Quantum spin helices more stable than the ground state: onset of helical protection

• URL: http://arxiv.org/abs/2302.02603v2
• Date: Tue, 28 Feb 2023 16:52:34 GMT
• Title: Quantum spin helices more stable than the ground state: onset of helical protection
• Authors: Stefan K\"uhn, Felix Gerken, Lena Funcke, Tobias Hartung, Paolo Stornati, Karl Jansen, Thore Posske
• Abstract summary: Topological magnetic structures are promising candidates for resilient information storage. We numerically implement the Schr"odinger equation and time-dependent perturbation theory for spin chains with fluctuating local magnetic fields. We find two classes of quantum spin helices that can reach and even exceed ground-state stability.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Topological magnetic structures are promising candidates for resilient information storage. An elementary example are spin helices in one-dimensional easy-plane quantum magnets. To quantify their stability, we numerically implement the stochastic Schr\"odinger equation and time-dependent perturbation theory for spin chains with fluctuating local magnetic fields. We find two classes of quantum spin helices that can reach and even exceed ground-state stability: Spin-current-maximizing helices and, for fine-tuned boundary conditions, the recently discovered "phantom helices". Beyond that, we show that the helicity itself (left- or right-rotating) is even more stable. We explain these findings by separated helical sectors and connect them to topological sectors in continuous spin systems. The resulting helical protection mechanism is a promising phenomenon towards stabilizing helical quantum structures, e.g., in ultracold atoms and solid state systems. We also identify an - up to our knowledge - previously unknown new type of phantom helices.

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