We report on the first realization of heteronuclear dipolar quantum mixtures of highly magnetic erbium and dysprosium atoms. With a versatile experimental setup, we demonstrate binary Bose-Einstein ...condensation in five different Er-Dy isotope combinations, as well as one Er-Dy Bose-Fermi mixture. Finally, we present first studies of the interspecies interaction between the two species for one mixture.
A supersolid is a counterintuitive phase of matter that combines the global phase coherence of a superfluid with a crystal-like self-modulation in space. Recently, such states have been ...experimentally realized using dipolar quantum gases. Here we investigate the response of a dipolar supersolid to an interaction quench that shatters the global phase coherence. We identify a parameter regime in which this out-of-equilibrium state rephases, indicating superfluid flow across the sample as well as an efficient dissipation mechanism. We find a crossover to a regime where the tendency to rephase gradually decreases until the system relaxes into an incoherent droplet array. Although a dipolar supersolid is, by its nature, ‘soft’, we capture the essential behaviour of the de- and rephasing process within a rigid Josephson junction array model. Yet, both experiment and simulation indicate that the interaction quench causes substantial collective mode excitations that connect to phonons in solids and affect the phase dynamics.A supersolid is a phase of matter featuring both crystalline order as a solid and global phase coherence as a superfluid. Now an experiment shows how this global phase coherence can be established across the system in a non-equilibrium process.
By combining theory and experiments, we demonstrate that dipolar quantum gases of bothEr166andDy164support a state with supersolid properties, where a spontaneous density modulation and a global ...phase coherence coexist. This paradoxical state occurs in a well-defined parameter range, separating the phases of a regular Bose-Einstein condensate and of an insulating droplet array, and is rooted in the roton mode softening, on the one side, and in the stabilization driven by quantum fluctuations, on the other side. Here, we identify the parameter regime for each of the three phases. In the experiment, we rely on a detailed analysis of the interference patterns resulting from the free expansion of the gas, quantifying both its density modulation and its global phase coherence. Reaching the phases via a slow interaction tuning, starting from a stable condensate, we observe thatEr166andDy164exhibit a striking difference in the lifetime of the supersolid properties, due to the different atom loss rates in the two systems. Indeed, while inEr166the supersolid behavior survives only a few tens of milliseconds, we observe coherent density modulations for more than 150 ms inDy164. Building on this long lifetime, we demonstrate an alternative path to reach the supersolid regime, relying solely on evaporative cooling starting from a thermal gas.
Alignment of D-state Rydberg molecules Krupp, A T; Gaj, A; Balewski, J B ...
Physical review letters,
04/2014, Letnik:
112, Številka:
14
Journal Article
Recenzirano
Odprti dostop
We report on the formation of ultralong-range Rydberg D-state molecules via photoassociation in an ultracold cloud of rubidium atoms. By applying a magnetic offset field on the order of 10 G and high ...resolution spectroscopy, we are able to resolve individual rovibrational molecular states. A full theory, using a Fermi pseudopotential approach including s- and p-wave scattering terms, reproduces the measured binding energies. The calculated molecular wave functions show that in the experiment we can selectively excite stationary molecular states with an extraordinary degree of alignment or antialignment with respect to the magnetic field axis.
The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between a Rydberg electron and a polarizable ground-state atom in an ultracold gas. In the nondegenerate ...case, the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.
We present a study of the Rydberg spectrum in ^{166}Er for series connected to the 4f^{12}(^{3}H_{6})6s, J_{c}=13/2, and J_{c}=11/2 ionic core states using an all-optical detection based on ...electromagnetically induced transparency in an effusive atomic beam. Identifying approximately 550 individual states, we find good agreement with a multichannel quantum defect theory (MQDT) which allows assignment of most states to ns or nd Rydberg series. We provide an improved accuracy for the lowest two ionization thresholds to E_{IP,J_{c}=13/2}=49260.750(1)cm^{−1} and E_{IP,J_{c}=11/2}=49701.184(1)cm^{−1} as well as the corresponding quantum defects for all observed series. We identify Rydberg states in five different isotopes, and states between the two lowest ionization thresholds. Our results open the way for future applications of Rydberg states for quantum simulation using erbium and exploiting its special open-shell structure.
We experimentally and theoretically investigate the influence of the dipole-dipole interactions (DDIs) on the total inter-species interaction in an erbium-dysprosium mixture. By rotating the dipole ...orientation we are able to tune the effect of the long-range and anisotropic DDI, and therefore the in-trap clouds displacement. We present a theoretical description for our binary system based on an extended Gross-Pitaevskii (eGP) theory, including the single-species beyond mean-field terms, and we predict a lower and an upper bound for the inter-species scattering length \(a_{12}\). Our work is a first step towards the investigation of the experimentally unexplored dipolar miscibility-immiscibility phase diagram and the realization of quantum droplets and supersolid states with heteronuclear dipolar mixtures.
We present a study of the Rydberg spectrum in \ts{166}Er for series connected to the \(4f^{12} (^3H_6) 6s\), \(J_c=13/2 \) and \(J_c=11/2 \) ionic core states using an all-optical detection based on ...electromagnetically induced transparency in an effusive atomic beam. Identifying approximately 550 individual states, we find good agreement with a multi-channel quantum defect theory (MQDT) which allows assignment of most states to \(ns\) or \(nd\) Rydberg series. We provide an improved accuracy for the lowest two ionization thresholds to \(E_{\textrm{IP}, J_c = 13/2 } = 49260.750(1)\,\)cm\(^{-1}\) and \(E_{\textrm{IP}, J_c = 11/2 } = 49701.184(1)\,\)cm\(^{-1}\) as well as the corresponding quantum defects for all observed series. We identify Rydberg states in five different isotopes, and states between the two lowest ionization thresholds. Our results open the way for future applications of Rydberg states for quantum simulation using erbium and exploiting its special open-shell structure.
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