Decoherence dynamics in a polaron system with collective dephasing

Abstract

Within quantum information frameworks, managing decoherence stands as a pivotal task. The present work delves into decoherence dynamics of a dressed qubit, represented by a spinless fermion hopping between two lattice sites that are strongly coupled to a collective bosonic bath. To simplify calculations under strong coupling, we adopt the Lang-Firsov transformation, effectively minimizing system-bath interactions. Within the polaron perspective using Ohmic bath spectral density with a Gaussian cutoff, we identify a fundamental timescale $s$ (equivalently a length scale $l$), dictating coherence decay. Utilizing a quantum master equation in the energy eigen basis while maintaining fixed particle number, we demonstrate that coherence persists for small $s$ values but diminishes for larger ones. Additionally, we explore the utilization of $\pi$-pulses to manipulate decoherence within the system.