Southwest Quantum Information and Technology

Instantons in thermally-assisted tunneling and quantum Monte Carlo simulations

Presenting Author: Zhang Jiang, (NASA Ames)
Contributing Author(s): Vadim N. Smelyanskiy, Sergio Boixo, Sergei V. Isakov, Guglielmo Mazzola, Matthias Troyer, and Hartmut Neven

Despite the big body of literature in spin tunneling, it has only been studied, using path integrals, in systems with fixed total spin. We introduce a non-perturbative spin path-integral instanton calculus for systems where, due to thermal fluctuations, the total spin is not preserved. We demonstrate in a closed analytical form of the scaling equivalence between the transition rate of quantum Monte Carlo, and the quantum tunneling rate when the later is dominated by the most probable path (an instanton). Our analytical results are confirmed by detailed numerical studies.

(Session 10 : Saturday from 9:15 am - 9:45 am)