Quantum vs. Classical Spin: A Comparative Study of Dipolar Spin Dynamics and the Onset of Chaos

TL;DR

This study compares quantum and classical dipolar spin dynamics, revealing significant differences in their behavior over time and highlighting fundamental distinctions between the two descriptions.

Contribution

It provides a direct comparison between quantum and classical spin simulations, emphasizing the limitations of classical models in capturing quantum spin dynamics.

Findings

Classical and quantum spin dynamics differ significantly over time.

Discrepancies are evident at both short and long timescales.

Fundamental differences in descriptions explain the observed discrepancies.

Abstract

We investigate the spin dynamics of a dipole-coupled system by comparing a direct solution of the Schrodinger equation for quantum spins with simulations of classical spins. Although classical spins have long been used in microscopic spin dynamics simulations, we demonstrate that their results differ significantly from those of quantum spins. Using Free Induction Decay as a benchmark, we find that while the overall patterns are qualitatively similar, significant discrepancies emerge at both short and long timescales. We trace these differences to fundamental distinctions in the two descriptions.