Quantum coherence in molecular photoionization

Abstract

The study of onset and decay, as well as control of ultrafast quantum coherence in many-electron systems is in the focus of interest of attosecond physics. Interpretation of attosecond experiments...

Influence of nuclear dynamics on molecular attosecond photoelectron interferometry

“…The autocorrelation function expresses the overlap between the time-dependent nuclear wave packet χ( q , τ) after the time delay τ and the initial wave packet χ( q , 0) created in the cation ( q indicates the nuclear coordinate). A closely related approach was already adopted to describe nuclear-motion effects in HHG ( 12 , 16 , 39 , 40 ) and attosecond electron-hole migration ( 8 , 41 , 42 ). The modulation depth B ( p ) of the sideband as a function of the final electron momentum p is proportional to the product of the electronic matrix element M ( p ) and the Fourier transform of the nuclear autocorrelation N (ɛ p )Bfalse(pfalse)∝Mfalse(pfalse)Nfalse(normalεpfalse)where ɛ p is the vibrational energy and M ( p ) is averaged over the ground state (zero-point energy) vibrational function (see equations 7 and 8 in the Supplementary Materials).…”

Generation of entanglement using a short-wavelength seeded free-electron laser

“…The degree of entanglement of the dressed ion and the photoelectron can be theoretically examined, for the case of a single atom (pure state) interacting with a laser field, using the von Neumann entropy of entanglement, S = −Tr[ρ P log 2 (ρ P )]. This depends on the reduced density matrix of the photoelectron, ρ P , conditioned on the photoionization event (34,35). Despite being a difficult quantity to estimate (44,45), the von Neumann entropy is a quantitative measure of the lack of knowledge of the ionic (electronic) system due to its entanglement with an unresolved photoelectron (ion): S = S P = S I .…”

“…The final state (F) is then entangled because the wavefunctions of the ion (I) and the photoelectron (P) cannot be factorized (34), i.e., |Ψ (F) 〉 ≠ |ψ (I) 〉 ⊗ |ψ (P) 〉.…”

Advances in modeling attosecond electron dynamics in molecular photoionization

“…Theoretical prediction of the quantum coherences of Equation ( 2) 18 is essential for our fundamental understanding of the physics underlying photochemical transformations at ultrashort timescales, as it allows us to reconstruct the ultrafast coherent electron dynamics that can be triggered by the photoionization process in the parent molecular ion. Key theoretical targets also include the unveiling of the specific mechanisms that govern the onset of ionic coherence in ultrafast outer-and inner-shell ionization of molecular systems, as well as a deeper understanding of the level of entanglement produced in the photoionization process and the consequent role of measurement on the observation of the ensuing dynamics.…”