We consider the quantum quench in the XX spin chain starting from a tilted Néel state which explicitly breaks the $U(1)$ symmetry of the post-quench Hamiltonian. Very surprisingly, the $U(1)$ symmetry is not restored at large time because of the activation of a non-Abelian set of charges which all break it. The breaking of the symmetry can be effectively and quantitatively characterised by the recently introduced entanglement asymmetry. By a combination of exact calculations and quasi-particle picture arguments, we are able to exactly describe the behaviour of the asymmetry at any time after the quench. Furthermore we show that the stationary behaviour is completely captured by a non-Abelian generalised Gibbs ensemble. While our computations have been performed for a non-interacting spin chain, we expect similar results to hold for the integrable interacting case as well because of the presence of non-Abelian charges also in that case.
Cited by 1
Chen, RÃ©nyi negativities in non-equilibrium open free-boson chains
J. High Energ. Phys. 2023, 122 (2023) [Crossref]
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- 1 Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies [SISSA]
- 2 INFN Sezione di Trieste / INFN Trieste
- 3 California Institute of Technology [CalTech]
- 4 Walter Burke Institute for Theoretical Physics
- 5 Laboratoire de Probabilités, Statistique et Modélisation [LPSM]
- 6 Centro Internazionale di Fisica Teorica Abdus Salam / Abdus Salam International Centre for Theoretical Physics [ICTP]