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

QUANTUM

Welcome! We are carrying out research in the field of quantum optics and quantum many-body systems using ultracold atomic and molecular quantum gases at the Max-Planck Institute for Quantum Optics and the Ludwig-Maximilians University.

If you are interested in joining our team click here! 

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)

Viewpoint Physics

Physicsworld

Press Release MPQ (english, deutsch)

Media Gallery

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).

See also:
New: Frequently asked questions
Nature News article
Science perspective by Lincoln Carr
Press Release
Pressemitteilung
Media Gallery

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. 

We observed spatially ordered structures of collective excitations in a gas of laser excited Rydberg atoms. The comparison of the measured excitation dynamics to a theoretical model developed by our colleagues at the MPIPKS in Dresden provides evidence for coherence between the different excitation patterns. Nature 491, 87-91 (2012), Press Release MPQ (english, deutsch)

We congratulate Simon Braun and the whole team on the Poster Prize of the AMO division of the French Physical Society (PAMO) award at the ICAP 2012 for the poster on "Negative absolute temperature for motional degrees of freedom" (ArXiv:1211.0545

 

We detected a Higgs-type excitations in a low-dimensional system of ultracold atoms at the transition between different phases of matter. The work was done in close collaboration with colleagues from Harvard and Caltech. Nature 487, 454-458 (2012), Press Release MPQ (english, deusch), Additional Media

In a collaboration with theoretical physicists from Potsdam, Brisbane, Jülich and the LMU, we have investigated the relaxation of a bosonic density wave towards equilibrium. Using an optical superlattice, we were able to prepare the initial state with high fidelity and to follow the dynamics in terms of quasi-local densities, currents and coherences. Nature Physics 8, 325 (2012). Cover Story. (Additional Media)

By means of two perpendicular superlattices we have realized a three-dimensional array of independent plaquettes where we studied the spin physics of four site localized bosonic particles. We were able to observe valence bond oscillations as well as to create and characterize two resonating valence bond states with s- and d-wave symmetry.These two states constitute a minimum basis of a topologically protected qubit. Phys. Rev. Lett. 108, 205301 (2012).

We studied the expansion of an initially confined fermionic quantum gas in the lowest band of a homogeneous optical lattice and observed a crossover from ballistic transport for non-interacting atoms to an almost bimodal dynamics in the interacting case. Nature physics 8, 213  (Additional Material)

We observed how correlations propagate across a one-dimensional bosonic Mott insulator after the system has been set out of equilibrium. Our measurements show that the dynamics is bounded by a maximum velocity, reminding of the light cone that separates time-like from space-like intervals in the theory of special relativity. Nature 481, 484 (2012). Press release MPQ (deueng). Additional Media.

Prof. Christophe Salomon, laureate of Gay-Lussac-Humboldt prize 2011, has joined our group on January 2012 as a guest scientist. 
Christophe Salomon is research director at C.N.R.S.- Laboratoire Kastler Brossel at the  Ecole Normale Supérieure in Paris. There he leads a group on Ultra cold fermi gases, which has been responsible for seminal advancements in the field.  During his stay in Munich he will work in the field of ultracold quantum gases at MPQ and LMU. 

We have realized a strong effective magnetic field in an optical lattice, which should allow one to investigate fractional quantum Hall physics and beyond with ultracold atoms. The Aharonov-Bohm phase is simulated using Raman-assisted atom tunneling. We observe that the effective magnetic field leads to a frustrated ground state and to quantum cyclotron orbits. Phys. Rev. Lett. 107, 255301 (2011). Viewpoint Physics.

We succeeded in directly imaging quantum fluctuations that show up as particle-hole pairs in a bosonic Mott insulator. The pairwise appearance of the fluctuations also leads to a non-local order that we probed in the experiment. Science 334, 200 (2011). Press release MPQ (deu, eng). MPG (deu). Additional Media

Coherent light scattering from only a few hundred atoms in atomic Mott insulator yields a far-field diffraction pattern. We used this technique to detect one-dimensional antiferromagnetic order via additional diffraction peaks. Phys. Rev. Lett. 106, 215301 (2011). Viewpoint Physics.

 

 

With lattice shaking, we are able to control correlated tunneling and superexchange interactions in isolated double well potentials. This technique opens the possibility to simulate an arbitrary XXZ spin model. Phys. Rev. Lett. 107, 210405 (2011)

We addressed and changed the spin of individual atoms in an optical lattice with laser light and arranged the atoms in arbitrary patterns. These results are an important step towards large scale quantum computing and for quantum simulation of condensed matter systems [Nature 471, 319 (2011)]. Press release MPQ (deu, eng), MPG (deu). Nature Physics News & Views, Additional media.

We have experimentally realized few-body impurity systems consisting of a single fermion and a miniature Bose-Einstein condensate. Using quantum phase revival spectroscopy, we revealed how the presence of the interacting impurity fermion modifies the interactions among the bosons. Phys. Rev. Lett 106, 115305 (2011)

We have studied the non-equilibrium dynamics in tunnel coupled 1D Bose liquids, extending the famous Landau-Zener problem to a low-dimensional many-body setting. Most strikingly, we found a drastic breakdown of the adiabatic transfer between the Bose liquids upon Landau-Zener sweeps in the highest-energy states [Nature Physics 7, 61 (2011)]. Press release MPQ (deu, eng).

EVENTS

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SEMINARS

Group Seminar LMU: Adiabatic growing of Laughlin states of lattice bosons in artificial gauge fields

Tuesday, 15.04.2014 10:00 a.m. (s.t.) in H107, Fakultät für Physik, LMU

Fabian Grusdt, TU...

Group Seminar LMU: A time-dependent tour with novel phenomena in attractive and repulsive Bose-systems

Tuesday, 08.04.2014 10:00 a.m. (s.t.) in H107, Fakultät für Physik, LMU

Alexej Streltsov,...

CONTACT

Max-Planck-Institut für Quantenoptik 

Hans-Kopfermann-Str. 1
85748 Garching, Germany 

Phone: +49 (0)89 32905 - 138 
Fax: +49 (0)89 32905 - 313

Kristina Schuldt

Ludwig-Maximilians-University
Quantum Optics Chair/
Fakultät für Physik 

Schellingstr. 4
80799 Munich, Germany

Phone: +49 (0)89 2180 - 6131
Fax: +49 (0)89 2180 - 63850

Ildiko Kecskesi