Energy loss in quantum tunnelling

Jean-Louis Basdevant

Jeffrey T. Morgan

Members of the University of Maine Physics Education Research Laboratory are studying student understanding of the phenomenon of quantum tunneling through a potential barrier, a standard topic in most introductory quantum physics courses. When a series of interviews revealed that many students believe energy is lost in the tunneling process, a survey was designed to investigate the prevalence of the energy‐loss idea. This survey was administered to populations of physics majors at the sophomore and senior levels. Data indicate that interview results are shared by a somewhat larger population of students and give insight into additional models of reasoning (e.g. analogies to macroscopic tunnels) not found in the interviews.

Shreyas Potnis, Ramón Ramos, Kenji Maeda +2 more

We experimentally study tunneling of Bose-condensed ^{87}Rb atoms prepared in a quasibound state and observe a nonexponential decay caused by interatomic interactions. A combination of a magnetic quadrupole trap and a thin 1.3 μm barrier created using a blue-detuned sheet of light is used to tailor traps with controllable depth and tunneling rate. The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes-classical spilling over the barrier, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate depends exponentially on the chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.

Antonio Defendi, Marco Roncadelli

A. I. Larkin, Yu. N. Ovchinnikov