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Related Experiment Video

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Generation and Coherent Control of Pulsed Quantum Frequency Combs

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Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled XY Models.

Giacomo Bighin¹, Nicolò Defenu², István Nándori^3,4,5

¹IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria.

Physical Review Letters

|October 2, 2019

Summary

Coupling two-dimensional systems with topological Berezinskii-Kosterlitz-Thouless (BKT) transitions reveals a new BKT-paired phase. This phase exhibits unique correlations, persisting even with finite interlayer coupling.

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Area of Science:

Condensed matter physics
Topological phases of matter
Statistical mechanics

Background:

Two-dimensional systems can exhibit the Berezinskii-Kosterlitz-Thouless (BKT) transition.
In the uncoupled limit, these systems display distinct phases characterized by algebraic or exponential decay of correlation functions.

Purpose of the Study:

Investigate the impact of linear tunneling coupling on systems exhibiting BKT transitions.
Identify emergent phases and their correlation properties under coupling.
Map the phase diagram of coupled topological systems.

Main Methods:

Theoretical analysis of linear tunneling coupling between two-dimensional systems.
Numerical simulations of two coupled XY models at finite temperatures.
Renormalization group approach to characterize the phase diagram.

Main Results:

A novel BKT-paired phase emerges when linear coupling is introduced.
This phase is characterized by exponentially decaying one-body correlations and power-law decaying two-body correlations.
Numerical evidence confirms the presence of the BKT-paired phase for any finite interlayer coupling.

Conclusions:

Linear coupling between BKT systems can lead to new topological phases.
The BKT-paired phase represents a distinct state of matter with unique correlation behaviors.
The findings provide a comprehensive understanding of phase transitions in coupled topological systems.