title: Quantum effects in double ionization of argon below the threshold intensity.
abstract: So far, nonsequential double ionization (NSDI) of atoms can be well understood within a semiclassical or even classical picture. No quantum effect appears to be required to explain the data observed. We theoretically study electron correlation resulting from NSDI of argon in a low-intensity laser field using a quantum-mechanical S-matrix theory. We show that quantum interference between the contributions of different intermediate excited states of the singly charged argon ion produces a transition from back-to-back to side-by-side emission with increasing laser intensity, which is in close agreement with the experimental data. For higher intensities, this transition is enhanced by the consequences of depletion of the excited states.
authors.affiliation: HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100084, China, and Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088, China.
authors.forename: XiaoLei
authors.initials: X
authors.lastname: Hao
authors.affiliation: HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100084, China, and Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Institute of Theoretical Physics and Department of Physics, Shanxi University, 030006 Taiyuan, China.
authors.forename: WeiDong
authors.initials: W
authors.lastname: Li
authors.affiliation: Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Bingbing
authors.initials: B
authors.lastname: Wang
authors.affiliation: College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy, Max-Born-Strasse 2a, 12489 Berlin, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Becker