Statistical mechanics

Quantum phase transition induced by topological frustration

In quantum many-body systems with local interactions, the effects of boundary conditions are considered to be negligible, at least for sufficiently large systems. Here we show an example of the opposite. We consider a spin chain with two competing …

Resilience of the topological phases to frustration

Recently it was highlighted that one-dimensional antiferromagnetic spin models with frustrated boundary conditions, i.e. periodic boundary conditions in a ring with an odd number of elements, may show very peculiar behavior. Indeed the presence of …

Effects of defects in the XY chain with frustrated boundary conditions

It has been recently proven that new types of bulk local order can ensue due to frustrated boundary condition, that is, periodic boundary conditions with an odd number of lattice sites and antiferromagnetic interactions. For the quantum XY chain in …

Asymptotic behavior of Toeplitz determinants with a delta function singularity

We find the asymptotic behaviors of Toeplitz determinants with symbols which are a sum of two contributions, one analytical and non-zero function in an annulus around the unit circle, and the other proportional to a Dirac delta function. The formulas …

Mutual information for fermionic systems

We study the behavior of the mutual information (MI) in various quadratic fermionic chains, with and without pairing terms and both with short- and long-range hoppings. The models considered include the short-range Kitaev model and also cases in …

The frustration of being odd: how boundary conditions can destroy local order

A central tenant in the classification of phases is that boundary conditions cannot affect the bulk properties of a system. In this work, we show striking, yet puzzling, evidence of a clear violation of this assumption. We use the prototypical …

The frustration of being odd: universal area law violation in local systems

At the core of every frustrated system, one can identify the existence of frustrated rings that are usually interpreted in terms of single–particle physics. We check this point of view through a careful analysis of the entanglement entropy of both …

n-cluster models in a transverse magnetic field

We analyze a family of 1D fully analytically solvable models in which a many-body cluster interaction, acting simulatenously on n  +  2 spins, competes with a uniform transverse external field. These models can be solved analytically using the …

Hydrodynamics of local excitations after an interaction quench in 1D cold atomic gases

We discuss the hydrodynamic approach to the study of the time evolution—induced by a quench—of local excitations in one dimension. We focus on interaction quenches, the considered protocol consists of creating a stable localized excitation …