With the advent of new and tunable light sources, the electron dynamics of atoms and ions can nowadays be studied in great detail, from the femtosecond down to the attosecond scale. For instance, the irradiation of matter with intense FEL pulses hereby results in a large number of induced ionization, auto-ionization and recombination processes. To explore these - explicitly time-dependent - processes, we apply the density matrix theory to the emission and capture of electrons, and which combines analytical model with often extensive computations in order to achieve a quantitative (and predictive) understanding of light-matter interactions in strong fields. Beside of such atomic processes, we also investigate twisted particle beams carrying quantized angular momentum and the properties of highly-charged ions for their application in astro, nuclear and plasma physics.

## Research area

Prof. Fritzsche's research interests deal with the structure and dynamics of finite quantum systems for applications in atomic, optical and nuclear physics. Current research topics are:

- time-dependent multi-photon ionization dynamics in intense FEL radiation
- auto-ionization and Auger cascades of atomic and molecular systems
- light-matter interactions and light scattering in strong Coulomb fields
- the structure and spectroscopy of heavy and radio-active isotopes
- particle beams carrying quantized orbital angular momentum
- parity and time-reversal violating interactions in atoms and ions

## Teaching field

Prof. Fritzsche ́s teaching has as its focus the behavior of correlated quantum systems and includes courses in:

- atomic structure and collision theory
- light-matter interactions in strong and short pulses
- computational quantum physics

## Research methods

Various concepts and theoretical techniques are applied by Prof. Fritzsche's group for studying the structure and light-matter coupling of finite quantum systems, including:

- relativistic atomic & many-body theory
- numerical simulation techniques and code development
- time-independent and time-dependent density matrix theory
- computer-algebraic techniques
- concepts and protocols from quantum information theory and quantum state estimation

>> link to the Relativistic Quantum Dynamics Group