Attoclock revisited on electron tunnelling time Cornelia Hofmann1,2, Alexandra S. Landsman1,3, Ursula Keller2 Attoclock Method [1-3] 1Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany 2Department of Physics, Institute of Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland 3Max Planck Postech/Department of Physics, Pohang, Gyeongbuk 37673, Republic of Korea [1] Hofmann, et al., http://arxiv.org/abs/1901.07015 [2] Eckle, et al., Science, 322, 1525-1529 (2008) [3] Landsman, et al., Optica 1, 343 (2014) [4] Dörner, et al., Phys. Rep. 330, 95 (2000) [5] Weger, et al., Opt. Express 21, 21981–21990 (2013) [6] Camus, et al., Phys. Rev. Lett. 119, 023201 (2017) [7] Wigner, Phys. Rev. 98, 145–147 (1955) [8] Fortun, et al., Phys. Rev. Lett. 117, 010401 (2016) [9] Sainadh, et al., http://arxiv.org/abs/1707.05445 [10] Bray, et al., Phys. Rev. Lett. 121, 123201 (2018) [11] Ivanov, Kheifets, Phys. Rev. A 89, 21402 (2014) [12] Hofmann, et al., New J. Phys. 18, 043011 (2016) [13] Teeny, et al., Phys. Rev. Lett. 116, 063003 (2016) [14] Ni, et al., Phys. Rev. A, 98, 013411 (2018) [15] Ivanov, et al., Comm. Phys. 1, 81 (2018) [16] Emmanouilidou, et al., J. Phys B: At. Mol. Opt. Phys. 48, 245602 (2015) [17] Majety, Scrinzi, J. Mod. Opt. 0340, 1–5 (2017) [18] Reiss, J. Phys B: At. Mol. Opt. Phys. 47, 204006 (2014). [19] Büttiker, Phys. Rev. B 27, 6178–6188 (1983) References Principle: final photoelectron momentum encodes moment when electron first entered the laser field dominated continuum Measurements: ● helium ionized by strong-field near IR ● ● Keldysh Parameter between 0.75 and 4 ● COLTRIMS [4] & VMIS [5] experimental setup ● random Carrier-Envelope-Offset phase ● observable: streaking offset angle of the photoelectron momentum distribution Other Experiments Krypton/argon Attoclock [6] ● Comparing streaking angle between two species ● gas mixture in COLTRIMS [4] ● Wigner trajectory [7] calculations with delay matches Non-Adiabatic Effects Dipole Approximation Summarized Influence on Attoclock Interpretation [1] Larmor time [19] and Feynman Path Integral method [3] yield estimates comparable to measured Attoclock tunnelling delays Acknowledgements Assumptions Single Active Electron (SAE) Time Reconstruction: ● Single Classical Trajectory (SCT) simulation assuming instantaneous tunnelling ● offset angle = ellipticity correction + delay BEC of rubidium atoms in optical lattice [8] ● kicked lattice → oscillating wave packet ● lattice turned off → instantaneous momenta mapped to location on detector ● D2 (tunnelled) is delayed compared to D1 (reflected) Atomic hydrogen Attoclock [9] ● Measurement compared to TDSE agree ● approximation for Coulomb scattering [10] ● TDSE with Yukawa potential: ● tunnelling delay ● ionisation time extracted from experiment Attoclock assumption ● tunnelling most probable when field is at maximum ● = peak of the pulse envelope = 0 approaches solving the TDSE ● probability current density [13] maximised at < 0 ● classical packpropagation after TDSE forward calculation [14] finds classical turning point ● instantaneous ionization rate depending on fluctuations of the strong field [15] contradicts = 0 → starting time before the peak of the envelope would result in even larger extracted tunnelling delays Post-ionization [16] ● classical trajectories ● 2 electrons (bound- free) yields same result as SAE assuming perfect screening Full process [17] ● TDSE calculation where one electron is allowed to ionise ● compared to SAE TDSE ● no electron correlation visible in the angular photoelectron momentum distribution ● agreement with non-adiab. calibrated measurement for time-dependent Schrödinger equation (TDSE) [11] ● initial transverse momentum → lower field strength calibration for same data [12] ● energy gain → shorter exit radius → still remaining offset angle difference ● near IR ≈ 800 nm wavelength ● Intensity below 8∙1014 W/cm2 → spatial dependence of the electric field neglected → magn