Speaker
Description
This talk describes recent advances on entanglement out-of-equilibrium.
In the first part, I will focus on symmetry-resolved entanglement, which describes how entanglement is distributed among the symmetry sectors of a system. In this context, charged moments of the reduced density matrix provide a natural starting point. I will show how these quantities can be studied using Ballistic Fluctuation Theory [1], a framework that describes large-scale ballistic fluctuations of conserved charges and associated currents and, through the height-field formulation of twist fields, gives access to the asymptotic behaviour of their two-point correlation functions [2]. This approach provides a rigorous derivation of results previously obtained from the phenomenological quasiparticle picture of entanglement spreading after pair-producing quenches [3].
In the second part, I will turn to a different notion of bipartition, namely field-space entanglement. Rather than splitting a single system in real space, one may consider two coupled one-dimensional gapless systems and ask how entanglement develops between the two fields themselves. For systems described by Luttinger liquid theory, I will discuss the dynamics of logarithmic negativity and mutual information following coupling quenches, at zero and finite temperature [4]. In particular, we obtain exact analytical results for their large-time averages and are able to characterise the early-time growth of entanglement. This provides a framework to study both quantum entanglement and total correlations in out-of-equilibrium multi-field systems, with potential experimental relevance for coupled Bose–Einstein condensates [5].
[1] B. Doyon, J. Myers, Annales Henri Poincaré (2019)
[2] G. Li, L. Dupays, P. Ruggiero, arXiv (2026)
[3] P. Calabrese, J. Cardy, J. Stat. Mech. (2005)
[4] L. Dupays, T. Murthado, B-H. Tiang, N. Ng, P. Ruggiero, to appear (2026)
[5] V. Gritsev, A. Polkovnikov, E. Demler, Phys. Rev. B (2007)