Physical Review Letters
Resolving Quantum Interference Black Box through Attosecond Photoionization Spectroscopy
Wenyu Jiang, Gregory Armstrong, Lulu Han, Yidan Xu, Zitan Zuo, Jihong Tong, Peifen Lu, Jan Marcus Dahlström, Kiyoshi Ueda, A. C. Brown, H. W. van der Hart, Xiaochun Gong, Jian Wu
Abstract
Multiphoton light-matter interactions invoke a so-called "black box" in which the experimental observations contain the quantum interference between multiple pathways. Here, we employ polarization-controlled attosecond photoelectron metrology with a partial wave manipulator to deduce the pathway interference within this quantum 'black box" for the two-photon ionization of neon atoms. The angle-dependent and attosecond time-resolved photoelectron spectra are measured across a broad energy range. Two-photon phase shifts for each partial wave are reconstructed through the comprehensive analysis of these photoelectron spectra. We resolve the quantum interference between the degenerate p→d→p and p→s→p two-photon ionization pathways, in agreement with our theoretical simulations. Our approach thus provides an attosecond time-resolved microscope to look inside the "black box" of pathway interference in ultrafast dynamics of atoms, molecules, and condensed matter.