Strongly interacting Rydberg atoms in synthetic dimensions with a magnetic flux.

Synthetic dimensions, wherein dynamics occurs in a set of internal states, have found great success in recent years in exploring topological effects in cold atoms and photonics. However, the phenomena thus far explored have largely been restricted to the non-interacting or weakly interacting regimes. Here, we extend the synthetic dimensions playbook to strongly interacting systems of Rydberg atoms prepared in optical tweezer arrays. We use precise control over driving microwave fields to introduce a tunable U(1) flux in a four-site lattice of coupled Rydberg levels. We find highly coherent dynamics, in good agreement with theory. Single atoms show oscillatory dynamics controllable by the gauge field. Small arrays of interacting atoms exhibit behavior suggestive of the emergence of ergodic and arrested dynamics in the regimes of intermediate and strong interactions, respectively. These demonstrations pave the way for future explorations of strongly interacting dynamics and many-body phases in Rydberg synthetic lattices.

Influence of Colorectal Cancer Risk Factors on Predictive Value of a Positive Multitarget Stool DNA Test.

GOALS: We analyzed if the predictive value of multitarget stool-based DNA (mt-sDNA) varied when patients had pre-existing known colorectal cancer (CRC) risk factors. BACKGROUND: mt-sDNA test is approved for CRC screening in average-risk patients. Whether patients with a personal history of adenomatous colon polyps or a family history of CRC (CRC risk factors) benefit from mt-sDNA testing is unknown. STUDY: We reviewed charts for all positive mt-sDNA referrals between 2017 and 2021. Diagnostic colonoscopy adherence rates were calculated. In those who had colonoscopy, we compared detection rates for any colorectal neoplasia (CRN), multiple (3 or more) adenomas, sessile serrated polyps (SSP), advanced CRN, and CRC between patients with and without known CRC risk factors. RESULTS: Of 1297 referrals for positive mt-sDNA, 1176 (91%) completed a diagnostic colonoscopy. The absence of neoplasia was noted in 27% of colonoscopy exams. When neoplasia was identified, findings were as follows: any CRN (73%), multiple adenomas (34%), SSP (23%), advanced CRN (33%), and CRC (2.5%). One or more CRC risk factors were present in 229 (19%) of cases. In the CRC risk factor subgroup, patients having a prior history of adenomatous polyps or a family history of CRC were no more likely to have any CRN, multiple adenomas, SSP, advanced CRN, or CRC compared to average-risk patients when mt-sDNA was positive. CONCLUSIONS: In this real-world analysis of positive mt-sDNA referrals, adherence to subsequent diagnostic colonoscopy recommendations was high. The presence of pre-existing CRC risk factors did not affect the positive predictive value of mt-sDNA.

Two-Dimensional Programmable Tweezer Arrays of Fermions.

We prepare high-filling two-component arrays of tens of fermionic ^{6}Li atoms in optical tweezers, with the atoms in the ground motional state of each tweezer. Using a stroboscopic technique, we configure the arrays in various two-dimensional geometries with negligible Floquet heating. A full spin- and density-resolved readout of individual sites allows us to postselect near-zero entropy initial states for fermionic quantum simulation. We prepare a correlated state in a two-by-two tunnel-coupled Hubbard plaquette, demonstrating all the building blocks for realizing a programmable fermionic quantum simulator.

Nonlinear Dynamics in a Synthetic Momentum-State Lattice.

The scope of analog simulation in atomic, molecular, and optical systems has expanded greatly over the past decades. Recently, the idea of synthetic dimensions-in which transport occurs in a space spanned by internal or motional states coupled by field-driven transitions-has played a key role in this expansion. While approaches based on synthetic dimensions have led to rapid advances in single-particle Hamiltonian engineering, strong interaction effects have been conspicuously absent from most synthetic dimensions platforms. Here, in a lattice of coupled atomic momentum states, we show that atomic interactions result in large and qualitative changes to dynamics in the synthetic dimension. We explore how the interplay of nonlinear interactions and coherent tunneling enriches the dynamics of a one-band tight-binding model giving rise to macroscopic self-trapping and phase-driven Josephson dynamics with a nonsinusoidal current-phase relationship, which can be viewed as stemming from a nonlinear band structure arising from interactions.

Synthetic dimensions in ultracold polar molecules.

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 local measurements of rotational state populations.

Accessory genetic content in Campylobacter jejuni ST21CC isolates from feces and blood.

