2010/04/13 by Kazutaka Takahashi, Yoshiki Matsuda · 1 citation
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum many-body systems #Theoretical and Computational Physics #cond-mat.dis-nn
paper · pdf · doi:10.1088/1742-6596/233/1/012008
published as J. Phys.: Conf. Ser. 233, 012008 (2010) · 10 pages, 8 figures, Proceedings of the IW-SMI2010
arxiv created 2010/04/13 · openalex publication_date 2010/06/01 · arxiv updated 2010/07/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
We study for random quantum spin systems the energy gap between the ground and first excited states to clarify a relation to the spin-glass-paramagnetic phase transition. We find that for the transverse Sherrington-Kirkpatrick model the vanishing of the averaged gap does not identify the transition. A power-law form of the gap distribution function leads to power-law distributions of the linear, spin-glass, and nonlinear susceptibilities. They diverge at different points, which we attribute to a quantum "Griffiths" mechanism. On the other hand, the classical treatment is justified for the transverse random energy model and the phase transition can be found by a sudden change of the ground state.