Entanglement and spin squeezing in non-Hermitian phase transitions

We show that non-Hermitian dynamics generate substantial entanglement in many-body systems. We consider the non-Hermitian Lipkin-Meshkov-Glick model and show that its phase transition occurs with maximum multiparticle entanglement: there is full N-particle entanglement at the transition, in contrast to the Hermitian case. The non-Hermitian model also exhibits more spin squeezing than the Hermitian model, showing that non-Hermitian dynamics are useful for quantum metrology. Experimental implementations with trapped ions and cavity QED are discussed.Comment: 5 pages + appendi

Photon Scattering from a System of Multi-Level Quantum Emitters. I. Formalism

We introduce a formalism to solve the problem of photon scattering from a system of multi-level quantum emitters. Our approach provides a direct solution of the scattering dynamics. As such the formalism gives the scattered fields amplitudes in the limit of a weak incident intensity. Our formalism is equipped to treat both multi-emitter and multi-level emitter systems, and is applicable to a plethora of photon scattering problems including conditional state preparation by photo-detection. In this paper, we develop the general formalism for an arbitrary geometry. In the following paper (part II), we reduce the general photon scattering formalism to a form that is applicable to $1$-dimensional waveguides, and show its applicability by considering explicit examples with various emitter configurations.Comment: This is first part of a two part series of papers. It has 11 pages, double column, and one figur

Towards new insights in the phylogeny of the Spermacoce clade: an integrative taxonomic approach using morphology, anatomy, ecology and phylogenetics reveáis the new genus Leonoria

Phylogenetic inference analyses o f two nuclear and four plastid DNA markers from 82 accessions representing 19 genera o f the Spermacoce clade (Spermacoceae-Rubiaceae) confirm that the Brazilian genus Denscantia is biphyletic. By the analyses o f reproductive morphological characters, foliar morpho-anatomy and histochemical, geographical distribution ranges, and ecological niche derived from climatic space, Denscantia caldcóla is shown as a distinct lineage from the other Denscantia species, indicating its taxonomic segregation into a new monospecific genus Leonoria. Significant morphological diíferences o f Leonoria with Denscantia were found in inflorescence organization, stigma shape, fruit dehiscence, and pollen morphology. Morphoanatomical variation among leaf traits were found in epidemial cells, occurrence o f trichomes, mesophyll histochemical, and vascular organization. Analysis o f occurrence records o f 205 specimens demonstrates a clear ecological distinction between o f Denscantia s.s. and Leonoria, which is ecologically confined to limestone outcrops associated with seasonally dry forests. The current study demonstrates the importance of an integrative taxonomic approach - in which múltiple disciplines are combined - to the unravel complex taxonomic pattems within Rubiaceae. The genus Leonoria, to be newly described, is dedicated to Professor Elsa Leonor Cabral

Smarandache type functions obtained by duality

we extend the Smarandache function from the set N* of positive integers to the set Q of rational

Brorfelde Schmidt CCD Catalog (BSCC)

The Brorfelde Schmidt CCD Catalog (BSCC) contains about 13.7 million stars, north of +49 deg Declination with precise positions and V, R photometry. The catalog has been constructed from the reductions of 18,667 CCD frames observed with the Brorfelde Schmidt Telescope between 2000 and 2007. The Tycho-2 catalog was used for astrometric and photometric reference stars. Errors of individual positions are about 20 to 200 mas for stars in the R = 10 to 18 mag range. External comparisons with 2MASS and SDSS reveal possible small systematic errors in the BSCC of up to about 30 mas. The catalog is supplemented with J, H, and K_s magnitudes from the 2MASS catalog. The catalog data file (about 550 MB ASCII, compressed) will be made available at the Strasbourg Data Center (CDS).Comment: 16 pages, 22 figures, 2 tables, accepted by A

