Dr Alessandro Zenesini

False vacuum decay in a ferromagnetic superfluid

In quantum field theory, the decay of an extended metastable state into the real ground state is known as ``false vacuum decay'' and it takes place via the nucleation of spatially localized bubbles. Despite the large theoretical effort to estimate the nucleation rate and intriguing speculations over the fate of our universe, experimental observations were still missing. In our experiment, we observe bubble nucleation in isolated and highly controllable superfluid atomic systems, and we find good agreement between our results, numerical simulations and instanton theory opening the way to the emulation of out-of-equilibrium field phenomena in atomic systems.