False vacuum decay in the transverse field Ising model ‌on a quantum annealer

G. Humar,1,2 J. Vodeb,1,2,3 D. Mihailovic1,2,4

1Department of Complex Matter, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia

2Department of Physics, Faculty for Mathematics and Physics, Jadranska 19, University of Ljubljana, SI-1000 Ljubljana, Slovenia

3Institute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich, Wilhelm-7 Johnen-Straße, DE-52425 Jülich, Germany

4CENN Nanocenter, Jamova 39, SI-1000 Ljubljana, Slovenia

This presentation deals with using quantum annealing for observing false vacuum decay in the transverse field Ising model. False vacuum decay is one of the central ideas in quantum field theory. It describes a scenario where a system in a metastable false vacuum state transitions to the true vacuum state. The transition happens by creation of bubbles of true vacuum that expand over the whole system. The timescales and the dynamics of this phenomenon are difficult to observe and describe analytically. The process of transition is analogue to first order phase transitions in condensed matter physics. Metastable states with analogous dynamics can be observed on measurable timescales. An example of such a system is the transverse field Ising model, where false vacuum decay appears in nonequilibrium dynamics following a sudden change in the direction of the external field. Numerical studies have shown the existance of a set of parameters for which false vacuum decay can be observed. Transverse field Ising model is implemented in the D-Wave quantum annealer. Measurements on this device are used to simulate the dynamics of the transverse Ising model. In general, results of simulations show decay dynamics that do not match the theoretical description of the false vacuum decay exactly. This implies additions effects on the dynamics. In the specific limit of low transverse fields and high longitudinal fields the measured dynamics approach the theoretically expected dynamics. Possible explanations for the observed deviations include the open nature of the system in the quantum annealer, the slow change of the field direction and poor validity of the approximations used for theoretical predictions for magnitudes of fields used in the simulations.

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