Strong-field ionization of He by elliptically polarized light in attoclock configuration

We perform time-dependent calculations of strong-field ionization of He by elliptically polarized light in configuration of recent attoclock measurements of Boge et al. [Phys. Rev. Lett. 111, 103003 (2013)]. By solving a three-dimensional time-dependent Schr\"odinger equation, we obtain the angular offset θₘ of the maximum in the photoelectron momentum distribution in the polarization plane relative to the position predicted by the strong-field approximation. This offset is used in attoclock measurements to extract the tunneling time. Our calculations clearly support the set of experimental angular offset values obtained with the use of nonadiabatic calibration of the in situ field intensity, and disagree with an alternative set calibrated adiabatically. These findings are in contrast with the conclusions of Boge et al. who found a qualitative agreement of their semiclassical calculations with the adiabatic set of experimental data. This controversy may complicate interpretation of the recent attoclock measurements.