1205.2004 (Michael Klaiber et al.)

Under-the-barrier dynamics in laser-induced relativistic tunneling    [PDF]

Michael Klaiber, Enderalp Yakaboylu, Heiko Bauke, Karen Z. Hatsagortsyan, Christoph H. Keitel

The tunneling dynamics in relativistic strong-field ionization is investigated with the aim to develop an intuitive picture for the relativistic tunneling regime. We demonstrate that the tunneling picture applies also in the relativistic regime by introducing position dependent energy levels. The relativistic quantum dynamics in the classically forbidden region features two characteristic time scales: the time for the formation of momentum components of the ionized electron wave packet (Keldysh time) and the time interval which the electron wave packet spends inside the barrier (Eisenbud-Wigner-Smith time delay). While the Keldysh time determines an electron momentum shift under the barrier along the laser propagation direction, the Eisenbud-Wigner-Smith time delay governs the corresponding wave-packet's spatial drift. The signature of the momentum shift is shown to be present in the ionization spectrum at the detector and, therefore, observable experimentally. In contrast, the signature of the Eisenbud-Wigner-Smith time delay disappears at far distances for pure tunneling dynamics.

View original: http://arxiv.org/abs/1205.2004