Current-Carrying Quantum Dynamics (CCQD)

The independent Max Planck Research Group (MPRG) "Current-Carrying Quantum Dynamics" (CCQD) led by Dr. Ingo Barth was started in December 2014. The research of the CCQD group focuses on three research subareas:

Ionization dynamics in strong circularly polarized laser fields

This research is based on the theory of non-adiabatic tunnel ionization from electronic valence orbitals of noble gas atoms in strong circularly polarized laser fields. In our group, we develop further this theory and perform numerical TDSE calculations for halogen atoms or noble gas ions with five electrons in the valence shell, and for linear molecules with one electron in one of the doubly degenerate valence molecular π orbitals carrying electron currents. We also investigate the ionization dynamics in ring-shaped, for example benzene, or chiral and axisymmetric molecules possessing degenerate occupied molecular orbitals that also carry electron ring currents. In addition, there are spin-orbit splittings in ground states of halogen atoms and some molecules like NO, spin polarization of the photoelectrons can be controlled not only by strong circularly polarized laser fields but also by pre-selecting the ground state with respect to the magnetic quantum number, for example by using Stern-Gerlach experiment, multistage Zeeman decelerations of atoms and molecules, or even laser-controlled dissociation of the molecule. In strong circularly polarized laser fields, ionization preferences for one of the degenerate orbitals of chiral and axisymmetric molecules could potentially give us information about the chirality of the molecule.

Analysis and control of electron and nuclear currents

We calculate electron and nuclear ring currents as well as induced magnetic fields in different large molecules that can be controlled by circularly polarized laser pulses. We not only consider excited degenerate states but also ground electronic degenerate states of molecules carrying electron ring currents. Moreover, we also calculate spin-induced current densities based on the Dirac equation. In particular, the spin-degenerate ground spin-orbitals of the hydrogen atom have zero orbit-induced ring currents but non-zero spin-induced ring currents according to the non-zero magnetic quantum number of the electron spin. Laser control of such emission-free long-lived spin-induced ring currents in the ground state is challenging and it is being investigated in detail in our group. Finally, it is well known, that in the Born-Oppenheimer approximation the electron current densities in the electronic ground state in vibrating or even pseudo-rotating molecules and chemical reactions are exactly zero. To circumvent this Born-Oppenheimer flaw, new methods will be developed in our group to calculate non-zero electron current densities.

Development and documentation of STEM terms in German sign language

According to the 2008 UN convention on the rights of persons with disabilities, Deaf persons can access inclusive, high-quality and free education with equal opportunity compared to other persons. Theoretical chemist and quantum physicist Dr. Ingo Barth, 3rd generation Deaf, works in the development of the presently existing STEM (Science, Technology, Engineering and Mathematics) terms in German sign language. In cooperation with other Deaf scientists worldwide the STEM vocabularies in different sign languages will be researched, discussed, and extended.

The first STEM German workshop for Deaf scientists, doctors, and academics took place on June 12 and 13, 2015 at our institute. STEM terms in the form of videos are being documented and distributed on suitable online platforms such as Wikipedia. Furthermore, the STEM German workshop will regularly take place biannually.

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