Polaron dynamics and decoherence in an interacting two-spin system coupled to optical phonon environment

Abstract

We study two anisotropically interacting spins coupled to optical phonons; we restrict our analysis to the regime of strong coupling to the environment, to the antiadiabatic region, and to the subspace with zero value for $S_T^z$ (the z-component of the total spin). In the case where each spin is coupled to a different phonon bath, we assume that the system and the environment are initially uncorrelated (and form a simply separable state) in the polaronic frame of reference. By analyzing the {polaron} dynamics through non-Markovian quantum master equation, we find that the system manifests a small amount of decoherence that decreases both with increasing non-adiabaticity and with enhancing strength of coupling; whereas, under the Markovian approximation, the polaronic system exhibits a decoherence free behavior. For the situation where both spins are coupled to the same phonon bath, we also show that the system is decoherence free in the subspace where $S_T^z$ is fixed. To suppress decoherence through quantum control, we employ a train of pi pulses and demonstrate that unitary evolution of the system can be retained. We propose realization of a weakly decohering charge qubit from an electron in an oxide-based (tunnel-coupled) double quantum dot system.

Accepted in Phys. Rev. B. A new oxide-based charge qubit is proposed

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Cited by in corpus (3)

• Real-time decay of a highly excited charge carrier in the one-dimensional Holstein model
• Matrix-product-state method with a dynamical local basis optimization for bosonic systems out of equilibrium
• Study of decoherence in models for hard-core bosons coupled to optical phonons