Ultracold
fermion mixtures with tunable interactions:
polarons and the quest for novel
superfluids
Rudolf Grimm
Univ. of
Innsbruck and IQOQI,
Austrian Academy of Sciences
Abstract:
The possibility to tune interatomic
interactions by means of magnetically controlled Feshbach
resonances has opened
up unprecedented opportunities for experiments concerning the
intriguing
many-body physics of ultracold matter in the strongly interacting
regime. After
a brief general introduction, I will report on two main research
lines pursued
in our laboratories based on fermionic quantum mixtures with
tunable
interactions.
(1) A Fermi sea of Li-6 atoms is doped with
impurity atoms of fermionic K-40 or bosonic K-41 atoms, which
under strong
interactions form quasiparticles. We explore the various
properties of these
“Fermi polarons” by means of radio-frequency spectroscopy. In our
most recent
experiments [1], we have observed mediated interactions between
the polarons,
with the surprising finding that the sign of the interaction
depends on the
quantum statistics of the impurity atoms.
(2) In a Fermi-Fermi mixture of Dy-161 and
K-40, we are proceeding towards the creation of novel imbalanced
fermion
superfluids. After exploring the complex spectrum of Feshbach
resonances, we
have studied the spectrum of collective modes in the deep
hydrodynamic regime and
we have demonstrated the magneto-association of ultracold bosonic
molecules
under conditions near quantum degeneracy [2].
[1]
C. Baroni, I.
Fritsche, E. Dobler, G.
Anich, E. Kirilov, R. Grimm, M. A. Bastarrachea-Magnani,
P. Massignan, G. Bruun, Nat. Phys. (2023).
[2] E.
Soave,
A. Canali, Z.-X. Ye, M. Kreyer, E. Kirilov, R. Grimm, Phys. Rev.
Research 5,
033117 (2023).
Short biography: 1986 Diploma,
Univ. of Hannover, Germany 1989 PhD, ETH
Zurich, Switzerland 1989 – 1990:
Postdoc at the Inst. of Spectroscopy, Troitsk, USSR 1990 – 2000:
Researcher at the MPI for Nuclear Physics, Heidelberg, Germany 2000 – now:
Professor of Experimental Physics, Innsbruck, Austria 2003 – now:
Scientific Director at IQOQI Innsbruck, Austria
Major Awards / Honors: 2005 Wittgenstein
Award (Austrian Science Fund and Federal Ministry) 2006 Elected Full
Member of the Austrian Acad. of Sciences 2008 Science
Prize of the State of Tyrol 2018 Faddeev
Medal 2021 ERC Advanced
Grant 2022 Toptica BEC
Senior Award