Random quantum channels I: graphical calculus and the Bell state phenomenon

This paper is the first of a series where we study quantum channels from the random matrix point of view. We develop a graphical tool that allows us to compute the expected moments of the output of a random quantum channel. As an application, we study variations of random matrix models introduced by Hayden \cite{hayden}, and show that their eigenvalues converge almost surely. In particular we obtain for some models sharp improvements on the value of the largest eigenvalue, and this is shown in a further work to have new applications to minimal output entropy inequalities.Comment: Several typos were correcte

Generating random density matrices

We study various methods to generate ensembles of random density matrices of a fixed size N, obtained by partial trace of pure states on composite systems. Structured ensembles of random pure states, invariant with respect to local unitary transformations are introduced. To analyze statistical properties of quantum entanglement in bi-partite systems we analyze the distribution of Schmidt coefficients of random pure states. Such a distribution is derived in the case of a superposition of k random maximally entangled states. For another ensemble, obtained by performing selective measurements in a maximally entangled basis on a multi--partite system, we show that this distribution is given by the Fuss-Catalan law and find the average entanglement entropy. A more general class of structured ensembles proposed, containing also the case of Bures, forms an extension of the standard ensemble of structureless random pure states, described asymptotically, as N \to \infty, by the Marchenko-Pastur distribution.Comment: 13 pages in latex with 8 figures include

A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations

We present constraints on the number of Galactic magnetars, which we have established by searching for sources with periodic variability in 506 archival Chandra observations and 441 archival XMM-Newton observations of the Galactic plane (|b|<5 degree). Our search revealed four sources with periodic variability on time scales of 200-5000 s, all of which are probably accreting white dwarfs. We identify 7 of 12 known Galactic magnetars, but find no new examples with periods between 5 and 20 s. We convert this non-detection into limits on the total number of Galactic magnetars by computing the fraction of the young Galactic stellar population that was included in our survey. We find that easily-detectable magnetars, modeled after persistent anomalous X-ray pulsars, could have been identified in 5% of the Galactic spiral arms by mass. If we assume there are 3 previously-known examples within our random survey, then there are 59 (+92,-32) in the Galaxy. Transient magnetars in quiescence could have been identified throughout 0.4% of the spiral arms, and the lack of new examples implies that <540 exist in the Galaxy (90% confidence). Similar constraints are found by considering the detectability of transient magnetars in outburst by current and past X-ray missions. For assumed lifetimes of 1e4 yr, we find that the birth rate of magnetars could range between 0.003 and 0.06 per year. Therefore, the birth rate of magnetars is at least 10% of that for normal radio pulsars. The magnetar birth rate could exceed that of radio pulsars, unless the lifetimes of transient magnetars are >1e5 yr. Obtaining better constraints will require wide-field X-ray or radio searches for transient X-ray pulsars similar to XTE J1810--197, AX J1845.0--0250, CXOU J164710.2--455216, and 1E 1547.0-5408.Comment: 16 pages, 10 figures, one with a bit of color. submitted to Ap

Assessment of the technological performance of some Saccharomyces and non-Saccharomyces indigenous yeast strains

The study aimed to assess the technological potential of four indigenous Saccharomyces cerevisiae strains (S. cer. 4.1.11, S. cer. 4.3, S. cer. 4.6 and S. cer. 4.10), as possible sources for starter cultures. The experiments were carried out at micropilot level on the natural must of 'Fetească albă' cultivar. The evaluation of the yeasts was carried out according to the chemical parameters and volatile compounds analysed in the obtained wines compared to the wine obtained with a commercial starter culture (CSC). The values of the main physico-chemical parameters analyzed in the obtained wines were similar to those determined in the control wine. The average values of the volatile compounds with positive impact on the wine aroma ranged within the interval 177.46 - 217.81 mg/L, a higher value compared to the control wine, respectively 166.33 mg/L. The use of the indigenous strain Torulospora delbrueckii (T.d 10) in association with the strains S. cer. 4.1.11 or S. cer. 4.10 led to an increase of 12.56%, respectively 8.30% in glycerol concentrations, as well as an increase of 11.94% to 14.49% in the average concentration of volatile compounds. Harnessing the oenological potential of the yeasts tested in sequential fermentations proved dependent on the time allowed for the development of the strain T.d 10, namely 24 and 48 hours, as well as on the yeasts used. Thus, in the wines obtained by the association T.d 10/ S. cer. 4.10, in which the development of the culture T.d 10 was carried out for 48 hours, we noticed an increase of 12.52% and, respectively 32.95%, in the average of volatile compounds, compared to the monoculture wine for the same S. cer. 4.10 strain and to the control wine (CSC)

