9 research outputs found
Observation of heteronuclear atomic Efimov resonances
The Efimov effect represents a cornerstone in few-body physics. Building on
the recent experimental observation with ultracold atoms, we report the first
experimental signature of Efimov physics in a heteronuclear system. A mixture
of K and Rb atoms was cooled to few hundred nanoKelvins and
stored in an optical dipole trap. Exploiting a broad interspecies Feshbach
resonance, the losses due to three-body collisions were studied as a function
of the interspecies scattering length. We observe an enhancement of the
three-body collisions for three distinct values of the interspecies scattering
lengths, both positive and negative. We attribute the two features at negative
scattering length to the existence of two kind of Efimov trimers, namely KKRb
and KRbRb.Comment: 4 pages, 4 figure
Collisional and molecular spectroscopy in an ultracold Bose-Bose mixture
The route toward a Bose-Einstein condensate of dipolar molecules requires the
ability to efficiently associate dimers of different chemical species and
transfer them to the stable rovibrational ground state. Here, we report on
recent spectroscopic measurements of two weakly bound molecular levels and
newly observed narrow d-wave Feshbach resonances. The data are used to improve
the collisional model for the Bose-Bose mixture 41K87Rb, among the most
promising candidates to create a molecular dipolar BEC.Comment: 13 pages, 3 figure
Entropy exchange in a mixture of ultracold atoms
We investigate experimentally the entropy transfer between two
distinguishable atomic quantum gases at ultralow temperatures. Exploiting a
species-selective trapping potential, we are able to control the entropy of one
target gas in presence of a second auxiliary gas. With this method, we drive
the target gas into the degenerate regime in conditions of controlled
temperature by transferring entropy to the auxiliary gas. We envision that our
method could be useful both to achieve the low entropies required to realize
new quantum phases and to measure the temperature of atoms in deep optical
lattices. We verified the thermalization of the two species in a 1D lattice.Comment: 5 pages, 4 figure
Observation of Heteronuclear Atomic Efimov Resonances
Building on the recent experimental observation with ultracold atoms, we report the first experimental evidence of Efimov physics in a heteronuclear system. A mixture of (41)K and (87)Rb atoms was cooled to few hundred nanokelvins and stored in an optical dipole trap. Exploiting a broad interspecies Feshbach resonance, the losses due to three-body collisions were studied as a function of the interspecies scattering length. We observe an enhancement of the three-body collisions for three distinct values of the interspecies scattering lengths, both positive and negative, where no Feshbach resonances are expected. We attribute the two features at negative scattering length to the existence of two kinds of Efimov trimers, KKRb and KRbRb
Collisional and molecular spectroscopy in an ultracold Bose-Bose mixture
The route towards a Bose-Einstein condensate (BEC) of dipolar molecules requires the ability to efficiently associate dimers of different chemical species and transfer them to the stable rovibrational ground state. Here, we report on recent spectroscopic measurements of two weakly bound molecular levels and newly observed narrow d-wave Feshbach resonances. The data are used to improve the collisional model for the Bose-Bose mixture (KRb)-K-41-Rb-87, one of the most promising candidates to create a molecular dipolar BEC