Exciton propagation via quantum walks based on non-Hermitian coin flip operations

TL;DR

This paper investigates exciton propagation modeled as a quantum walk with non-Hermitian coin operations, revealing effects of dissipation, non-Markovian dynamics, and topological features relevant to photosynthetic systems.

Contribution

It introduces a novel quantum walk framework with non-Hermitian coin flips to study exciton dynamics, incorporating dissipation and topological phenomena.

Findings

Probability distributions depend on system parameters.

Non-Markovian effects influence exciton propagation.

Exceptional points and topological defects are identifiable.

Abstract

We examine the coherent propagation of the one-dimensional Frenkel exciton (correlated electron-hole pair system) based on a model of a quantum walker in multi-dimensional Hilbert space. The walk is governed by a non-Hermitian coin flip operation coupled to a generalized shift process. The dissipative coin flip operation is associated with amplitude leakages at occupied sites, typical of processes which occur when an exciton is transferred along dimer sites in photosynthetic protein complexes. We analyze the characteristics probability distribution of the one-dimensional quantum walk for various system parameters, and examine the complex interplay between non-Markovian signatures and amplitude leakages within the Hilbert position subspace. The visibility of topological defects such as exceptional points, and non-Markovian signatures via quantum tomography based spectroscopic measurements are discussed.