Quantum many-body theory for electron spin decoherence in nanoscale nuclear spin baths

TL;DR

This paper reviews recent advances in quantum many-body theories for understanding electron spin decoherence caused by nanoscale nuclear spin baths, highlighting theoretical developments, experimental confirmations, and future challenges.

Contribution

It introduces a truncated cluster correlation expansion theory to accurately model many-body correlations in nuclear spin baths affecting electron spins.

Findings

Successfully predicted experimental results across various systems

Identified limitations of current quantum many-body theories

Discussed future directions for theory development

Abstract

Decoherence of electron spins in nanoscale systems is important to quantum technologies such as quantum information processing and magnetometry. It is also an ideal model problem for studying the crossover between quantum and classical phenomena. At low temperatures or in light-element materials where the spin-orbit coupling is weak, the phonon scattering in nanostructures is less important and the fluctuations of nuclear spins become the dominant decoherence mechanism for electron spins. Since 1950s, semiclassical noise theories have been developed for understanding electron spin decoherence. In spin-based solid-state quantum technologies, the relevant systems are in the nanometer scale and the nuclear spin baths are quantum objects which require a quantum description. Recently, quantum pictures have been established to understand the decoherence and quantum many-body theories have been developed to quantitatively describe this phenomenon. Anomalous quantum effects have been predicted and some have been experimentally confirmed. A systematically truncated cluster correlation expansion theory has been developed to account for the many-body correlations in nanoscale nuclear spin baths that are built up during the electron spin decoherence. The theory has successfully predicted and explained a number of experimental results in a wide range of physical systems. In this review, we will cover these recent progresses. The limitations of the present quantum many-body theories and possible directions for future development will also be discussed.