On Universal Properties of Tunnelling

Günter Nimtz

Guenter Nimtz

How much time does a tunneling wave packet spent in traversing a barrier? Quantum mechanical calculations result in zero time inside a barrier . In the nineties analogous tunneling experiments with microwaves were carried out. The results agreed with quantum mechanical calculations. Electron tunneling time is hard to measure being extremely short and parasitic effects due to the electric charge of electrons may be dominant. However, quite recently the atomic ionization tunneling time has been measured. Experimental data of photonic, phononic, and electronic tunneling time is available now and will be presented. It appears that the tunneling time is a universal property independent of the field in question.

P. Fr�brich, R. Lipperheide, K. M�hring

M. Kraev

Eugene Wongb, Ian K. Affleck

Tunneling through a localized barrier in a one-dimensional interacting electron gas has been studied recently using Luttinger liquid techniques. Stable phases with zero or unit transmission occur, as well as critical points with universal fractional transmission whose properties have only been calculated approximately, using a type of "ϵ-expansion". It may be possible to calculate the universal properties of these critical points exactly using the recent boundary conformal field theory technique, although difficulties arise from the infinite number of conformal towers in this c = 4 theory and the absence of any apparent "fusion" principle. Here, we formulate the problem efficiently in this new language, and recover the critical properties of the stable phases.

J. M. Combes, Pierre Duclos, Ruedi Seiler