Topological Excitations near the Local Critical Point in the Dissipative 2D XY model

TL;DR

This paper investigates the critical behavior of the dissipative 2D XY model, revealing how topological excitations called warps drive a quantum phase transition characterized by local spatial interactions and power-law temporal correlations.

Contribution

It introduces a new understanding of topological excitations called warps as monopole-anti-monopole configurations and their role in the quantum criticality of the dissipative 2D XY model.

Findings

Warps are monopole-anti-monopole configurations with zero total charge.

Warps interact locally in space but logarithmically in time.

Dissipation causes warps to unbind, leading to a quantum phase transition.

Abstract

The dissipative XY model in two spatial dimensions belongs to a new universality class of quantum critical phenomena with the remarkable property of the decoupling of the critical fluctuations in space and time. We have shown earlier that the quantum critical point is driven by proliferation in time of topological configurations that we termed warps. We show here that a warp may be regarded as a configuration of a monopoles surrounded symmetrically by anti-monopoles so that the total charge of the configuration is zero. Therefore the interaction with other warps is local in space. They however interact with other warps at the same spatial point logarithmically in time. As a function of dissipation warps unbind leading to a quantum phase transition. The critical fluctuations are momentum independent but have power law correlations in time.