A perturbative non-Markovian treatment to low-temperature spin decoherence

TL;DR

This paper introduces a non-Markovian master equation approach to predict low-temperature spin decoherence in molecular qubits, linking electronic structure to decoherence dynamics with good experimental agreement.

Contribution

It develops a novel non-Markovian theoretical framework that directly relates ab initio electronic parameters to decoherence in molecular spins at low temperatures.

Findings

Good agreement with experimental relaxation data

Provides a computationally efficient prediction method

Accounts for pure dephasing in low-temperature regimes

Abstract

Molecular spins are promising candidates for quantum information science, leveraging coherent electronic spin states for quantum sensing and computation. However, the practical application of these systems is hindered by electronic spin decoherence, driven by interactions with nuclear spins in the molecule and the surrounding environment at low temperatures. Predicting dephasing dynamics remains a formidable challenge due to the complexity of the spin bath. In this work, we develop a non-Markovian time-convolutionless master equation to treat an electronic spin coupled to a nuclear-spin bath. By relating ab initio electronic structure parameters directly to the decoherence dynamics, we provide a framework that accounts for pure dephasing in the low-temperature limit. We apply this method to a series of molecular qubit candidates and demonstrate good agreement with experimental relaxation trends. This approach offers a computationally efficient path for the prediction of low-temperature decoherence trends in molecular spin systems.