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 of Quantum Optics and the Ludwig Maximilians University. Furthermore, our group is part of the Munich Quantum Center.

We are always looking for Master students, PhD students and Postdocs. For more information click here! 

Using spin-resolved quantum gas microscopy, we directly observed two fundamental predictions for Luttinger liquids, a theory which generically describes gapless 1d systems including the doped Fermi-Hubbard model studied here. We detected a linear variation of the spin-density wave vector as a function of doping in good agreement with quantum Monte-Carlo calculations at T/t=0.29. The microscopic origin of this phenomenon was attributed to the dilution of antiferromagnetic correlations by holes and doublons acting as domain walls. When studying spin-imbalanced clouds in squeezed space, we observed a linear increase of the spin-density wave vector with polarization in excellent agreement with exact diagonalization calculations of the Heisenberg model. This wavelength extension was attributed microscopically to pairs of parallel spins acting as domain walls for the antiferromagnetic order. Finally, when inducing interchain coupling to map out spin correlations in the crossover regime, we observed fundamentally different spin correlations in the direct vicinity of doublons in 2d, suggesting the formation of a magnetic polaron.

https://www.nature.com/articles/s41586-018-0778-7

In this work we study ultracold polar molecules with long-range interactions over extended periods of time using a „supermagic“ trapping technique. To obtain the interacting molecular gas we create a superposition of the molecules’ ground and first excited rotational states. In general, these two states react differently to the optical trap holding the molecules. The couplings between nuclear spins, rotation and the trap light lead to a Gordian knot of transitions in the rotation spectra. This masks the observation of the collective molecular spin dynamics. In this work we disentangle the spectra using two tricks: A special, so-called „magic“ polarization of the trap beam and a small static electric field. In this supermagic trap we can then expose the dipolar interactions between the molecules. This paves the way towards the simulation of complex quantum models with long-range interactions, e.g. to explore superconducting materials.

PhysRevLett.121.253401 (2018)

To spread the word about the fascinating physics behind ultracold polar molecules, Frauke loves to travel to Science Slams all over Germany. There the goal is to present own research to a general audience in 10 minutes. Ideally in an understandable and entertaining way, because in the end the audience is also the jury of all performances. Now you can watch her performance from 19th of September 2018 in Ulm on YouTube and learn about her molecular dating agency “alkaLiebe

We experimentally and numerically investigate mass transport of fermions in a one-dimensional optical lattice by releasing an initially trapped gas suddenly into a homogeneous potential landscape. For initial states with an appreciable amount of doublons, we observe a dynamical phase separation between rapidly expanding singlons and slow doublons remaining in the trap center, realizing the key aspect of fermionic quantum distillation in the strongly-interacting limit. For initial states without doublons, we find a reduced interaction dependence of the asymptotic expansion speed compared to bosons, which is explained in terms of the interaction energy produced by dynamically generated doublons in the interaction quench.

Phys. Rev. Lett. 121, 130402 (2018)

Breaking down our research so that 99,999% of the worlds population would understand it, was the goal of Jayadev Vijayan with his article "Zooming into superconducters". With his Leap - a popular science article on quantum research written by scientists and reviewed by teenagers — published in Quantum Views, he explains his research to 13-14 year old High School students who reviewed the article and (hopefully!) understood why cold atoms is a research field worth studying.

See yourself if you understand Jayadevs explanation: HERE
Learn more about Quantum Leaps on the Quantum Journal website.

SEMINARS

Special Group Seminar at MPQ: Superfluid transport through an optical lattice over a macroscopic distance

Thursday, 28th March, 2019, 10:00 am at MPQ temporary lecture hall Andreas Schindewolf, ...

Group Seminar at LMU: Staggered-immersion cooling of a quantum gas in optical lattices

Tuesday, 19th March 2019, 9:15am at LMU, seminar room H107 Bing Yang from the University of...