Citation for published item:kekoshiD etsu nd eihs¤ ollnerD vuks nd hindewolfD endres nd rutsonD teremy wF nd ve ueurD gF uth nd hulieuD ylivier nd perlinoD prnes nd qrimmD udolf nd x¤ gerlD rnnsEghristoph @PHIRA 9ltrold dense smples of dipolr gs moleules in the rovirtionl nd hyper(ne ground stteF9D hysil review lettersFD IIQ F pF PHSQHIF Further information on publisher's website: eprinted with permission from the emerin hysil oietyX etsu kekoshiD vuks eihs¤ ollnerD endres hindewolfD teremy wF rutsonD gF uth ve ueurD ylivier hulieuD prnes perlinoD udolf qrimmD nd rnnsEghristoph x¤ gerl @PHIRA 9ltrold dense smples of dipolr gs moleules in the rovirtionl nd hyper(ne ground stteF9D hysil review lettersFD IIQ F pF PHSQHIF PHIR y the emerin hysil oietyF eders my viewD rowseD ndGor downlod mteril for temporry opying purposes onlyD provided these uses re for nonommeril personl purposesF ixept s provided y lwD this mteril my not e further reproduedD distriutedD trnsmittedD modi(edD dptedD performedD displyedD pulishedD or sold in whole or prtD without prior written permission from the emerin hysil oietyF Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

We report on the observation of confinement-induced resonances in strongly interacting quantum-gas systems with tunable interactions for one- and two-dimensional geometry. Atom-atom scattering is substantially modified when the s-wave scattering length approaches the length scale associated with the tight transversal confinement, leading to characteristic loss and heating signatures. Upon introducing an anisotropy for the transversal confinement we observe a splitting of the confinement-induced resonance. With increasing anisotropy additional resonances appear. In the limit of a two-dimensional system we find that one resonance persists.

Quantum many-body systems can have phase transitions even at zero temperature; fluctuations arising from Heisenberg's uncertainty principle, as opposed to thermal effects, drive the system from one phase to another. Typically, during the transition the relative strength of two competing terms in the system's Hamiltonian changes across a finite critical value. A well-known example is the Mott-Hubbard quantum phase transition from a superfluid to an insulating phase, which has been observed for weakly interacting bosonic atomic gases. However, for strongly interacting quantum systems confined to lower-dimensional geometry, a novel type of quantum phase transition may be induced and driven by an arbitrarily weak perturbation to the Hamiltonian. Here we observe such an effect--the sine-Gordon quantum phase transition from a superfluid Luttinger liquid to a Mott insulator--in a one-dimensional quantum gas of bosonic caesium atoms with tunable interactions. For sufficiently strong interactions, the transition is induced by adding an arbitrarily weak optical lattice commensurate with the atomic granularity, which leads to immediate pinning of the atoms. We map out the phase diagram and find that our measurements in the strongly interacting regime agree well with a quantum field description based on the exactly solvable sine-Gordon model. We trace the phase boundary all the way to the weakly interacting regime, where we find good agreement with the predictions of the one-dimensional Bose-Hubbard model. Our results open up the experimental study of quantum phase transitions, criticality and transport phenomena beyond Hubbard-type models in the context of ultracold gases.

Particles in a perfect lattice potential perform Bloch oscillations when subject to a constant force, leading to localization and preventing conductivity. For a weakly interacting Bose-Einstein condensate of Cs atoms, we observe giant center-of-mass oscillations in position space with a displacement across hundreds of lattice sites when we add a periodic modulation to the force near the Bloch frequency. We study the dependence of these "super" Bloch oscillations on lattice depth, modulation amplitude, and modulation frequency and show that they provide a means to induce linear transport in a dissipation-free lattice.

We perform one-and two-photon high resolution spectroscopy on ultracold samples of RbCs Feshbach molecules with the aim to identify a suitable route for efficient ground-state transfer in the quantum-gas regime to produce quantum gases of dipolar RbCs ground-state molecules. One-photon loss spectroscopy allows us to probe deeply bound rovibrational levels of the mixed excited (A 1 Σ + − b 3 Π 0 ) 0 + molecular states. Two-photon dark state spectroscopy connects the initial Feshbach state to the rovibronic ground state. We determine the binding energy of the lowest rovibrational level |v ′′ = 0, J ′′ = 0 of the X 1 Σ + ground state to be D X 0 = 3811.5755(16) cm −1 , a 300-fold improvement in accuracy with respect to previous data. We are now in the position to perform stimulated two-photon Raman transfer to the rovibronic ground state.