Seminar recording:
https://stanford.zoom.us/rec/share/mC6xNXcFF7JJiDdvqygkqwufWP1ajrRHtFy6RIuz-BeOxXw5k5gQxeC52LVOKrSC.Q3KOG9bEX0nWchPB
The fundamental quantum-mechanical concepts of quantum coherence and quantum entanglement are key to understanding the ultrafast, correlated many-electron dynamics triggered by attosecond X-ray pulses, such as the ones that can now be generated at LCLS-II using X-LEAP [1]. For example, quantum electronic coherence in photoionized molecules, arising at the attosecond and persisting at the femtosecond time scales, underpins the electron hole migration and therefore also the ensuing photochemical transformation of matter.
I propose a new fundamental, quantum-information-theory (QIT) based perspective on attosecond physics, with the main goal of constructing a complete theory for the full characterization, tomographic reconstruction and quantum control of entangled atto-ionized states, devising Bell tests to probe this entanglement and unveiling the effect of measurement on the quantum coherent many-electron dynamics.
The proposed theoretical effort relies on the new cutting-edge theoretical and computational approach that I recently developed to describe, from first principles, the quantum-coherent ionization dynamics triggered in atomic and molecular many-electron systems interacting with arbitrary laser fields, the time-dependent (TD) B-spline restricted correlation space (RCS) algebraic diagrammatic construction (ADC) method [2]. The TD B-spline ADC method [3] extends the ab initio ADC approach, originally developed to describe bound state dynamics [4], to the realm of ultrafast ionization dynamics, while the RCS technique [2] turns ab initio modeling of coherence and entanglement in photoionization of polyatomic molecular systems into a tractable problem.
I will describe how my new methodology allows us to accurately predict the mixed state of the ionized system prepared by attosecond and strong-field ionization of a molecular system [5]. I will also present recent applications of the TD B-spline RCS-ADC method to the simulation of complete numerical pump-probe experiments of ultrafast dynamics in molecular systems [6,7].
Achievement of the research objectives I have set, will initiate a new research program at the cross-roads between attosecond X-ray science and QIT, going hand in hand with the experimental progress at LCLS-II, conceptually transforming the realm of applications of attoscience and coincidence detection techniques [8], and expanding the scope of the emerging attosecond science program at SLAC towards quantum information theory and the fundamentals of quantum physics.
[1] J. Duris, et al, Nat. Phot., 14, 30 (2020).
[2] M. Ruberti, “Restricted Correlation Space B-Spline ADC Approach to Molecular Ionization: Theory and Applications to Total Photoionization Cross-Sections”, J. Chem. Theory Comput. 15, 6, 3635-3653 (2019).
[3] M. Ruberti, P. Decleva and V. Averbukh, “Multi-channel dynamics in high harmonic generation of aligned CO2: ab initio analysis with time-dependent B-spline algebraic diagrammatic construction”, Phys. Chem. Chem. Phys. 20, 8311-8325 (2018); V. Averbukh and M. Ruberti, “First-principles Many-electron Dynamics Using the B-spline Algebraic Diagrammatic Construction Approach” in “Attosecond Molecular Dynamics”, edited by Marc J. J. Vrakking and Frank Lepine, RSC Theoretical and Computational Chemistry series 13, 68-102 (2018).
[4] J. Schirmer, L. S. Cederbaum, and O. Walter, New approach to the one-particle Green's function for finite Fermi systems, Phys. Rev. A 28, 1237 (1983).
[5] M. Ruberti, “Onset of ionic coherence and charge dynamics in attosecond molecular ionization”, Phys. Chem. Chem. Phys. 21, 17584-17604 (2019).
[6] M. Ruberti, P. Decleva and V. Averbukh, “Full Ab Initio Many-Electron Simulation of Attosecond Molecular Pump–Probe Spectroscopy”, J. Chem. Theory Comput. 14, 10, 4991-5000 (2018).
[7] M. Ruberti, “Quantum electronic coherences by attosecond transient absorption spectroscopy: ab initio B-spline RCS-ADC study”, Faraday Discussions, (2020), DOI: 10.1039/D0FD00104J.
[8] J. Ullrich, R. Moshammer, A. Dorn, R. Dörner, L. Ph. H. Schmidt and H. Schmidt-Böcking, Recoil-ion and electron momentum spectroscopy: reaction-microscopes, Rep. Prog. Phys. 66, 1463 (2003).
