  Quantum speed limit (QSL) time for open systems driven by classical fields is
studied in the presence of thermal bosonic environments. The decoherence
process is quantitatively described by the time-convolutionless master
equation. The evolution speed of an open system is related not only to the
strength of driving classical field but also to the environmental temperature.
The energy-state population plays a key role in the thermal QSL. Comparing with
the zero-temperature reservoir, we predict that the structural reservoir at low
temperatures may contribute to the acceleration of quantum decoherence. The
manifest oscillation of QSL time takes on under the circumstance of classical
driving fields. We also investigate the scaling property of QSL time for
multi-particle noninteracting entangled systems. It is demonstrated that
entanglement of open systems can be considered as one resource for improving
the potential capacity of thermal quantum speedup.
