In this paper we investigate an entanglement measure, the R\'enyi entropy, in a 1+1D integrable quantum field theory known as the Federbush model. This is a deformation of the theory of two massive Dirac fermions by means of a bilinear term in the $U(1)$ currents that couples the two fermion species. This deformation gives rise to $S$-matrix elements which are coupling-dependent phases, distinct from $- 1$. These non-trivial phases can be seen as encoding anyon-like statistics. From this viewpoint, the Federbush model is a toy model for topological features of entanglement in one space dimension. In this paper we show that, for an infinite system, these topological features play no role when computing many known measures of entanglement at equilibrium in the ground state. This conclusion applies also to the post-quench dynamics after a small quench of the topological parameter.
Emmalise J. H. Aalbers, O. Castro-Alvaredo· 0 citations
We investigate the subsystem entanglement asymmetry in random quantum automaton ensembles, which are generated by permuting the basis states in the Hilbert space and applying global phase shifts. We compute the ensemble average of the $U(1)$ subsystem asymmetry in different connectivity geometries, showing that the late-time limit of the ensemble associated to a 2-local circuit geometry coincides with the all-to-all ensemble average. By focusing on different subsystem sizes, we demonstrate that, similarly to Haar-random circuits, the system locally symmetrizes. However, in sharp contrast to the Haar-random setting, the scale at which symmetrization happens depends on the initial state, a phenomenon we associate with the interplay of conservation of the participation entropy and the uniform exploration of charge sectors. Additionally, we connect the growth of the subsystem asymmetry to the subsystem coherence and show that their growth is characterized by the same symmetrization scale.
O. Castro-Alvaredo, Dávid Szász-Schagrin, Michele Mazzoni· 2 citations
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