Quantifying and Controlling Entanglement in the Quantum Magnet Cs 2

Autor: Pontus Laurell, Zbigniew Tylczyński, Gonzalo Alvarez, Allen Scheie, D. Alan Tennant, Satoshi Okamoto, M. Enderle, Chiron J. Mukherjee, Michael Marek Koza, Radu Coldea
Rok vydání: 2021
Předmět:
Zdroj: Physical Review Letters
ISSN: 0031-9007
DOI: 10.1103/physrevlett.127.037201
Popis: The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using inelastic neutron scattering (INS) to implement a model-independent measurement protocol for entanglement based on three entanglement witnesses: one-tangle, two-tangle, and quantum Fisher information (QFI). We perform high-resolution INS measurements on ${\mathrm{Cs}}_{2}{\mathrm{CoCl}}_{4}$, a close realization of the $S=1/2$ transverse-field $XXZ$ spin chain, where we can control entanglement using the magnetic field, and compare with density-matrix renormalization group calculations for validation. The three witnesses allow us to infer entanglement properties and make deductions about the quantum state in the material. We find QFI to be a particularly robust experimental probe of entanglement, whereas the one and two-tangles require more careful analysis. Our results lay the foundation for a general entanglement detection protocol for quantum spin systems.
Databáze: OpenAIRE