Quantum dynamics of atomic and molecular systems

Our group studies atomic and molecular quantum systems with respect to their interactions on different levels of complexity. Of special importance is the application and extension of modern methods for the manipulation and quantum control to many-body quantum systems, in particular using coherent light. The systems under investigation range from highly excited Rydberg atoms over atomic and molecular quantum gases to molecular aggregates. The group develops technologies for trapping and cooling of neutral atoms as well as quantum-state sensitive diagnostics.

Latest news from the lab

The PhD work of Juris Ulmanis published in the book series Springer Thesis 10.03.2017

Juris Ulmanis from the mixtures team receives the Springer thesis award for his PhD work. Congratulations!

His thesis explores the Efimov scenario, which is one of the prime examples of how fundamental quantum physics universally transpire across seemingly disparate fields of modern science. Initially speculated for nuclear physics more than 40 years ago, the Efimov effect has become a new research paradigm not only in ultracold atom physics but also in molecular, biological and condensed matter systems. In his work, Juris used a heteronuclear mixture of ultracold Li and Cs atoms to measure the scaling factor, which is a hallmark property and sometimes referred to as the “holy grail” of Efimov physics. These results allowed to pioneer experimental understanding of universal properties that unify the description of different three-body systems, as well as to discern microscopic, non-universal properties that sets different systems apart.

The book features a completely rewritten introduction that is aimed at young scientists just starting in the field of few-body physics. On top of a light primer on the Efimov effect, it highlights aspects of three-body physics in ultracold quantum gases and places these ideas in a wider context touching nuclear, atomic, and molecular physics. The rest of the work closely follows the original thesis.

For more information:
Read the book on Springer Theses

Binh Tran receives Poster Prize at Summer School in São Paulo10.02.2017
Binh Tran

During the "School on Interaction of Light with Cold Atoms" in São Paulo for young students and researchers, Binh Tran from the Mixtures team presented a poster with the title “Towards creating Bose and Fermi Polarons in an ultracold Li-Cs Mixture with a large Mass Ratio” which was selected as the best poster. Congratulations!

For more information:
Website: School on Interaction of Light with Cold Atoms

Review of the EU Training Network on Rydberg physics published as a special issue of the EPJ04.01.2017

The recently published special issue of the European Physical Journal (EPJ) reviews achievements of the EU Integrated Training Network on Rydberg Physics. The training network, which is going under the abbreviation COHERENCE and was funded from 2012 to 2015 by the European Commission, was devoted to promote young researchers in the field of Rydberg gases. The central research topic was the investigation of interactions among highly excited (Rydberg) atoms under extremely controlled conditions. This kind of research has many applications in fundamental science and technology at the crossroads between atomic, molecular and condensed matter physics, quantum optics, quantum simulation, and others. Our research group, representing Heidelberg University, was one of the leading teams among 18 European and US universities and research institutions that were involved in the network. During the project more than 100 articles in high-impact journals were published. This special issue summarizes the major scientific results of COHERENCE in a series of 15 review-style articles.

For more information:
Read the complete special issue here (open access!): Cooperativity and Control in Highly Excited Rydberg Ensembles - Achievements of the European Marie Curie ITN COHERENCE
Contribution from our group: Gavryusev et al., Interaction Enhanced Imaging of Rydberg P states, Eur. Phys. J. Spec. Top. 225, 2863 (2016)

For more highlights see our news page

Research topics

Mixtures of ultracold atoms and molecules

In this experiment we use a mixture of two different alkali metals: cesium and lithium. This gives us the possbility to form ultracold LiCs dimers. These molecules have an extremely large electric dipole moment which promises many new experiments. For example, the molecules can be orientated in an external electric field.

Strongly-correlated Rydberg quantum gases

Rydberg atoms are atoms in highly excited electronic states. These atoms are very sensitive to external fields and experience extremely strong interactions with other Rydberg atoms. This gives us a model system for studying strongly-correlated quantum systems that is highly controllable and completely governed by interatomic interactions.

Collisions of highly charged ions and cold atoms

We are currently setting up this new experiment. Our goal is to investigate multiple electron capture using the combined techniques of magneto-optically cooling and trapping of the target atoms and using recoil ion momentum spectroscopy.

Hybrid ion atom trap for cold chemistry experiments

Interactions between ions and neutrals play an important role in all kind of chemical reactions. In order to gain a full understanding of these systems we are trying to observe reactions at ultra-low temperatures. In this regime the reaction dynamics are no longer concealed by the thermal movement of the particles.

Rydberg physics with ultracold two-electron systems

We are setting up an experiment to study the physics of two-electron Rydberg atoms using a quantum gas of ultracold strontium. The experiment is located at the University of Science and Technology of China (USTC Shanghai Institute for Advanced Studies). First studies will be aiming to explore many-body effects induced by the long-range interactions between highly excited strontium Rydberg atoms, using the inner electron to control the atom's motion and to detect single Rydberg atoms.