Mesoscopic Phase Coherence in a Quantum Spin Fluid

TL;DR

This paper demonstrates that mesoscopic quantum phase coherence in a one-dimensional spin chain can be monitored and manipulated using magnetic neutron scattering, revealing a coherence length significantly larger than classical correlations.

Contribution

It shows how quantum coherence length in a spin fluid can be measured and controlled, advancing understanding of quantum coherence in low-dimensional systems.

Findings

Quantum coherence length is approximately 20 nm in Y2BaNiO5.

Coherence length can be altered by static and thermal defects.

Quantum coherence exceeds classical correlation lengths by nearly an order of magnitude.

Abstract

Mesoscopic quantum phase coherence is important because it improves the prospects for handling quantum degrees of freedom in technology. Here we show that the development of such coherence can be monitored using magnetic neutron scattering from a one-dimensional spin chain Y2BaNiO5, a quantum spin fluid where no classical, static magnetic order is present. In the cleanest samples, the quantum coherence length is 20 nm, almost an order of magnitude larger than the classical antiferromagnetic correlation length of 3 nm. We also demonstrate that the coherence length can be modified by static and thermally activated defects in a quantitatively predictable manner.