Bright soliton to quantum droplet transition in a mixture of Bose-Einstein condensates

Attractive Bose-Einstein condensates can host two types of macroscopic self-bound states of different nature: bright solitons and quantum liquid droplets. Here, we investigate the connection between them with a Bose-Bose mixture confined in an optical waveguide. We develop a simple theoretical model to show that, depending on atom number and interaction strength, solitons and droplets can be smoothly connected or remain distinct states coexisting only in a bi-stable region. We experimentally measure their spin composition, extract their density for a broad range of parameters and map out the boundary of the region separating solitons from droplets.Comment: 9 pages, 6 figures, includes supplementary materia

Feshbach resonances in potassium Bose-Bose mixtures

We present a detailed study of the scattering properties of ultracold mixtures of bosonic potassium atoms. We locate 20 previously unobserved Feshbach resonances in isotopic 39K-41K mixtures. These are assigned to s-wave molecular channels by comparison to an asymptotic bound state model and coupled channels calculations. Additional Feshbach resonances are studied in spin mixtures of a single potassium isotope, both in 39K and 41K. In particular, we characterize the parameters of a selected 39K Feshbach resonance by radio-frequency association of Feshbach molecules. Our results could be exploited to refine the model potentials for potassium scattering. Furthermore, these new Feshbach resonances enlarge the range of experiments possible with degenerate Bose-Bose mixtures.Comment: 9 pages, 3 figures, 1 tabl

Observation of subdiffusion of a disordered interacting system

We study the transport dynamics of matter-waves in the presence of disorder and nonlinearity. An atomic Bose-Einstein condensate that is localized in a quasiperiodic lattice in the absence of atom-atom interaction shows instead a slow expansion with a subdiffusive behavior when a controlled repulsive interaction is added. The measured features of the subdiffusion are compared to numerical simulations and a heuristic model. The observations confirm the nature of subdiffusion as interaction-assisted hopping between localized states and highlight a role of the spatial correlation of the disorder.Comment: 8 pages, to be published on Physical Review Letter

Correlation function of weakly interacting bosons in a disordered lattice

One of the most important issues in disordered systems is the interplay of the disorder and repulsive interactions. Several recent experimental advances on this topic have been made with ultracold atoms, in particular the observation of Anderson localization, and the realization of the disordered Bose-Hubbard model. There are however still questions as to how to differentiate the complex insulating phases resulting from this interplay, and how to measure the size of the superfluid fragments that these phases entail. It has been suggested that the correlation function of such a system can give new insights, but so far little experimental investigation has been performed. Here, we show the first experimental analysis of the correlation function for a weakly interacting, bosonic system in a quasiperiodic lattice. We observe an increase in the correlation length as well as a change in shape of the correlation function in the delocalization crossover from Anderson glass to coherent, extended state. In between, the experiment indicates the formation of progressively larger coherent fragments, consistent with a fragmented BEC, or Bose glass.Comment: 16 pages, 8 figure

Quantum liquid droplets in a mixture of Bose-Einstein condensates

Bose-Einstein condensatesquantum mixturesquantum liquidsquantum fluctuationsQuantum droplets are small clusters of atoms self-bound by the balance of attractive and repulsive forces. Here we report on the observation of a novel type of droplets, solely stabilized by contact interactions in a mixture of two Bose-Einstein condensates. We demonstrate that they are several orders of magnitude more dilute than liquid helium by directly measuring their size and density via in situ imaging. Moreover, by comparison to a single-component condensate, we show that quantum many-body effects stabilize them against collapse. We observe that droplets require a minimum atom number to be stable. Below, quantum pressure drives a liquid-to-gas transition that we map out as a function of interaction strength. These ultra-dilute isotropic liquids remain weakly interacting and constitute an ideal platform to benchmark quantum many-body theories.Peer ReviewedPreprin

Relationships among classifications of ayurvedic medicine diagnostics for imbalances and western measures of psychological states: An exploratory study.

