8 research outputs found
Pulse Propagation in Resonant Tunneling
We consider the analytically solvable model of a Gaussian pulse tunneling
through a transmission resonance with a Breit-Wigner characteristic. The
solution allows for the identification of two opposite pulse propagation
regimes: if the resonance is broad compared to the energetic width of the
incident Gaussian pulse a weakly deformed and slightly delayed transmitted
Gaussian pulse is found. In the opposite limit of a narrow resonance the dying
out of the transmitted pulse is dominated by the slow exponential decay
characteristic of a quasi-bound state with a long life time (decaying state).
We discuss the limitation of the achievable pulse transfer rate resulting from
the slow decay. Finally, it is demonstrated that for narrow resonances a small
second component is superimposed to the exponential decay which leads to
characteristic interference oscillations.Comment: 6 pages, 4 figure
Quantum theory of tunneling
In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks are critically examined. In addition by considering the analogy between evanescent waves in waveguides and in quantum tunneling, the times related to electromagnetic wave propagation have been used to explain certain aspects of quantum tunneling times. These topics are treated in both non-relativistic as well as relativistic regimes. Finally, a large number of examples of tunneling in atomic, molecular, condensed matter and nuclear physics are presented and solved.In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks ar