Campylobacter jejuni is an important foodborne pathogen and the most commonly reported bacterial cause of gastroenteritis. C. jejuni is occasionally found in blood, although mechanisms important for invasiveness have remained unclear. C. jejuni is divided into many different lineages, of which the ST21 clonal complex (CC) is widely distributed. Here, we performed comparative genomic and in vitro analyses on 17C. jejuni ST21CC strains derived from human blood and feces in order to identify features associated with isolation site. The ST21CC lineage is divided into two large groups; centered around ST-21 and ST-50. Our clinical strains, typed as ST-50, showed further microevolution into two distinct clusters. These clusters were distinguished by major differences in their capsule loci and the distribution of accessory genetic content, including C. jejuni integrated elements (CJIEs) and plasmids. Accessory genetic content was more common among fecal than blood strains, whereas blood strains contained a hybrid capsule locus which partially consisted of C. jejuni subsp. doylei-like content. In vitro infection assays with human colon cell lines did not show significant differences in adherence and invasion between the blood and fecal strains. Our results showed that CJIEs and plasmid derived genetic material were less common among blood isolates than fecal isolates; in contrast, hybrid capsule loci, especially those containing C. jejuni subsp. doylei-like gene content, were found among many isolates derived from blood. The role of these findings requires more detailed investigation.

First case of human bacteraemia by Catabacter hongkongensis in Scandinavia.

Catabacter hongkongensis was isolated and cultured from human blood for the first time in Scandinavia. The patient, an 83-year-old man from Dalarna, Sweden, recovered without antibiotic treatment, although a high mortality rate associated with C. hongkongensis infection had been reported from China, Canada and France. The genome of the strain ABBA15k was sequenced, assembled and analysed. In contrast to the type strain of the species HKU16T, no antibiotic resistance was observed in Scandinavian strain ABBA15k. The strain was deposited as CCUG 68271, and the draft genome sequence is available from the DNA Data Bank of Japan (DDBJ), the European Molecular Biology Laboratory (EMBL), and GenBank under the accession number LLYX00000000.

Ultracold Nonreactive Molecules in an Optical Lattice: Connecting Chemistry to Many-Body Physics.

We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice, analogous to the Hubbard model that describes ultracold atoms in a lattice. In stark contrast to the Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multichannel interaction, whose properties we elucidate. Because this arises from complex short-range collisional physics, it requires no dipolar interactions and thus occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We show that the effective model parameters can be determined in lattice modulation experiments, which, consequently, measure molecular collision dynamics with a vastly sharper energy resolution than experiments in a free-space ultracold gas.

Many-body dynamics of dipolar molecules in an optical lattice.

We use Ramsey spectroscopy to experimentally probe the quantum dynamics of disordered dipolar-interacting ultracold molecules in a partially filled optical lattice, and we compare the results to theory. We report the capability to control the dipolar interaction strength. We find excellent agreement between our measurements of the spin dynamics and theoretical calculations with no fitting parameters, including the dynamics' dependence on molecule number and on the dipolar interaction strength. This agreement verifies the microscopic model expected to govern the dynamics of dipolar molecules, even in this strongly correlated beyond-mean-field regime, and represents the first step towards using this system to explore many-body dynamics in regimes that are inaccessible to current theoretical techniques.

Observation of dipolar spin-exchange interactions with lattice-confined polar molecules.

With the production of polar molecules in the quantum regime, long-range dipolar interactions are expected to facilitate understanding of strongly interacting many-body quantum systems and to realize lattice spin models for exploring quantum magnetism. In ordinary atomic systems, where contact interactions require wavefunction overlap, effective spin interactions on a lattice can be mediated by tunnelling, through a process referred to as superexchange; however, the coupling is relatively weak and is limited to nearest-neighbour interactions. In contrast, dipolar interactions exist even in the absence of tunnelling and extend beyond nearest neighbours. This allows coherent spin dynamics to persist even for gases with relatively high entropy and low lattice filling. Measured effects of dipolar interactions in ultracold molecular gases have been limited to the modification of inelastic collisions and chemical reactions. Here we use dipolar interactions of polar molecules pinned in a three-dimensional optical lattice to realize a lattice spin model. Spin is encoded in rotational states of molecules that are prepared and probed by microwaves. Resonant exchange of rotational angular momentum between two molecules realizes a spin-exchange interaction. The dipolar interactions are apparent in the evolution of the spin coherence, which shows oscillations in addition to an overall decay of the coherence. The frequency of these oscillations, the strong dependence of the spin coherence time on the lattice filling factor and the effect of a multipulse sequence designed to reverse dynamics due to two-body exchange interactions all provide evidence of dipolar interactions. Furthermore, we demonstrate the suppression of loss in weak lattices due to a continuous quantum Zeno mechanism. Measurements of these tunnelling-induced losses allow us to determine the lattice filling factor independently. Our work constitutes an initial exploration of the behaviour of many-body spin models with direct, long-range spin interactions and lays the groundwork for future studies of many-body dynamics in spin lattices.

Far-from-equilibrium quantum magnetism with ultracold polar molecules.

