Laser induced tunneling ionization in less than 12 attoseconds measured by attosecond angular streaking

In this paper we measured an "instantaneous" intensity independent tunneling delay time with an upper limit of 12 as [3]. Our experiments have given us direct access to the tunneling delay time with an unprecedented time accuracy of a few tens of attoseconds using attosecond angular streaking. Our results give strong indication that there is no real tunneling delay time and we expect that this will shed some light on the ongoing theoretical discussion on tunneling time and tunnel ionization in strong field physics.