False vacuum decay in quantum spin chains

TL;DR

This paper demonstrates that false vacuum decay, a phenomenon important in cosmology and particle physics, can be experimentally simulated using quantum spin chains, revealing decay dynamics and rates in accessible optical experiments.

Contribution

It shows that false vacuum decay can be studied in quantum spin chains with confinement, bridging theoretical physics and experimental quantum simulation.

Findings

Decay rate is exponentially small in the inverse of the longitudinal field.

Real-time evolution matches theoretical predictions.

Quantum simulators can observe false vacuum decay phenomena.

Abstract

The false vacuum decay has been a central theme in physics for half a century with applications to cosmology and to the theory of fundamental interactions. This fascinating phenomenon is even more intriguing when combined with the confinement of elementary particles. Due to the astronomical time scales involved, the research has so far focused on theoretical aspects of this decay. The purpose of this Letter is to show that the false vacuum decay is accessible to current optical experiments as quantum analog simulators of spin chains with confinement of the elementary excitations, which mimic the high energy phenomenology but in one spatial dimension. We study the non-equilibrium dynamics of the false vacuum in a quantum Ising chain and in an XXZ ladder. The false vacuum is the metastable state that arises in the ferromagnetic phase of the model when the symmetry is explicitly broken by a longitudinal field. This state decays through the formation of "bubbles" of true vacuum. Using iTEBD simulations, we are able to study the real-time evolution in the thermodynamic limit and measure the decay rate of local observables. We find that the numerical results agree with the theoretical prediction that the decay rate is exponentially small in the inverse of the longitudinal field.