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

The symposium, which is open to the public, will take place in the Große Aula of LMU in Munich on 18-19 November 2016. For the symposium we were able to invite a great line-up of speakers from all over the world, among them three Nobel Prize winners. All of the speakers share a special relation to Ted Hänsch and next to scientific advancements will give us a glimpse on how Ted Hänsch has influenced their own work. In case you plan on coming, please register (free) here, as this will help us to estimate the number of participants. We are looking forward to welcoming as many of you as possible at these festivities!


In Fermi-Hubbard systems, a great challenge is to reach sufficiently low entropies to observe spin correlations. Extending our Fermi gas microscope on spin resolution, we achieved single-atom and spin resolved detection of spin-1/2 Hubbard chains with entropies down to s= 0.5 kB, supporting antiferromagnetic correlations up to three sites. Our simultaneous detection of spins and on-site densities opens the route to study the influence of doping on magnetic ordering.

Science, DOI: 10.1126/science.aag1635

Pressrelease: English, Deutsch

Long-range interacting many-body systems differ fundamentally from their short-range counterparts. Creating a laser-controlled superposition with a highly excited and strongly interacting Rydberg state, we recently succeeded in implementing a novel kind of long-range interaction between microscopic atomic magnets. Control over the range, isotropy and sign of the interaction was demonstrated by an interferometric measurement technique, laying the basis for future studies of many-body spin systems.

Nature Physics, Doi:10.1038/nphys3835

Press release: English Deutsch

Almost all quantum systems thermalize after being brought out of equilibrium initially. Many-body localization is a prominent counterexample in which localization hinders thermalization, even at high energies. Recently, we observed the localization transition in two dimensions with bosonic atoms in a disordered optical lattice. Through a single atom resolved study of the dynamics, we identified a thermalized and a localized phase and inferred a critical disorder for the phase transition.

Science 352, 1547 (2016).

Press release: English Deutsch

 You are a Master student and considering doing your research thesis in experimental quantum physics?

• Learn about state-of-the-art research in quantum gases
• Understand what a quantum simulator does
• Discuss with leading researchers and students
• Learn about precision lasers, ultrahigh vacuum, electronics and more
• See how it's done: visit our labs at MPQ!

The Mott metal-to-insulator transition is a prominent phenomenon in condensed matter physics. We have used ytterbium atoms in an optical lattice to realize an extended-symmetry SU(N) Mott insulator, taking a direct look into this transition to better understand fermionic many-body systems.

Phys. Rev. X 6, 021030 (2016)

The geometric and topological structure of energy bands play an important role in modern condensed matter physics but are difficult to experimentally access. Using ultracold bosons in a honeycomb lattice, we demonstrate a straight-forward method that can be used to both reconstruct the Bloch states at every quasimomentum and determine the topological invariants of the bands. Our method is based on using strong-force dynamics to realize a system that can be described by Wilson lines.

Science 352, 1094 (2016)

Press release: English Deutsch

The phenomenon of Many-Body Localization (MBL) presents a generic alternative to thermalization in isolated quantum systems. Using ultracold fermions we study the effect of coupling identically disordered MBL systems with each other and ask - "Can these localized systems collectively serve as a bath for one-another and delocalize the entire system?" We find that MBL is indeed unstable to such a coupling and generically delocalizes. Further, we find that the behavior is strikingly different from Anderson Localization, which remains stable to such a coupling.

Phys. Rev. Lett. 116, 140401 (2016)