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Quantum transitions driven by one-bond defects in quantum Ising rings

Massimo Campostrini¹, Andrea Pelissetto², and Ettore Vicari¹

¹Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
²Dipartimento di Fisica di “Sapienza” Università di Roma and INFN, Sezione di Roma I, I-00185 Roma, Italy

Phys. Rev. E 91, 042123 – Published 20 April, 2015

DOI: https://doi.org/10.1103/PhysRevE.91.042123

Abstract

We investigate quantum scaling phenomena driven by lower-dimensional defects in quantum Ising-like models. We consider quantum Ising rings in the presence of a bond defect. In the ordered phase, the system undergoes a quantum transition driven by the bond defect between a magnet phase, in which the gap decreases exponentially with increasing size, and a kink phase, in which the gap decreases instead with a power of the size. Close to the transition, the system shows a universal scaling behavior, which we characterize by computing, either analytically or numerically, scaling functions for the low-level energy differences and the two-point correlation function. We discuss the implications of these results for the nonequilibrium dynamics in the presence of a slowly varying parallel magnetic field $h$ , when going across the first-order quantum transition at $h = 0$ .

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References (33)

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Quantum transitions driven by one-bond defects in quantum Ising rings

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