BackgroundAccording to Ayurveda, the traditional medical system of India, doshas are a combination of characteristics based on a five-element philosophy that drive our mental and physical tendencies. When the doshas, or functional principles, are out of balance in quality or quantity, wellbeing is adversely affected and symptoms manifest.ObjectiveThis study examined relationships among imbalances in the doshas (termed Vikruti) reported via questionnaire and Western measures of psychological states.Materials and methodsStudy participants were 101 women (n = 81) and men (n = 20), mean age 53.9 years (SD = 11.7; range 32-80). Participants completed questionnaires to categorize their Vikruti type and psychological states, which included depressed mood (CESD), anxiety (PROMIS), rumination & reflection (RRQ), mindfulness (MAAS), stress (PSS), and quality of life (Ryff).ResultsMultivariate general linear modeling, controlling for age, gender and body mass index (BMI), showed that Vata imbalance was associated with more anxiety (p ≤ 0.05), more rumination (p ≤ 0.01), less mindfulness (p ≤ 0.05), and lower overall quality of life (p ≤ 0.01). Pitta imbalance was associated with poorer mood (p ≤ 0.01) and less mindfulness (p ≤ 0.05), more anxiety (p ≤ 0.05) and stress (p ≤ 0.05). Kapha imbalance was associated with more stress (p ≤ 0.05), more rumination (p ≤ 0.05) and less reflection (p ≤ 0.05).ConclusionThese findings suggest that symptoms of mind-body imbalances in Ayurveda are differentially associated with western assessments of psychological states. Ayurvedic dosha assessment may be an effective way to assess physical as well as emotional wellbeing in research and clinical settings

Quantum diffusion with disorder, noise and interaction

Disorder, noise and interaction play a crucial role in the transport properties of real systems, but they are typically hard to control and study both theoretically and experimentally, especially in the quantum case. Here we explore a paradigmatic problem, the diffusion of a wavepacket, by employing ultra-cold atoms in a disordered lattice with controlled noise and tunable interaction. The presence of disorder leads to Anderson localization, while both interaction and noise tend to suppress localization and restore transport, although with completely different mechanisms. When only noise or interaction are present we observe a diffusion dynamics that can be explained by existing microscopic models. When noise and interaction are combined, we observe instead a complex anomalous diffusion. By combining experimental measurements with numerical simulations, we show that such anomalous behavior can be modeled with a generalized diffusion equation, in which the noise- and interaction-induced diffusions enter in an additive manner. Our study reveals also a more complex interplay between the two diffusion mechanisms in regimes of strong interaction or narrowband noise.Comment: 11 pages, 10 figure

BeppoSAX observations of 3C 273

We present preliminary results of BeppoSAX AO1 observations of 3C 273 performed in January 1997. We also present a close comparison with data obtained during the satellite SVP, in July 1996. On average, the AO1 flux is about a factor 2 higher than the flux detected during the SVP, and roughly on the middle of the historical X-ray flux range. Power law fits with galactic absorption to all observations yield spectral indices in the range 1.53-1.6, with the spectrum extending from 0.2 to at least up to 200 keV without any significant slope change. The broad band spectrum appears basically featureless, marking a clear difference from the SVP data, where an absorption feature at low energy and a fluorescence iron emission line are present. The lack of cold/warm matter signatures in our data may indicate that, at this "high" level of luminosity, the featureless continuum produced in a relativistic jet overwhelms any thermal and/or reprocessing component, while the two components were at least comparable during the "low" state of July 1996.Comment: 1+4 pages, 3 ps inlined figures, espcrc2.sty. Proc. of the Conf. "The Active X-Ray Sky: Results from BeppoSAX and Rossi-XTE", Rome 21-24 October 199

A γ-secretase inhibitor, but not a γ-secretase modulator, induced defects in BDNF axonal trafficking and signaling: evidence for a role for APP.

Clues to Alzheimer disease (AD) pathogenesis come from a variety of different sources including studies of clinical and neuropathological features, biomarkers, genomics and animal and cellular models. An important role for amyloid precursor protein (APP) and its processing has emerged and considerable interest has been directed at the hypothesis that Aβ peptides induce changes central to pathogenesis. Accordingly, molecules that reduce the levels of Aβ peptides have been discovered such as γ-secretase inhibitors (GSIs) and modulators (GSMs). GSIs and GSMs reduce Aβ levels through very different mechanisms. However, GSIs, but not GSMs, markedly increase the levels of APP CTFs that are increasingly viewed as disrupting neuronal function. Here, we evaluated the effects of GSIs and GSMs on a number of neuronal phenotypes possibly relevant to their use in treatment of AD. We report that GSI disrupted retrograde axonal trafficking of brain-derived neurotrophic factor (BDNF), suppressed BDNF-induced downstream signaling pathways and induced changes in the distribution within neuronal processes of mitochondria and synaptic vesicles. In contrast, treatment with a novel class of GSMs had no significant effect on these measures. Since knockdown of APP by specific siRNA prevented GSI-induced changes in BDNF axonal trafficking and signaling, we concluded that GSI effects on APP processing were responsible, at least in part, for BDNF trafficking and signaling deficits. Our findings argue that with respect to anti-amyloid treatments, even an APP-specific GSI may have deleterious effects and GSMs may serve as a better alternative