Issue
EPL
Volume 82, Number 3, May 2008
Article Number 30009
Number of page(s) 6
Section General
DOI http://dx.doi.org/10.1209/0295-5075/82/30009
Published online 21 April 2008
EPL, 82 (2008) 30009
DOI: 10.1209/0295-5075/82/30009

Superluminal traversal time and interference between multiple finite wave packets

Xi Chen1 and Chun-Fang Li1, 2

1  Department of Physics, Shanghai University - 99 Shangda Road, Shanghai 200444, PRC
2  State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS Xi'an 710119, PRC

xchen@shu.edu.cn
cfli@shu.edu.cn

received 14 November 2007; accepted in final form 11 March 2008; published May 2008
published online 21 April 2008

Abstract
The mechanism of superluminal traversal time is investigated from the viewpoint of interference between multiple finite wave packets, due to the multiple reflections inside the well or barrier. In the case of potential well traveling that is classically allowed, each of the successively transmitted constituents is delayed by a subluminal time. When the thickness of the well is much smaller in comparison with a characteristic length of the incident wave packet, the reshaped wave packet with superluminal traversal time in transmission maintains the profile of the incident wave packet. In the case of potential barrier tunneling that is classically forbidden, though each of the successively transmitted constituents is delayed by a time that is independent of the barrier thickness, the interference between multiple transmitted constituents explains the barrier thickness dependence of the traversal time for thin barriers and its barrier thickness independence for thick barriers. This manifests the nature of the Hartman effect.

PACS
03.65.Xp - Quantum mechanics: Tunneling, traversal time, quantum Zeno dynamics.
42.25.Bs - Wave propagation, transmission and absorption.
73.40.Gk - Tunneling.

© EPLA 2008