystalline order in an unprecedented way, as refer to dissipative
time crystal. Here we report the observation of a time crystal comb in the
continuously driven-dissipative and strongly interacting Rydberg thermal gas,
in which continuous time crystal and sub-harmonics of limit cycles as well as
the high-order harmonic oscillation phases are observed in the same system by
manipulating the Rydberg excitation. Our work provides new ways to explore the
nonequilibrium phases of matter in open systems. Such time crystals with
persistent oscillation rooted in emergent quantum correlations, may emerge as a
ubiquitous tool in quantum metrology, for instance, continuous sensing and
parameter estimation surpassing the standard quantum limit.