A Large Brightness Enhancement of the QSO 0957+561 A Component

We report an increase of more than 0.2 mag in the optical brightness of the leading image (A) of the gravitational lens Q0957+561, detected during the 09/2000 -- 06/2001 monitoring campaign (2001 observing season). The brightening is similar to or even greater than the largest change ever detected during the 20 years of monitoring of this system. We discuss two different provisional explanations to this event: intrinsic source variability or microlensing (either short timescale microlensing or cessation of the historical microlensing). An exhaustive photometric monitoring of Q0957+561 is needed until summer of 2002 and during 2003 to discriminate between these possibilities.Comment: 13 pages including 3 figures and 1 table. Accepted for publication in ApJ Let

Data reduction for the AMBER instrument

We present here the general formalism and data processing steps used in the data reduction pipeline of the AMBER instrument. AMBER is a three-telescope interferometric beam combiner in J, H and K bands installed at ESO\'s Very Large Telescope Interferometer. The fringes obtained on the 3 pairs of telescopes are spatially coded and spectrally dispersed. These are monitored on a 512x512 infrared camera at frame rates up to 100 frames per second, and this paper presents the algorithm used to retrieve the complex coherent visibility of the science target and the subsequent squared visibility, dierential phase and phase closure on the 3 bases and in the 3 spectral bands available in AMBER

Does the current taxonomic delimitation of Galianthe find support in phylogenetic perspective?

Galianthe Griseb. is a neotropical genus comprising 50 species divided into two subgenera: G. subgen. Galianthe (41 spp.), characterized by homogeneous morphological traits, with species further divided into two sections (G. secc. Galianthe and G. secc. Laxae); and G. subgen. Ebelia (14 spp.) with more heterogeneous morphological characteristics. Due to its morphological similarity with other genera, Galianthe has historically been associated with Borreria, Spermacoce, Diodia (based on fruit type), as well as Denscantia and Emmeorhiza (based on inflorescence type). In recent years, molecular studies have established Galianthe as a basal genus within the Spermacoce clade, closely related to other genera such as Carajasia and Schwendenera. Despite the progress made in recent molecular studies, the studies have focused on a limited number of species within the genus, failing to encompass all infrageneric categories. Questioning of the current taxonomic delimitation of the genus, this study aims to test the monophyly of Galianthe and explore its infrageneric and interspecific phylogenetic relationships. Three markers (two nuclear: ITS, ETS, and one plastid: rps16) were utilized, encompassing 107 entities, including 42 Galianthe species, thereby representing 76% of the current genus diversity, as well as 17 closely related genera within the Spermacoce clade. The phylogenetic results confirm the monophyly of Galianthe, revealing the presence of three major subclades. Subclades I and II comprise several G. subgen. Ebelia species, whereas subclade III consists of all G. subgen. Galianthe species plus G. angulata. Regarding the sections, monophyly was not supported. Based on these findings, it can be concluded that G. subgen. Ebelia is paraphyletic, G. subgen. Galianthe is potentially paraphyletic due to G. angulata, and there is no clear distinction between the sections

A Robust Determination of the Time Delay in 0957+561A,B and a Measurement of the Global Value of Hubble's Constant

Photometric monitoring of the gravitational lens system 0957+561A,B in the g and r bands with the Apache Point Observatory (APO) 3.5 m telescope during 1996 shows a sharp g band event in the trailing (B) image light curve at the precise time predicted from the observation of an event during 1995 in the leading (A) image with a delay of 415 days. This success confirms the "short delay," and the lack of any feature at a delay near 540 days rejects the "long delay" for this system, resolving a long-standing controversy. A series of statistical analyses of our light curve data yield a best fit delay of 417 +/- 3 days (95% confidence interval). Recent improvements in the modeling of the lens system (consisting of a galaxy and cluster) allow us to derive a value of the global (at z = 0.36) value of Hubble's constant H_0 using Refsdal's method, a simple and direct distance determination based on securely understood physics and geometry. The result is H_0 = 63 +/- 12 km/s/Mpc (for Omega = 1) where this 95% confidence interval is dominated by remaining lens model uncertainties.Comment: accepted by ApJ, AASTeX 4.0 preprint, 4 PostScript figure