Energy range for quantum coherence
Filippo Giraldi · Physical Review A · 2015
Decoherence-free states have been found in Markovian open system dynamics and in the framework of non-Markovian fermionic environments. In the latter scenario we determine an energy range where quantum coherence is maintained over long times for every initial coherent configuration. In particular, for a two-state fermionic system interacting with a non-Markovian fermionic environment, undamped oscillating or stable coherence between the two energy eigenstates appears if the degenerate energy level is below a critical energy. If these energies coincide, the same behavior is observed in the superohmic regime and, under special conditions, the initial coherence is approached asymptotically. Equivalently, coherence persists if a defined dressed energy of the system is less than the band-gap energy of the reservoir. Same properties are found in the framework of bosonic environments.