  Advancing quantum sensing tools for investigating systems at atomic and
nanoscales is crucial for the progress of quantum technologies. While numerous
protocols employ quantum probes to extract information from stationary or
weakly coupled environments, the challenges intensify at atomic- and
nano-scales where the environment is inherently out-of-equilibrium or strongly
coupled with the sensor. We here prove that the time-reversal symmetry in the
quantum-sensor control dynamics is broken, when partial information is probed
from an environment that is out-of-equilibrium with non stationary fluctuations
or is described by quantum non-Gaussian, strongly coupled environmental
correlations. We exploit this phenomenon as a quantum sensing paradigm with
proof-of principle experimental quantum simulations using solid-state nuclear
magnetic resonance (NMR). This introduces a signal contrast on a qubit-probe
that quantifies how far the sensed environment is from equilibrium or its
quantum non-Gaussian nature. Protocols are also presented to discern and filter
a variety of environmental properties including stationary, non-stationary and
non-Gaussian quantum noise fluctuations as a step toward sensing the ubiquitous
environments of a quantum-sensor at atomic and nanoscales.
