Entanglement of systems of dipolar coupled nuclear spins at the adiabatic demagnetization

TL;DR

This paper investigates how adiabatic demagnetization induces entanglement in dipolar-coupled nuclear spin systems, revealing that entanglement occurs at microkelvin temperatures nearly independent of system size or dimension.

Contribution

It provides numerical analysis of entanglement emergence during ADRF in small nuclear spin systems, highlighting size and dimension effects on entanglement temperatures.

Findings

Entanglement occurs at microkelvin temperatures.

Temperature of entanglement is nearly independent of system size.

Weak dependence of entanglement temperature on system dimension.

Abstract

We consider the adiabatic demagnetization in the rotating reference frame (ADRF) of a system of dipolar coupled nuclear spins $s=1/2$ in the external magnetic field. The demagnetization starts with the offset of the external magnetic field (in frequency units) from the Larmor frequency being several times greater than the local dipolar field. For different subsystem sizes, we have found from numerical simulations the temperatures at which subsystems of a one-dimensional nine-spin chain and a plane nine-spin cluster become entangled. These temperatures are of the order of microkelvins and are almost independent of the subsystem size. There is a weak dependence of the temperature on the space dimension of the system.