Symmetry and symmetry breaking are two pillars of modern quantum physics. Still, quantifying how much a symmetry is broken is an issue that has received little attention. In extended quantum systems, this problem is intrinsically bound to the subsystem of interest. Hence, in this work, we borrow methods from the theory of entanglement in many-body quantum systems to introduce a subsystem measure of symmetry breaking that we dub entanglement asymmetry. As a prototypical illustration, we study the entanglement asymmetry in a quantum quench of a spin chain in which an initially broken global U(1) symmetry is restored dynamically. We adapt the quasiparticle picture for entanglement evolution to the analytic determination of the entanglement asymmetry. We find, expectedly, that larger is the subsystem, slower is the restoration, but also the counterintuitive result that more the symmetry is initially broken, faster it is restored, a sort of quantum Mpemba effect, a phenomenon that we show to occur in a large variety of systems.

Entanglement asymmetry as a probe of symmetry breaking / Ares, Filiberto; Murciano, Sara; Calabrese, Pasquale. - In: NATURE COMMUNICATIONS. - ISSN 2041-1723. - 14:1(2023), pp. 1-7. [10.1038/s41467-023-37747-8]

Entanglement asymmetry as a probe of symmetry breaking

Ares, Filiberto;Murciano, Sara;Calabrese, Pasquale
2023-01-01

Abstract

Symmetry and symmetry breaking are two pillars of modern quantum physics. Still, quantifying how much a symmetry is broken is an issue that has received little attention. In extended quantum systems, this problem is intrinsically bound to the subsystem of interest. Hence, in this work, we borrow methods from the theory of entanglement in many-body quantum systems to introduce a subsystem measure of symmetry breaking that we dub entanglement asymmetry. As a prototypical illustration, we study the entanglement asymmetry in a quantum quench of a spin chain in which an initially broken global U(1) symmetry is restored dynamically. We adapt the quasiparticle picture for entanglement evolution to the analytic determination of the entanglement asymmetry. We find, expectedly, that larger is the subsystem, slower is the restoration, but also the counterintuitive result that more the symmetry is initially broken, faster it is restored, a sort of quantum Mpemba effect, a phenomenon that we show to occur in a large variety of systems.
2023
14
1
1
7
2036
10.1007/JHEP06(2023)139
https://arxiv.org/abs/2304.09906
Ares, Filiberto; Murciano, Sara; Calabrese, Pasquale
File in questo prodotto:
File Dimensione Formato  
s41467-023-37747-8.pdf

non disponibili

Descrizione: pdf editoriale
Tipologia: Versione Editoriale (PDF)
Licenza: Creative commons
Dimensione 934.34 kB
Formato Adobe PDF
934.34 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/136490
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 41
  • ???jsp.display-item.citation.isi??? 38
social impact