Speaker
Description
The problem of closed, many-body quantum dynamics is, in general, an exceedingly difficult one. On the one hand, the entanglement entropy became recognised around the turn of the century as a suitable proxy for the relaxation of local subsystems in the closed many-body setting. On the other, the densities of quasiparticles have since become widely used to characterise the dynamics of local observables in integrable systems at the coarse-grained level: the generalised hydrodynamic picture. In light of these points, a huge step forward was to realise that the correlations between these quasiparticles offer an effective description for the entanglement generated by a quantum quench. The resulting quasiparticle picture for entanglement growth has enjoyed remarkable success in a wide variety of settings, and has also been shown to be applicable to other measures of the Schmidt spectrum such as the negativity and entanglement asymmetry – and even beyond. In this talk I will outline the basic quasiparticle formulation of these measures and review some of its main extensions: crucial to this story will be the ‘generalised’ quasiparticle picture that we formalised in our first work [1], which accommodates both higher mode correlation structures and higher spatial dimensions. I will also touch on cases in which the picture breaks down, with emphasis on the discrete symmetry breaking considered in our second work [2].
[1] Gibbins, M. et al. Quench dynamics in lattices above one dimension: The free fermionic case. Phys. Rev. B 109, 224310 (2024)
[2] Gibbins, M. et al. Translation symmetry restoration in integrable systems: The noninteracting case. Phys. Rev. B 112, L180307 (2025)