Decay of symmetry-protected quantum states

Bychek, Anna A.; Maksimov, Dmitrii N.; Kolovsky, Andrey R. Physical Review A. DOI:https://doi.org/10.1103/PhysRevA.102.033324

We study the decay of bosonic many-body states in the triple-well Bose-Hubbard model where bosons in the central well can escape into a reservoir. For vanishing interparticle interaction this system supports a nondecaying many-body state which is the antisymmetric Bose-Einstein condensate with particles occupying only the edge wells. In the classical approach this quantum state corresponds to a symmetry-protected nondecaying state which is stable even at finite interaction below a certain intensity threshold. Here we demonstrate that despite the fact that the classical counterpart is stable the antisymmetric Bose-Einstein condensate is always metastable at finite interatomic interactions due to quantum fluctuations.