Effect of a gap on the decoherence of a qubit

Abstract

We revisit the problem of the decoherence and relaxation of a central spin coupled to a bath of conduction electrons. We consider both metallic and semiconducting baths to study the effect of a gap in the bath density of states (DOS) on the time evolution of the density matrix of the central spin. We use two weak coupling approximation schemes to study the decoherence. At low temperatures, though the temperature dependence of the decoherence rate in the case of a metallic bath is the same irrespective of the details of the bath, the same is not true for the semiconducting bath. We also calculate the relaxation and decoherence rates as a function of external magnetic fields applied both on the central spin and the bath. We find that in the presence of the gap, there exists a certain regime of fields, for which surprisingly, the metallic bath has lower rates of relaxation and decoherence than the semiconducting bath.

9 pages, 9 figures

References in corpus (5)

• Non-Markovian dynamics in a spin star system: Exact solution and approximation techniques
• Spin Precession and Real Time Dynamics in the Kondo Model: A Time-Dependent Numerical Renormalization-Group Study
• Decoherence induced by interacting quantum spin baths
• Quantum decoherence of a charge qubit in a spin-fermion model
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Cited by in corpus (6)

• Non-perturbative stochastic method for driven spin-boson model
• Driving Spin-Boson Models From Equilibrium Using Exact Quantum Dynamics
• The excitation operator approach to non-Markovian dynamics of quantum impurity models in the Kondo regime
• The Eccentric Collective BFKL Pomeron
• Steady Schrödinger cat state of a driven Ising chain
• Decoherence induced by an ordered environment