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arXiv · 2601.09563

Lattice fermion simulation of spontaneous time-reversal symmetry breaking in a helical Luttinger liquid

V. A. Zakharov·J. Sánchez Fernán·C. W. J. Beenakker
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Abstract

We extend a recently developed "tangent fermion" method to discretize the Hamiltonian of a helical Luttinger liquid on a one-dimensional lattice, including two-particle backscattering processes that may open a gap in the spectrum. The fermion-doubling obstruction of the sine dispersion is avoided by working with a tangent dispersion, preserving the time-reversal symmetry of the Hamiltonian. The numerical results from a tensor network calculation on a finite lattice confirm the expectation from infinite-system analytics, that a gapped phase with spontaneously broken time-reversal symmetry emerges when the Fermi level is tuned to the Dirac point and the Luttinger parameter crosses a critical value.

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V. A. Zakharov, J. Sánchez Fernán, C. W. J. Beenakker. 2026-01-14. Lattice fermion simulation of spontaneous time-reversal symmetry breaking in a helical Luttinger liquid. https://doi.org/10.1002/andp.202600004

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