Stepwise Quantum Tunneling Seen in Ultracold Atoms

Jianhua, Wu, Qi +4 more

W. K. Hensinger, Hartmut Häffner, Antoine Browaeys +7 more

W. K. Hensinger, Hartmut Häffner, Antoine Browaeys +8 more

Fazal Badshah, Abdul Basit, Hamad Ali +3 more

Eric Varoquaux

Striking observations of quantised events in superfluid flow through a microscopic orifice have been made recently at Orsay, France. Sudden, stepwise reductions of the flow velocity at the critical velocity threshold, seen both in superfluid 3 He and 4 He, are interpreted as slips by 2π of the phase of the quantum mechanical wavefunction that describes the condensate of the superfluid. Moreover, in superfluid 3 He slightly below the superfluid transition, at low pressure and at a temperature of 0.9 mK, the mass flow through the orifice becomes fully dominated by quantum mechanics.

Manju Perumbil, Kyle S. Hardman, M. A. Sooriyabandara +5 more

The transmission of an interacting Bose-Einstein condensate incident on a repulsive Gaussian barrier is investigated through numerical simulation. The dynamics associated with interatomic interactions are studied across a broad parameter range not previously explored. Effective one-dimensional Gross-Pitaevskii equation (GPE) simulations are compared to classical Boltzmann-Vlasov equation (BVE) simulations in order to isolate purely coherent matter-wave effects. Quantum tunneling is then defined as the portion of the GPE transmission not described by the classical BVE. An exponential dependence of transmission on barrier height is observed in the classical simulation, suggesting that observing such an exponential dependence is not a sufficient condition for quantum tunneling. Furthermore, the transmission is found to be predominately described by classical effects, although interatomic interactions are shown to modify the magnitude of the quantum tunneling. Interactions are also seen to affect the amount of classical transmission, producing transmission in regions where the noninteracting equivalent has none. This theoretical investigation clarifies the contribution quantum tunneling makes to overall transmission in many-particle interacting systems, potentially informing future tunneling experiments with ultracold atoms.