Stability and decay of Bloch oscillations in presence of time-dependent nonlinearity

We consider Bloch oscillations of Bose-Einstein condensates in presence of a time-modulated s-wave scattering length. Generically, interaction leads to dephasing and decay of the wave packet. Based on a cyclic-time argument, we find---additionally to the linear Bloch oscillation and a rigid soliton solution---an infinite family of modulations that lead to a periodic time evolution of the wave packet. In order to quantitatively describe the dynamics of Bloch oscillations in presence of time-modulated interactions, we employ two complementary methods: collective-coordinates and the linear stability analysis of an extended wave packet. We provide instructive examples and address the question of robustness against external perturbations.Comment: 15 pages, 8 figures. Slightly amended final versio

Dynamics and stability of Bose-Einstein solitons in tilted optical lattices

Bloch oscillations of Bose-Einstein condensates realize sensitive matter-wave interferometers. We investigate the dynamics and stability of bright-soliton wave packets in one-dimensional tilted optical lattices with a modulated mean-field interaction $g(t)$. By means of a time-reversal argument, we prove the stability of Bloch oscillations of breathing solitons that would be quasistatically unstable. Floquet theory shows that these breathing solitons can be more stable against certain experimental perturbations than rigid solitons or even non-interacting wave packets.Comment: final, published versio

Electron pairing in periodic potentials under an external electric field

We study the semiclassical dynamics of interacting electrons in a biased crystal lattice. A complex dynamical scenario emerges from the interplay between the Coulomb and the external electric fields. When the electrons are far apart, the Coulomb potential may be small compared to the external potential and the electrons oscillate with effective Bloch frequencies, determined by the local electric field. In the opposite case, nearby electrons either separate or form a bound pair, depending on the initial energy compared to the band width. The pair due to the Coulomb field is stable even in the absence of the external field.Comment: 5 pages, 4 figures, some minor corrections and some additional reference

Spin dynamics in helical molecules with nonlinear interactions

It is widely admitted that the helical conformation of certain chiral molecules may induce a sizable spin selectivity observed in experiments. Spin selectivity arises as a result of the interplay between a helicity-induced spin-orbit coupling (SOC) and electric dipole fields in the molecule. From the theoretical point of view, different phenomena might affect the spin dynamics in helical molecules, such as quantum dephasing, dissipation and the role of metallic contacts. With a few exceptions, previous studies usually neglect the local deformation of the molecule about the carrier, but this assumption seems unrealistic to describe charge transport in molecular systems. We introduce an effective model describing the electron spin dynamics in a deformable helical molecule with weak SOC. We find that the electron-lattice interaction allows the formation of stable solitons such as bright solitons with well defined spin projection onto the molecule axis. We present a thorough study of these bright solitons and analyze their possible impact on the spin dynamics in deformable helical molecules

How to Measure the Optical Quality of Focussing Solar Collectors without Laser Ray Tracing

Designers and Manufacturers need a tool for evaluating the optical quality of solar concentrators. This paper describes a novel alternative to the laser ray trace technique

Stable Bloch oscillations of cold atoms with time-dependent interaction

We investigate Bloch oscillations of interacting cold atoms in a mean-field framework. In general, atom-atom interaction causes dephasing and destroys Bloch oscillations. Here, we show that Bloch oscillations are persistent if the interaction is modulated harmonically with suitable frequency and phase. For other modulations, Bloch oscillations are rapidly damped. We explain this behavior in terms of collective coordinates whose Hamiltonian dynamics permits to predict a whole family of stable solutions. In order to describe also the unstable cases, we carry out a stability analysis for Bogoliubov excitations. Using Floquet theory, we are able to predict the unstable modes as well as their growth rate, found to be in excellent agreement with numerical simulations.Comment: minor changes; published versio

Burden of Migraine in Patients With Preventive Treatment Failure Attending European Headache Specialist Centers: Real-World Evidence From the BECOME Study

Migraña; Fracaso del tratamiento; Productividad laboralMigraine; Treatment failure; Work productivityMigranya; Fracàs del tractament; Productivitat laboralIntroduction Migraine is consistently ranked as one of the most disabling neurological conditions in the world, often causing a substantial impairment of daily activities and quality of life. It also carries a high economic burden of direct and indirect healthcare costs. Patients with difficult-to-treat migraine often cycle through different preventive therapies, but real-world prospective evidence describing the burden of migraine in patients with prior preventive treatment failure (PPTF) in Europe is limited. In BECOME, we aimed to characterize and assess the prevalence and burden of migraine in patients with PPTF attending specialist headache centers in Europe and Israel. Furthermore, we assessed this burden in pre-specified subgroups based on the frequency of monthly migraine days (MMD) and number of PPTFs. Methods BECOME was a prospective, non-interventional study conducted in two concurrent parts across 17 countries in Europe and Israel. In part 1, patients visiting the centers over a 3-month period were screened for frequency of PPTF, MMD, and other characteristics. In part 2, patients from part 1 with ≥ 1 PPTF and ≥ 4 MMD were enrolled, and impact of migraine on patient-reported outcomes, and healthcare resource utilization (HRU) were examined. Results In part 1 (n = 20,837), 62.2% of patients reported ≥ 1 PPTF. In part 2 (n = 2419), 15.3% of patients reported ≥ 4 PPTF. In part 2, the migraine burden measured by the EuroQoL 5 dimensions 5 level (EQ-5D-5L) questionnaire indicated an impact of at least moderate severity in performing usual activities in 26.5% of patients, pain/discomfort in 51.2%, and 26.1% reported being at least moderately anxious/depressed. Most patients reported a severe impact on daily activities and disability due to migraine. Abnormal Hospital Anxiety and Depression subscale scores of ≥ 11 were observed in 29% (anxiety) and 19.8% (depression) of the population. In part 2, analysis of HRU showed 21.2% patients visited an emergency department and 8.4% were hospitalized for headache/migraine in the past year. Conclusions This study provides real-world evidence of the high personal, social, and HRU burden of migraine in Europe and Israel.This study was funded by Novartis Pharma AG, Basel, Switzerland. The study sponsor participated in the study design, data collection, data review, data analysis and writing of the report. The Rapid Service Fee was funded by Novartis Pharma AG, Basel, Switzerland