Interaction-induced topological phase transition at finite temperature

TL;DR

This paper reveals a finite-temperature topological phase transition in an interacting quantum system, driven by defects that localize zero modes, detectable via a non-local order parameter without thermodynamic signatures.

Contribution

It demonstrates a novel finite-temperature topological transition in an interacting model, characterized by a non-local order parameter and defect-driven mechanisms, expanding understanding beyond zero-temperature cases.

Findings

Finite-temperature topological transition exists in an interacting model.

Transition driven by defects enabling topological zero modes.

Order parameter vanishes at a critical temperature due to defect proliferation.

Abstract

We demonstrate the existence of topological phase transitions in interacting, symmetry-protected quantum matter at finite temperatures. Using a combined numerical and analytical approach, we study a one-dimensional Su-Schrieffer-Heeger model with added Hubbard interactions, where no thermodynamic phase transition occurs at finite temperatures. The transition is signalled by a quantized, non-local bulk topological order parameter. It is driven by defects, which are enabled by the combination of interaction and thermal activation, with no counterpart in the non-interacting limit. The defects localize topological zero modes, which, when sufficiently abundant, cause the order parameter to vanish. This phenomenon, interpreted via bulk-boundary correspondence, reflects the loss of a topological edge mode at a well-defined critical temperature in the thermodynamic limit. Unlike zero-temperature topological transitions, these finite-temperature transitions lack thermodynamic signatures but remain observable in controlled quantum systems, such as ultracold fermionic atoms in optical lattices.