Macroscopic Matter Wave Quantum Tunnelling

Quantum tunneling is a phenomenon of non-equilibrium quantum dynamics and its detailed process is largely unexplored. We report the experimental observation of macroscopic quantum tunneling of Bose-Einstein Condensate in a hybrid trap. By exerting a non-adiabatic kick to excite a collective rotation mode of the trapped condensate, a periodic pulse train, which remains as condensate, is then out-coupled by quantum tunneling. This non-equilibrium dynamics is analogue to tunneling ionization. The imaged tunneling process shows the splitting of matter-wave packet by the potential barrier. The controversial "tunneling time" question is found inadequate, from the point of view of wave propagation. The realized matter-wave pulse train can also be a passive pulsed atom laser for atom interferometer applications.