Quantum Optics Group (LMU) - Quantum Many Body Systems Division (MPQ)

By using a combination of Ramsey interferometry and Bloch oscillations we implement a protocol to extract the geometric phase of a one-dimensional dimerized optical lattice modelling polyacetylene. This one-dimensional Berry phase, also known as Zak phase, can be viewed as an invariant characterizing the topological properties of the energy bands.

Nature Physics 9, 795-800 (2013)

Press Release MPQ (english, deutsch)

We implemented large uniform effective magnetic fields with ultracold atoms using laser-assisted tunneling in a tilted optical lattice. We also show that for two atomic spin states with opposite magnetic moments, our system naturally realizes the time-reversal-symmetric Hamiltonian underlying the quantum spin Hall effect. Phys. Rev. Lett. 111, 185301 (2013)

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Press Release MPQ (english, deutsch)

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Using our quantum gas microscope we succeeded to observe magnon bound states in one-dimensional quantum magnets. These two-body bound states have been predicted to exist in Heisenberg chains by Hans Bethe 80 years ago. Using a novel microscopic preparation and detection method we identify the states by their characteristic correlations and, furthermore, we observe their dynamics. Nature 502, 76–79 (2013), Press Release MPQ (english, deutsch).

See also: News and views by Sougato Bose

Manuel Endres receives the PhD prize of the "Münchner Universitätsgesellschaft" for his thesis "Probing correlated quantum many-body systems at the single-particle level"

Press Release MPQ


We observed coherent motion of a single spin down atom embedded in an environment of spin up atoms. Our measurements revealed coherent superexchange dynamics over large distances in the Mott insulating regime. In the superfluid regime we observed polaronic physics which lead to a reduced spreading speed due to the strong impurity-bath interactions. Nature Physics 9, 235-241 (2013), Press Release MPQ (english, deutsch).

See also: News and views by Patrick Windpassinger

We could for the first time observe a negative absolute temperature for mobile particles. By using an intermediate bosonic Mott insulator together with a Feshbach resonance in bosonic Potassium we were able to create a stable attractive Bose gas at negative absolute temperature.
Science 339, 52 (2013).

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Prof. Nigel Cooper, winner of a Humboldt Research Award, has joined our group in January 2013 as a guest scientist for three months. Nigel Cooper is an internationally renowned Professor of Theoretical Physics at the University of Cambridge where he leads a group working on Theory of Condensed Matter, and he is Fellow of Pembroke College. During his stay in Munich he will work in the field of artificial gauge fields and topological phases with our group at MPQ and LMU, as well as the group of Prof. Wilhelm Zwerger at TUM.