Effect of random fluctuations on quantum spin-glass transitions at zero temperature

Abstract

We study the effects of random fluctuations on quantum phase transitions by the energy gap analysis. For the infinite-ranged spin-glass models with a transverse field, we find that a strong sample-to-sample fluctuation effect leads to broad distributions of the energy gap. As a result, the linear, spin-glass, and nonlinear susceptibilities behave differently from each other. The power-law tail of the distribution implies a quantum Griffiths-like effect that could be observed in various random quantum systems. We also discuss the mechanisms of the phase transition in terms of the energy gap by comparing the Sherrington-Kirkpatrick model and random energy model, which demonstrate the difference between the continuous and discontinuous phase transitions.

4 pages, 5 figures; fig.3 replaced, minor changes

References in corpus (3)

• Simple Glass Models and their Quantum Annealing
• Quantum fluctuations in the transverse Ising spin glass model: A field theory of random quantum spin systems
• Dynamical correlations in the Sherrington-Kirkpatrick model in a transverse field

Cited by in corpus (3)

• Pattern-recalling processes in quantum Hopfield networks far from saturation
• Effects of low-lying excitations on ground-state energy and energy gap of Sherrington-Kirkpatrick model in transverse field
• Effects of dynamical paths on the energy gap and the corrections to free energy in path integrals of mean-field quantum spin systems