677 research outputs found
Synthetic dimensions in ultracold molecules: quantum strings and membranes
Synthetic dimensions alter one of the most fundamental properties in nature,
the dimension of space. They allow, for example, a real three-dimensional
system to act as effectively four-dimensional. Driven by such possibilities,
synthetic dimensions have been engineered in ongoing experiments with ultracold
matter. We show that rotational states of ultracold molecules can be used as
synthetic dimensions extending to many - potentially hundreds of - synthetic
lattice sites. Microwaves coupling rotational states drive fully controllable
synthetic inter-site tunnelings, enabling, for example, topological band
structures. Interactions leads to even richer behavior: when molecules are
frozen in a real space lattice with uniform synthetic tunnelings, dipole
interactions cause the molecules to aggregate to a narrow strip in the
synthetic direction beyond a critical interaction strength, resulting in a
quantum string or a membrane, with an emergent condensate that lives on this
string or membrane. All these phases can be detected using measurements of
rotational state populations.Comment: 5-page article + 4 figures + references; 7 pages + 4 figures in
Supplemen
Correlations and enlarged superconducting phase of - chains of ultracold molecules on optical lattices
We compute physical properties across the phase diagram of the -
chain with long-range dipolar interactions, which describe ultracold polar
molecules on optical lattices. Our results obtained by the density-matrix
renormalization group (DMRG) indicate that superconductivity is enhanced when
the Ising component of the spin-spin interaction and the charge component
are tuned to zero, and even further by the long-range dipolar interactions.
At low densities, a substantially larger spin gap is obtained. We provide
evidence that long-range interactions lead to algebraically decaying
correlation functions despite the presence of a gap. Although this has recently
been observed in other long-range interacting spin and fermion models, the
correlations in our case have the peculiar property of having a small and
continuously varying exponent. We construct simple analytic models and
arguments to understand the most salient features.Comment: published version with minor modification
Accessing Rydberg-dressed interactions using many-body Ramsey dynamics
We demonstrate that Ramsey spectroscopy can be used to observe
Rydberg-dressed interactions. In contrast to many prior proposals, our scheme
operates comfortably within experimentally measured lifetimes, and accesses a
regime where quantum superpositions are crucial. The key idea is to build a
spin-1/2 from one level that is Rydberg-dressed and another that is not. These
levels may be hyperfine or long-lived electronic states. An Ising spin model
governs the Ramsey dynamics, for which we derive an exact solution. Due to the
structure of Rydberg interactions, the dynamics differs significantly from that
in other spin systems. As one example, spin echo can increase the rate at which
coherence decays. The results also apply to bare (undressed) Rydberg states as
a special case, for which we quantitatively reproduce recent ultrafast
experiments without fitting
A Model for Scattering with Proliferating Resonances: Many Coupled Square Wells
We present a multichannel model for elastic interactions, comprised of an
arbitrary number of coupled finite square-well potentials, and derive
semi-analytic solutions for its scattering behavior. Despite the model's
simplicity, it is flexible enough to include many coupled short-ranged
resonances in the vicinity of the collision threshold, as is necessary to
describe ongoing experiments in ultracold molecules and lanthanide atoms. We
also introduce a simple, but physically realistic, statistical ensemble for
parameters in this model. We compute the resulting probability distributions of
nearest-neighbor resonance spacings and analyze them by fitting to the Brody
distribution. We quantify the ability of alternative distribution functions,
for resonance spacing and resonance number variance, to describe the crossover
regime. The analysis demonstrates that the multichannel square-well model with
the chosen ensemble of parameters naturally captures the crossover from
integrable to chaotic scattering as a function of closed channel coupling
strength.Comment: 11 pages, 8 figure
Stirring trapped atoms into fractional quantum Hall puddles
We theoretically explore the generation of few-body analogs of fractional
quantum Hall states. We consider an array of identical few-atom clusters
(n=2,3,4), each cluster trapped at the node of an optical lattice. By
temporally varying the amplitude and phase of the trapping lasers, one can
introduce a rotating deformation at each site. We analyze protocols for
coherently transferring ground state clusters into highly correlated states,
producing theoretical fidelities in excess of 99%.Comment: 4 pages, 3 figures (13 subfigures) -- v2: published versio
Surveys For Rare and Endangered Mussel Species In Kansas: Traditional Methods and Environmental DNA Analysis
The Mucket (Actinonaias ligamentina) is one of the rarest freshwater mussel species in the state of Kansas. It historically occurred in the Kansas and Osage River systems in the state. The Mucket has been extirpated from most streams and rivers in Kansas where it historically occurred, and few specimens have been documented in recent years. The objective of my project was to determine the conservation status of the Mucket by conducting qualitative surveys in the Osage River system of eastern Kansas. My goals were to collect information that will aid in the recovery of the Mucket and to provide information regarding the mussel communities in these streams. During the summer of 2016, I surveyed 14 sites on the Marais des Cygnes River, 5 sites on Pottawatomie Creek, and 4 sites on the Marmaton River. I collected one live Mucket on Pottawatomie Creek. During the course of the survey, I collected 2,993 live mussels representing 19 species
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