Attosecond Spatial Control of Electron Wavepacket Emission Dynamics and Electron-Electron Correlation in Double Ionization

Using orthogonally polarized two-color (OTC) laser fields on neon and coincidence momentum imaging we gain access to the Coulomb influence in single ionization on sub-cycle times, and demonstrate control over the two electron-emission dynamics in double ionization. We show that tuning the relative phase of the OTC fields allows dictating whether the two electrons are predominantly emitted in a correlated or anti-correlated manner. Angström and attosecond control of free electron wave packets is one of the pinnacles of attosecond science. Orthogonally polarized two-color (OTC) laser fields allow to control the motion of fieldionizing electronic wave packets both in time and space [1]. In OTC pulses time and space are connected and thus an attosecond time scale is established in the polarization plane for both the emitted and the recolliding wave packets [2]. Figure 1. Comparison of experimental (a) and calculated (b)-(d) electron-momentum distributions. (b) Solutions of the TDSE. (c),(d) CTMC simulations without (c) and with (d) inclusion of the ionic potential. Intensity I800nm = I400nm = 1×10 14 W/cm 2 in all panels. We report on experiments that use OTC pulses for studying single and double ionization of neon using the COLTRIMS technique. In our experiments OTC pulses were produced by combining an 800 nm laser pulse, frequency ω, and its second harmonic pulse, frequency 2ω, in a collinear geometry at a rate of 5 kHz with an adjustable relative phase, Δφ, between the two colors. Measured electron spectra correlated with singly ionized neon [Fig. 1] show that the electron emission direction is highly sensitive to the shape of the OTC field, featuring asymmetric emission patterns that vary with Δφ. By exploiting the time to momentum space mapping provided by OTC fields (in combination with simulations) we found [3] that depending on their sub-cycle birth time the trajectories of photoelectrons are affected differently by the ion’s Coulomb field. While recollision trajectories are focused, direct trajectories are defocused or strongly scattered. This results in a timing failure of the mapping provided by the OTC filed on the order of 2π/(32ω). Figure 2. (a) Ne 2+ pz momentum (other directions integrated over) as a function of relative phase Δφ (upper panel). Ne 2+ px momentum (lower panel). (b) Δφ dependent mean value of pz (red dots) and px (blue squares). lower panel: width of pz (red dots) and px (blue squares). Intensity I800nm = I400nm = (2±0.2)×10 14