  Fluctuations associated with relaxations in far-from-equilibrium regime is of
fundamental interest for a large variety of systems within broad scales. Recent
advances in techniques such as spectroscopy have generated the possibility for
measuring the fluctuations of the mesoscopic systems in connection to the
relaxation processes when driving the underlying quantum systems far from
equilibrium. We present a general nonequilibrium Fluctuation-Dissipation
Theorem (FDT) for quantum Markovian processes where the detailed-balance
condition is violated. Apart from the fluctuations, the relaxation involves
extra correlation that is governed by the quantum curl flux emerged in the
far-from-equilibrium regime. Such a contribution vanishes for the thermal
equilibrium, so that the conventional FDT is recovered. We finally apply the
nonequilibrium FDT to the molecular junctions, elaborating the
detailed-balance-breaking effects on the optical transmission spectrum. Our
results have the advantage of and exceed the scope of the
fluctuation-dissipation relation in the perturbative and near equilibrium
regimes, and is of broad interest for the study of quantum thermodynamics.ation
in the perturbative and near equilibrium regimes, and is of broad interest for
the study of quantum thermodynamics.
