Research activities

In this project we investigate ground state and dynamical properties of Bose-Fermi mixtures and Fermi-spin-mixtures in optical lattices. Recently we have been looking at the intriguing dynamical properties of fermionic high-spin systems emplyoing the F=9/2 hyperfine manyfold of 40K. We observed fascinating phenomena ranging from collective spin oscillation of bulk systems to complex tensorial yet fully controllable spin-waves. In a deep optical lattice we performed benchmark experiments exploring spin changing dynamics on a two-body level. We are further interested in simulating highly relevant model systems to explore unknown and thus far unaccessible terrain towards a better understanding of phenomena like high-Tc superconductivity and elements of SU(N) magnetism as well as geomtrical frustration on a Fermionic triangular lattice and Graphene like systems in hexagonal periodic potentials.

In the Ytterbium Quantum Computing project we are building a Quantum computation and -simulation platform utilizing the alkaline-earth-like atom 171Yb. This isotope offers a multitude of viable advantages for encoding novel high-fidelity qubit and erasure conversion architectures. Its two-valence electron structure features a highly coherent metastable state, an optically active ion core for extended control and trapping configurations and single-photon Rydberg transitions for fast entangling gates. The ground and metastable state 1S0 and 3P0 both exhibit a decoupled nuclear spin of I=1/2 predestining 171Yb for an excellent Qu-bit.

The combination of different quantum objects into a new quantum hybrid system offers intruiging ways for realizing novel building blocks for quantum technology and allows the investigation and realization of completely new coherent interaction mechanisms as a resource for quantum communication and the creation of entanglement. In our experiment we couple ultracold atoms to cryogenically precooled nanomechanical resonators via lightfields. We cool the mechanical oscillator close to its motional ground state employing active feedback cooling and explore various coupling mechanisms involving external as well as internal degrees of freedom of the atoms. Our ultimate goal is the coherent coupling of two macroscopic quantum objects namely the ground-state-cooled oscillator and a Bose-Einstein condensate.

In the ERC-funded project "Engineering and probing anyonic quantum gases" (ANYON) we are working towards the realization of fractional quantum Hall states and their anyonic excitations in experiments with ultracold atoms. Such a realization in a well-controlled artificial quantum system with single-particle resolved imaging will allow for new insight into the intriguing strongly correlated states, which still pose open questions, and it might allow for the first direct observation of anyonic exchange statistics by manipulating the anyonic excitations

Ultrashort laser pulses enable us to observe and manipulate matter on very short time scales, whereas ultracold atoms permit experiments with high precision and controllability. This project aims at manipulating macroscopic quantum systems on ultrafast time-scales by, for example, instantaneously introducing long-range interactions by ionizing atoms in a quantum gas.

In earthbound experiments, studying the free evolution of a BEC is limited to less than 100 ms as the atoms fall out of the interrogation volume once released from their trap. This project overcomes this limitation by dropping a complete quantum gas setup down the 110 m high free fall tower at ZARM in Bremen allowing for a free expansion of 1 s. The system facilitates the investigation of the condensate's coherence in new regimes, the operation of highly sensitive atom interferometers and is an important stepping stone for future experiments on ballistic rockets or satellites.

Light & Schools begeistert junge Leute durch spannende Experimente für die Physik. Die Angebote richten sich sowohl an Mittel- als auch Oberstufenklassen der Hamburger Stadtteilschulen und Gymnasien. Das Schullabor wurde bereits 2009 im Rahmen der Landesexzellenzinitiative, die durch die Joachim Herz Stiftung gefördert wurde, ins Leben gerufen und wird derzeit im Rahmen des SFB 925 und des Exzellenzclusters „The Hamburg Centre for Ultrafast Imaging“ (CUI) fortgeführt.