Scaling Theories of Kosterlitz-Thouless Phase Transitions

TL;DR

This paper develops and tests scaling theories for Kosterlitz-Thouless phase transitions, focusing on correlation length growth, finite-size effects, and defect dynamics, validated through numerical simulations of the 1D Bose-Hubbard model.

Contribution

It introduces new scaling forms for KT transitions considering finite entanglement and time effects, and verifies them with numerical simulations of the Bose-Hubbard model.

Findings

Scaling theories accurately describe numerical results.

Critical point estimated at 0.302(1).

Finite-entanglement and finite-time scaling forms are validated.

Abstract

We propose scaling theories for Kosterlitz-Thouless (KT) phase transitions on the basis of the hallmark exponential growth of their correlation length. Finite-size scaling, finite-entanglement scaling, short-time critical dynamics, and finite-time scaling, as well as some of their combinations are studied. Relaxation times of both a usual power-law and an unusual power-law with a logarithmic factor are considered. Finite-size and finite-entanglement scaling forms somehow similar to a frequently employed ansatz are presented. The Kibble-Zurek scaling of topological defect density for a linear driving across the KT transition point is investigated in detail. An implicit equation for a rate exponent in the theory is derived and the exponent varies with the distance from the critical point and the driving rate consistent with relevant experiments. To verify the theories, we utilize the KT phase transition of a one-dimensional Bose-Hubbard model. The infinite time-evolving-block-decimation algorithm is employed to solve numerically the model for finite bond dimensions. Both a correlation length and an entanglement entropy in imaginary time and only the entanglement entropy in real-time driving are computed. Both the short-time critical dynamics in imaginary time and the finite-time scaling in real-time driving, both including the finite bond dimension, for the measured quantities are found to describe the numerical results quite well via surface collapses. The critical point is also estimated and confirmed to be $0.302(1)$ at the infinite bond dimension on the basis of the scaling form.