Experimental detection of quantum information sharing and their quantification in quantum spin systems

TL;DR

This study experimentally investigates macroscopic entanglement in a quantum spin chain through magnetic susceptibility and magnetization, demonstrating quantum phase transitions and information sharing, with results aligning well with theoretical predictions.

Contribution

It introduces a method to detect and quantify entanglement in spin systems using macroscopic magnetic measurements, linking quantum information tools with experimental condensed matter physics.

Findings

Entanglement can be extracted from susceptibility data.

Quantum phase transition is observable via macroscopic measurements.

Experimental results agree with theoretical models across various conditions.

Abstract

We study the macroscopic entanglement properties of a low dimensional quantum spin system by investigating its magnetic properties at low temperatures and high magnetic fields. The tempera- ture and magnetic field dependence of entanglement from the susceptibility and magnetization data comparing the experimental extraction with theoretical estimates are given. Extraction of entan- glement has been made possible through the macroscopic witness operators magnetic susceptibility. The protocol followed in doing so has been outlined in some recent work. Various plots of entan- glement comparing the experimental extraction with theoretical estimates are given. Quantitative comparison between concurrence and entanglement witness is given for both the theoretical and experimental results. Theory and experiments match over a wide range of temperature and field. The spin system studied is a chain, which exhibits dimerisation and yields fascinating entanglement properties when the temperature and magnetic field is varied. These spin systems exhibit quantum phase transition (QPT) at low temperatures, when the magnetic field is swept through a critical value. We show explicitly for the first time, using tools used in quantum information processing (QIP), that quantum phase transition (QPT) can be captured experimentally using canonically conjugate observables. Macroscopically, quantum complementarity relation clearly delineates entangled states from separable states across the QPT. We have estimated the partial information sharing in this system from our magnetization and susceptibility data. The complementarity relation has been experimentally verified to hold in this system