Insights into quantum tunneling via a phase-space approach

Quantum tunneling, as a quintessential quantum phenomenon, has been investigated in detail both theoretically and experimentally. Still, the physical picture of the tunneling process is not intuitive, leading to some confusion and paradoxes. In this paper, we have tried to gain insight into quantum tunneling by a phase-space approach. For this purpose, we scrutinize the evolution of the Wigner distribution during tunneling and derive the energy and momentum spectra by integrating over a segment of phase space. In this way, some of the difficulties and paradoxes in tunneling probability, energy conservation, and tunneling time are given a clearer interpretation. Negative probabilities in the Wigner distribution play a key role in the tunneling process, and the origin of negative probabilities clearly indicates that the volatility of matter underlies the various exotic phenomena involved.