Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath: A non-markovian approach beyond the rotating-wave approximation

Understand

We use a non-Markovian approach to study the decoherence dynamics of a qubit in either a low- or high-frequency bath modeling the qubit environment.

• This approach is based on a unitary transformation and does not require the rotating-wave approximation.
• We show that for low-frequency noise, the bath shifts the qubit energy towards higher energies (blue shift), while the ordinary high-frequency cutoff Ohmic bath shifts the qubit energy towards lower energies (red shift).
• In order to preserve the coherence of the qubit, we also investigate the quantum Zeno effect in two cases: low- and high-frequency baths.