Quantum simulation of the early universe with a BEC

Esteban Calzetta, B. L. Hu

Benjamin D. Skuse

The early universe has been mimicked in the lab using a ring-shaped Bose–Einstein condensate (BEC) of ultracold atoms.

Bogdan Opanchuk, Rodney Polkinghorne, Oleksandr Fialko +2 more

A procedure is described whereby a linearly coupled spinor Bose condensate can be used as a physically accessible quantum simulator of the early universe. In particular, an experiment to generate an analog of an unstable vacuum in a relativistic scalar field theory is proposed. This is related to quantum theories of the inflationary phase of the early universe. There is an unstable vacuum sector whose dynamics correspond to the quantum sine‐Gordon equations in one, two or three space dimensions. Numerical simulations of the expected behavior are reported using a truncated Wigner phase‐space method, giving evidence for the dynamical formation of complex spatial clusters. Preliminary results showing the dependence on coupling strength, condensate size and dimensionality are obtained.

Vijayashankar Ramareddy, G. Behinaein, Peyman Ahmadi +1 more

King Lun Ng, Bogdan Opanchuk, Manushan Thenabadu +2 more

Despite being at the heart of the theory of the "Big Bang" and cosmic inflation, the quantum-field-theory prediction of false vacuum tunneling has not been tested.To address the exponential complexity of the problem, a table-top quantum simulator in the form of an engineered Bose-Einstein condensate (BEC) has been proposed to give dynamical solutions of the quantum-field equations.In this paper, we give a numerical feasibility study of the BEC quantum simulator under realistic conditions and temperatures, with an approximate truncated Wigner phase-space method.We report the observation of false vacuum tunneling in these simulations, and the formation of multiple bubble "universes" with distinct topological properties.The tunneling gives a transition of the relative phase of coupled Bose fields from a metastable to a stable "vacuum."We include finite-temperature effects that would be found in a laboratory experiment and also analyze the cutoff dependence of modulational instabilities in Floquet space.Our numerical phase-space model does not use thin-wall approximations, which are inapplicable to cosmologically interesting models.It is expected to give the correct quantum treatment, including superpositions and entanglement during dynamics.By analyzing a nonlocal observable called the topological phase entropy (TPE), our simulations provide information about phase structure in the true vacuum.We observe a cooperative effect in which true vacua bubbles representing distinct universes each have one or the other of two distinct topologies.The TPE initially increases with time, reaching a peak as multiple universes are formed, and then decreases with time to the phase-ordered vacuum state.This gives a model for the formation of universes with one of two distinct phases, which is a possible solution to the problem of particle-antiparticle asymmetry.

Erez Zohar