Bonn 2025 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 63: Poster – Quantum Information (joint session QI/Q)

Q 63.41: Poster

Thursday, March 13, 2025, 17:00–19:00, Tent

Quantum robustness of the toric code in a parallel field on the honeycomb lattice — •Viktor Kott, Matthias Mühlhauser, Jan Alexander Koziol, and Kai Phillip Schmidt — Chair of Theoretical Physics V, Friedrich-Alexander-Universität, Erlangen, Germany

We study the quantum robustness of topological order in the toric code on a honeycomb lattice under a uniform parallel field. For a field in the z-direction, the system maps to the transverse-field Ising model on the honeycomb lattice, showing a second-order quantum phase transition in the 3D Ising* universality class. A positive x-field similarly maps to a ferromagnetic transverse-field Ising model on the triangular lattice, with the same phase transition. In contrast, a negative x-field maps to a frustrated antiferromagnetic model, leading to a 3D XY* transition and a first-order transition to a polarized phase at higher field values. These findings, confirmed by quantum Monte Carlo and series expansions, apply to both honeycomb and triangular lattices, revealing critical behaviors and potential multi-critical points.

Keywords: toric code; topological order; series expansion; quantum monte carlo; stochastic series expansion