Dipolar Bose-Einstein condensate of Stationary-Light Dark-state Polaritons

We put forward and discuss in detail a scheme to achieve Bose-Einstein condensation of stationary-light dark-state polaritons with dipolar interaction. To this end we have introduced a diamond-like coupling scheme in a vapor of Rydberg atoms under the frozen gas approximation. To determine the system's dynamics we employ normal modes and identify the dark-state polariton corresponding to one of the modes. We show that in contrast to atomic dipolar ultra-cold vapors dark-state polariton Bose-Einstein condensates proposed here can be stable for a negative dipolar interaction constant.Comment: 5 pages, 1 figur

Enhanced electron correlations in FeSb2_2

FeSb$_2$ has been recently identified as a new model system for studying many-body renormalizations in a $d$-electron based narrow gap semiconducting system, strongly resembling FeSi. The electron-electron correlations in FeSb$_2$ manifest themselves in a wide variety of physical properties including electrical and thermal transport, optical conductivity, magnetic susceptibility, specific heat and so on. We review some of the properties that form a set of experimental evidences revealing the crucial role of correlation effects in FeSb$_2$. The metallic state derived from slight Te doping in FeSb$_2$, which has large quasiparticle mass, will also be introduced.Comment: 9 pages, 7 figures; submitted to Annalen der Physi

The madrigal.

The madrigal is the oldest of concerted secular forms. It had its origin in northern Italy, perhaps as early as the twelfth century. The early compositions had none of the elaborate devices which characterize the madrigals of the sixteenth century. Francesco di Landino, (1325-1390), an Italian, and the leading musician of the Florentine school of his time, wrote a madrigal, Tu che l\u27opera d\u27altrul, an extract of which appears in Fellowes\u27 English Madrigal (1) Composers. Landino\u27s life is interesting. He was blind from youth, but was organist for many years in the church of San Lorenzo in Florence. His madrigal was different from those of the sixteenth century in that it was written for two voices only, and single syllables of words were often used over several bars of music in the same manner as the church music of that early period. Each voice, in his composition, followed the other with frequent points of imitation, a characteristic which remained essential in the development of the madrigal

Highly Dispersive Electron Relaxation and Colossal Thermoelectricity in the Correlated Semiconductor FeSb2_2

We show that the colossal thermoelectric power, $S(T)$, observed in the correlated semiconductor FeSb$_2$ below 30\,K is accompanied by a huge Nernst coefficient $\nu(T)$ and magnetoresistance MR$(T)$. Markedly, the latter two quantities are enhanced in a strikingly similar manner. While in the same temperature range, $S(T)$ of the reference compound FeAs$_2$, which has a seven-times larger energy gap, amounts to nearly half of that of FeSb$_2$, its $\nu(T)$ and MR$(T)$ are intrinsically different to FeSb$_2$: they are smaller by two orders of magnitude and have no common features. With the charge transport of FeAs$_2$ successfully captured by the density functional theory, we emphasize a significantly dispersive electron-relaxation time $\tau(\epsilon_k)$ due to electron-electron correlations to be at the heart of the peculiar thermoelectricity and magnetoresistance of FeSb$_2$.Comment: 8 pages, 5 figure

Fabrication of wide-IF 200–300 GHz superconductor–insulator–superconductor mixers with suspended metal beam leads formed on silicon-on-insulator

We report on a fabrication process that uses SOI substrates and micromachining techniques to form wide-IF SIS mixer devices that have suspended metal beam leads for rf grounding. The mixers are formed on thin 25 µm membranes of Si, and are designed to operate in the 200–300 GHz band. Potential applications are in tropospheric chemistry, where increased sensitivity detectors and wide-IF bandwidth receivers are desired. They will also be useful in astrophysics to monitor absorption lines for CO at 230 GHz to study distant, highly redshifted galaxies by reducing scan times. Aside from a description of the fabrication process, electrical measurements of these Nb/Al–AlNx/Nb trilayer devices will also be presented. Since device quality is sensitive to thermal excursions, the new beam lead process appears to be compatible with conventional SIS device fabrication technology

Gaussian inference for data-driven state-feedback design of nonlinear systems

Data-driven control of nonlinear systems with rigorous guarantees is a challenging problem as it usually calls for nonconvex optimization and requires often knowledge of the true basis functions of the system dynamics. To tackle these drawbacks, this work is based on a data-driven polynomial representation of general nonlinear systems exploiting Taylor polynomials. Thereby, we design state-feedback laws that render a known equilibrium point globally asymptotically stable while operating with respect to a desired quadratic performance criterion. The calculation of the polynomial state feedback boils down to a single sum-ofsquares optimization problem, and hence to computationally tractable linear matrix inequalities. Moreover, we examine state-input data in presence of Gaussian noise by Bayesian inference to overcome the conservatism of deterministic noise characterizations from recent data-driven control approaches for Gaussian noise.Comment: Final version, accepted for presentation at the 22nd IFAC World Congress, 202

Mechanical Complication with Broviac Repair Kit in a 4-Year-Old Boy with MEN 2a

Background. Mechanical complications in the use of indwelling central venous catheters (CVCs) such as the Broviac catheter (BC) include kinking, occlusion, dislocation or leaking. We report on a mechanical complication after using a repair kit for the BC. Method. A 4-year old boy, suffering from multiple endocrine neoplasia type 2a (MEN 2a), intestinal aganglionosis (Hirschsprung's disease), and short bowel syndrome, required a BC for home parenteral nutrition. Result. Due to recurrent leakage of the BC, 5 subsequent repairs were necessary within seven months. During one repair a metallic tube belonging to the repair kit was found to have migrated proximally to the skin entrance level within the BC and requiring surgical removal. Conclusion. To our knowledge, this is the first report focusing on such a serious complication using a BC and its repair kit. The proximal migration of this metallic tube constitutes a distinct theoretical risk of endothoracic foreign body embolization

Detection of gravitational-wave signals from binary neutron star mergers using machine learning

As two neutron stars merge, they emit gravitational waves that can potentially be detected by Earth-bound detectors. Matched-filtering-based algorithms have traditionally been used to extract quiet signals embedded in noise. We introduce a novel neural-network-based machine learning algorithm that uses time series strain data from gravitational-wave detectors to detect signals from nonspinning binary neutron star mergers. For the Advanced LIGO design sensitivity, our network has an average sensitive distance of 130 Mpc at a false-alarm rate of ten per month. Compared to other state-of-the-art machine learning algorithms, we find an improvement by a factor of 4 in sensitivity to signals with a signal-to-noise ratio between 8 and 15. However, this approach is not yet competitive with traditional matched-filtering-based methods. A conservative estimate indicates that our algorithm introduces on average 10.2 s of latency between signal arrival and generating an alert. We give an exact description of our testing procedure, which can be applied not only to machine-learning-based algorithms but all other search algorithms as well. We thereby improve the ability to compare machine learning and classical searches. © 2020 authors. Published by the American Physical Society