Adiabatic demagnetization and generation of entanglement in spin systems

TL;DR

This paper investigates how entanglement emerges in dipolar-coupled nuclear spin systems cooled via adiabatic demagnetization, revealing complex temperature and magnetic field dependencies and unexpected entanglement behaviors.

Contribution

It uncovers novel entanglement phenomena in spin chains, including two distinct regions of entanglement and complex magnetic field dependence, advancing understanding of quantum correlations in such systems.

Findings

Entanglement appears in two separate temperature and magnetic field regions.

The magnetic field dependence of concurrence can have two maxima.

Entangled states are observed for next- and next-next-neighbor spins.

Abstract

We study the entanglement emergence in a dipolar-coupled nuclear spin-1/2 system cooled using the adiabatic demagnetization technique. The unexpected behavior of entanglement for the next- and next-next-neighbor spins is revealed: entangled states of a spin system appear in two distinct temperature and magnetic field regions separated by a zero-concurrence area. The magnetic field dependence of the concurrence can have two maximums which positions are determined by the initial conditions and number of spins in a chain.