Quantum tunneling time is a highly debated topic – we explain why

We discuss the attoclock technique to extract tunneling delays from He atoms with regards to the typical approximations such as the dipole approximation, non-adiabatic effects, photoelectron momenta at the tunnel exit, electron correlation and exit coordinate.

We can confirm that the He attoclock measurement is in agreement with finite tunneling time models. 

However, the adiabatic approximation gives the wrong field strength calibration which effectively increases the tunnel barrier width (Fig. 13). Unresolved is the issue of the starting time of the tunneling process. Some results indicate a starting time before the peak of the electric field which would increase the tunneling time shown in Fig. 12 and 13. Single active electron time-dependent Schrödinger equation (TDSE) calculations overlap with the non-adiabatic data (Fig. 6) - mostly within the error bars.

Reference:
Hofmann, C., Landsman, A.S., and Keller, U. (2019). Attoclock revisited on electron tunnelling time. J Modern Opt 66, 1052-1070. (external pagehttps://doi.org/10.1080/09500340.2019.1596325call_made)

NCCR MUST highlight:
external pagehttp://www.nccr-must.ch/highlights/keller_2542019.htmlcall_made