Decoherence dynamics of interacting qubits coupled to a bath of local optical phonons

TL;DR

This paper investigates how local optical phonons affect decoherence in an interacting qubit system modeled by the IRHM, revealing that certain quantum coherences are preserved despite strong spin-phonon coupling.

Contribution

The study derives an effective Hamiltonian in the polaron frame that commutes with IRHM, demonstrating preserved eigenstates and coherence under strong coupling conditions.

Findings

Off-diagonal density matrix elements do not decay in the IRHM eigenbasis.

Effective Hamiltonian shares eigenstates with IRHM under strong coupling.

Decoherence effects are suppressed in the studied regime.

Abstract

We study decoherence in an interacting qubit system described by infinite range Heisenberg model (IRHM) in a situation where the system is coupled to a bath of local optical phonons. Using perturbation theory in polaron frame of reference, we derive an effective Hamiltonian that is valid in the regime of strong spin-phonon coupling under non-adiabatic conditions. It is shown that the effective Hamiltonian commutes with the IRHM upto leading orders of perturbation and thus has the same eigenstates as the IRHM. Using a quantum master equation with Markovian approximation of dynamical evolution, we show that the off diagonal elements of the density matrix donot decay in the energy eigen basis of IRHM.