Experimental characterization of coherent magnetization transport in a one-dimensional spin system

TL;DR

This paper experimentally investigates room-temperature magnetization transport in a one-dimensional spin chain, revealing slow multi-spin correlation growth and confirming theoretical models with high accuracy, and estimating the group velocity of magnetization.

Contribution

It provides the first experimental characterization of magnetization dynamics under a double-quantum Hamiltonian in a 1D spin system, confirming theoretical predictions and extending understanding of quantum transport.

Findings

Magnetization and two-spin correlations evolve 90 degrees out of phase.

Transport dynamics are confined to a Liouville space of dimension scaling as N^2.

Group velocity of magnetization is approximately 6.04 um/s.

Abstract

We experimentally characterize the non-equilibrium, room-temperature magnetization dynamics of a spin chain evolving under an effective double-quantum Hamiltonian. We show that the Liouville space operators corresponding to the magnetization and the two-spin correlations evolve 90 degrees out of phase with each other, and drive the transport dynamics. For a nearest-neighbor-coupled N-spin chain, the dynamics are found to be restricted to a Liouville operator space whose dimension scales only as N^2, leading to a slow growth of multi-spin correlations. Even though long-range couplings are present in the real system, we find excellent agreement between the analytical predictions and our experimental results, confirming that leakage out of the restricted Liouville space is slow on the timescales investigated. Our results indicate that the group velocity of the magnetization is 6.04 +/- 0.38 um/s, corresponding to a coherent transport over N ~ 26 spins on the experimental timescale. As the double-quantum Hamiltonian is related to the standard one-dimensional XX Hamiltonian by a similarity transform, our results can be directly extended to XX quantum spin chains, which have been extensively studied in the context of both quantum magnetism and quantum information processing.