Entanglement scaling at first order phase transitions

TL;DR

This paper demonstrates that finite size scaling of entanglement measures can reliably distinguish between first and second order quantum phase transitions near multicritical points, resolving ambiguities caused by finite system sizes.

Contribution

It introduces a method to apply finite size scaling to entanglement measures to correctly identify the order of quantum phase transitions near multicritical points.

Findings

Finite size scaling of entanglement distinguishes transition types.

Method resolves ambiguities near multicritical points.

Entanglement measures show clear signatures of transition order.

Abstract

First order quantum phase transitions (1QPTs) are signaled, in the thermodynamic limit, by discontinuous changes in the ground state properties. These discontinuities affect expectation values of observables, including spatial correlations. When a 1QPT is crossed in the vicinity of a second order one (2QPT), due to the correlation length divergence of the latter, the corresponding ground state is modified and it becomes increasingly difficult to determine the order of the transition when the size of the system is finite. Here we show that, in such situations, it is possible to apply finite size scaling to entanglement measures, as it has recently been done for the order parameters and the energy gap, in order to recover the correct thermodynamic limit. Such a finite size scaling can unambigously discriminate between first and second order phase transitions in the vicinity of multricritical points even when the singularities displayed by entanglement measures lead to controversial results.