Recent theory has indicated how to emulate tunable models of quantum magnetism with ultracold polar molecules. Here we show that present molecule optical lattice experiments can accomplish three crucial goals for quantum emulation, despite currently being well below unit filling and not quantum degenerate. The first is to verify and benchmark the models proposed to describe these systems. The second is to prepare correlated and possibly useful states in well-understood regimes. The third is to explore many-body physics inaccessible to existing theoretical techniques. Our proposal relies on a nonequilibrium protocol that can be viewed either as Ramsey spectroscopy or an interaction quench. The proposal uses only routine experimental tools available in any ultracold molecule experiment. To obtain a global understanding of the behavior, we treat short times pertubatively, develop analytic techniques to treat the Ising interaction limit, and apply a time-dependent density matrix renormalization group to disordered systems with long range interactions.

Adiabatic loading of one-dimensional SU(N) alkaline-earth-atom fermions in optical lattices.

Ultracold fermionic alkaline earth atoms confined in optical lattices realize Hubbard models with internal SU(N) symmetries, where N can be as large as ten. Such systems are expected to harbor exotic magnetic physics at temperatures below the superexchange energy scale. Employing quantum Monte Carlo simulations to access the low-temperature regime of one-dimensional chains, we show that after adiabatically loading a weakly interacting gas into the strongly interacting regime of an optical lattice, the final temperature decreases with increasing N. Furthermore, we estimate the temperature scale required to probe correlations associated with low-temperature SU(N) magnetism. Our findings are encouraging for the exploration of exotic large-N magnetic states in ongoing experiments.

Local versus global equilibration near the bosonic Mott-insulator-superfluid transition.

We study the time scales for adiabaticity of trapped cold bosons subject to a time-varying lattice potential using a dynamic Gutzwiller mean-field theory. We explain apparently contradictory experimental observations by demonstrating a clear separation of time scales for local dynamics (~ ms) and global mass redistribution (~1 s). We provide a simple explanation for the short and fast time scales, finding that while density or energy transport is dominated by low energy phonons, particle-hole excitations set the adiabaticity time for fast ramps. We show how mass transport shuts off within Mott-insulator domains, leading to a chemical potential gradient that fails to equilibrate on experimental time scales.

Influence of film-mediated interactions on the microwave and radio frequency spectrum of spin-polarized hydrogen on helium films.

We argue that helium film-mediated hydrogen-hydrogen interactions strongly reduce the magnitude of cold collision shifts in spin-polarized hydrogen adsorbed on a helium film. With plausible assumptions about experimental parameters this can explain (i) the 2 orders of magnitude discrepancy between previous theory and recent experiments and (ii) the anomalous dependence of the cold collision frequency shifts on the film's 3He covering. The mediated interaction is attractive, suggesting that in current experiments the gas will become unstable before reaching the Kosterlitz-Thouless transition.

[Cryopreserved human sperm deposits: usability after decades of storage]. / Kryokonservierte humane Spermadepots. Brauchbarkeit nach jahrzehntelanger Lagerung.

To determine the effect of long-term storage on cryopreserved human sperm, 238 individual samples from 34 cryopreserved sperm deposits that had been collected between 1976 and 1989 were evaluated at regular intervals. The material was from 34 patients, 18 of whom suffered from underlying malignant disease. Every 3 years a sample from each deposit was thawed for microscopic analysis. During the course of the storage period limited to a maximum of 21 years, all ejaculate parameters had deteriorated in comparison to fresh semen. Quantitative motility was the most sensitive parameter with a decrease of ca. 80%. Sperm density decreased hardly at all. The parameters of the criteria investigated did not decrease linearly or proportionally with the storage duration, but rather more directly after the freezing process or within the first 3 years. These changes became increasingly smaller as the storage time lengthened. Almost all of the deposits exhibited adequate quality at all times during storage. Consequently, 21-year permanent frozen storage in liquid nitrogen is safe regarding aspects of spermatology.

Complexity of small silicon self-interstitial defects.

The combination of long-time, tight-binding molecular dynamics and real-time multiresolution analysis techniques reveals the complexity of small silicon interstitial defects. The stability of identified structures is confirmed by ab initio relaxations. The majority of structures were previously unknown, demonstrating the effectiveness of the approach. A new, spatially extended tri-interstitial ground state structure is identified as a probable nucleation site for larger extended defects and may be key for the compact-to-extended transition.

Integrating new technology with managed care contracting.

The authors of this case study assisted eight teaching hospitals affiliated with the medical school of New Jersey in a financial analysis of the economic impact associated with utilization of the coronary artery stent implant. Consisting of a former health system CEO, a financial consultant/hospital trustee and an experienced hospital executive, this team shared their findings with medical and administrative staff to develop best practice models. The results of a new extended patient follow-up study contrasting outcomes and cost for stent vs. PTCA procedures will be reported later this year.