Abstract
Quantum tunnelling is a phenomenon of non-equilibrium quantum dynamics and its detailed process is largely unexplored. We report the experimental observation of macroscopic quantum tunnelling 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 tunnelling. This non-equilibrium dynamics is analogue to tunnelling ionization. The imaged tunnelling process shows the splitting of matter wave packet by the potential barrier. The controversial “tunnelling 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.
Highlights
Quantum tunnelling is a phenomenon of non-equilibrium quantum dynamics and its detailed process is largely unexplored
The Bose–Einstein condensate (BEC) was produced in a hybrid trap with a crossed optical dipole trap (ODT) configuration, accompanied by a weak magnetic quadrupole field
The quantum tunnelling was demonstrated using a hybrid cross optical dipole trap and exerting a non-adiabatic kick, which results in a collective rotational motion in the condensate
Summary
Quantum tunnelling is a phenomenon of non-equilibrium quantum dynamics and its detailed process is largely unexplored. 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 out-coupled by quantum tunnelling. This nonequilibrium dynamics is analogue to tunnelling ionization. To study the time evolution of the tunnelling process, the condensate, degenerate as a single macroscopic wave function and directly observable in spatial and temporal scales, is an excellent platform to study such nonequilibrium dynamics[17,22]. As demonstrated in our report, tunnelling output atoms remained as condensates and were converted to quasi-one-dimensional matter wave pulses as a “passive” pulsed atom laser, which has no active output coupling mechanism and can be utilized for atom interferometer applications
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