Groups associated to the ZOQ
Ultrafast optical physics
Using extremely short pulses of light at wavelengts reaching from short-wave x-rays into the long-wave terahertz regime, the light-matter interaction is explored at the 'natural' time-scales of electrons and atoms. A particular focus is the transfer of coherence between light and quantum objects like atoms and molecules, but also Bose-Einstein-Condensates.
The group studies the interaction between light and matter at ultralow temperatures. The focus is on quantum gases in optical lattices and high finesse optical cavities.
Nachwuchsgruppe Kränkel – Solid-state laser development
The research activities of the group are focused on solid-state lasers including the crystal growth, development, and fundamental characterization of new laser materials. In particular, the efficiency and dynamics of diode pumped bulk and waveguide lasers are studied in the visible, near and mid infrared spectral region.
The group studies fermionic quantum gases at nano-Kelvin temperatures experimentally. Making use of the unprecedented progress in controlling and probing many-body systems we investigate e.g. fermionic superfluidity in reduced dimensions and mesoscopic quantum gases.
Nonlinear Quantum Optics
Optical quantum technologies are at the heart of the group’s research. The group has been researching the generation and application of squeezed and entangled laser light in the fields of gravitational-wave detection, macroscopic quantum physics, and optical communication. In 2015, the group realized the first one-sided device independent quantum key distribution using Gaussian entanglement.
Quantum Gases and Spectroscopy
The main foci of the research group are ultra-cold quantum gases in optical lattices, high precision spectroscopy and fiber laser development.
The main focus of our ZOQ-related research activities is the realization of a strongly coupled hybrid quantum system (HQS) between a nanomechanical resonator and ultracold atoms, thereby achieving the entanglement and coherent state transfer within the HQS. A sophisticated 'membrane-in-the-middle' fiber cavity set-up inside a 30 mK dilution refrigerator together with quantum optical cooling schemes are used to prepare the macroscopic mechanical resonator in the quantum-mechanical ground state. The experiments are done in close cooperation with the quantum optics group of Prof. Sengstock while our theory activities are based on a collaboration with the group of Prof. Thorwart.
Many-body theory of ultra-cold atom systems
We investigate the theory of ultracold atom and solid state systems, with particular emphasis on many-body effects. One of our primary research interest is many-body dynamics, such as dynamic phase transitions and dynamic control of many-body systems, as well as properties of superfluidity and superconductivity. Furthermore, we study the equilibrium phase diagrams of ultra-cold atoms, at both finite and zero temperature. Another objective is the advancement of the technology of ultra-cold atom systems , for example by investigating new cooling and detection methods.
Quantum Theory of Condensed Matter
Fundamental Processes in Quantum Physics
Research foci of the group are the nonequilibrium dynamics of ultracold bosonic and fermionic quantum gases, highly excited Rydberg atoms and molecules in external fields, nonlinear excitations such as solitons and vortices of Bose-Einstein condensates, ultracold scattering and directed transport in spatiotemporally driven lattices. Very recently a theory of local symmetries has been developed that is now pursued in various directions concerning wave mechanical systems.