Random graph states, maximal flow and Fuss-Catalan distributions

For any graph consisting of $k$ vertices and $m$ edges we construct an ensemble of random pure quantum states which describe a system composed of $2m$ subsystems. Each edge of the graph represents a bi-partite, maximally entangled state. Each vertex represents a random unitary matrix generated according to the Haar measure, which describes the coupling between subsystems. Dividing all subsystems into two parts, one may study entanglement with respect to this partition. A general technique to derive an expression for the average entanglement entropy of random pure states associated to a given graph is presented. Our technique relies on Weingarten calculus and flow problems. We analyze statistical properties of spectra of such random density matrices and show for which cases they are described by the free Poissonian (Marchenko-Pastur) distribution. We derive a discrete family of generalized, Fuss-Catalan distributions and explicitly construct graphs which lead to ensembles of random states characterized by these novel distributions of eigenvalues.Comment: 37 pages, 24 figure

Valorizing intangible cultural heritage through community-based tourism in Lăpuș Land, Transylvania

Community-based tourism has been promoted as a means of development whereby the social, environmental and economic needs of local communities are met through the offering of a tourism product. Local culture may be a community’s most valuable asset for tourism if planned and managed properly. Its intangible cultural heritage may provide a community with a competitive advantage and uniqueness, one that differentiates it from all other communities. However, with increasing commodification of tourism, many smaller rural communities face several challenges in developing community-based tourism. The present paper explores the concept of community-based tourism, as a basis for the valorization of intangible cultural heritage, with a special focus on a regional tourist destination in Romania. Aiming to identify tourists’ experience, a research was conducted among Japanese visitors who discovered the intangible cultural heritage of the studied area during an academic summer camp

Random matrix techniques in quantum information theory

The purpose of this review article is to present some of the latest developments using random techniques, and in particular, random matrix techniques in quantum information theory. Our review is a blend of a rather exhaustive review, combined with more detailed examples -- coming from research projects in which the authors were involved. We focus on two main topics, random quantum states and random quantum channels. We present results related to entropic quantities, entanglement of typical states, entanglement thresholds, the output set of quantum channels, and violations of the minimum output entropy of random channels

Radical heminephrectomy for left sided upper pole renal tumor on horseshoe kidney – case report and review of the literature

Ion Chiricuţă Oncological Institute Cluj Napoca, Al V-lea Congres de Urologie, Dializă şi Transplant Renal din Republica Moldova cu participare internaţională (1-13 iunie 2011)Abstract Tumoral pathology of the horseshoe kidney is a rare pathology, only half of the tumors represent renal cell carcinoma. We will present the case of a 45 year old man known with horseshoe kidney diagnosed with a large renal tumor on the left side. CT angiography was performed preoperatively to asses the vascular anomalies of the renal pedicle and it was used for planning the surgical approach. The approach was transperitoneal by subcostal incision with lateral paramedian extension

Random repeated quantum interactions and random invariant states

We consider a generalized model of repeated quantum interactions, where a system $\mathcal{H}$ is interacting in a random way with a sequence of independent quantum systems $\mathcal{K}_n, n \geq 1$. Two types of randomness are studied in detail. One is provided by considering Haar-distributed unitaries to describe each interaction between $\mathcal{H}$ and $\mathcal{K}_n$. The other involves random quantum states describing each copy $\mathcal{K}_n$. In the limit of a large number of interactions, we present convergence results for the asymptotic state of $\mathcal{H}$. This is achieved by studying spectral properties of (random) quantum channels which guarantee the existence of unique invariant states. Finally this allows to introduce a new physically motivated ensemble of random density matrices called the \emph{asymptotic induced ensemble}

Dry Bacterial Cellulose and Carboxymethyl Cellulose formulations with interfacial-active performance: processing conditions and redispersion

Dry or powdered formulations of food additives facilitate transportation, storage, preservation and handling. In this work, dry formulations of bacterial cellulose and carboxymethyl cellulose (BC:CMC), easily redispersible and preserving the functionality of the never-dried dispersions are reported. Different processing parameters and their effect on the materials properties were evaluated, namely: (i) wet-grinding of BC (Hand-blender, Microcut Head Impeller, High-pressure Homogenizer), (ii) drying of BC:CMC mixtures (fast drying at130 °C and slow drying at 80 °C) and subsequent (iii) comminution to different particle sizes. The dispersibility of the obtained BC:CMC powders was evaluated, and their functionality after redispersion was assessed by measuring the dynamic viscosity, the effect in oil/water interfacial tension (liquidliquid system) and the stabilization of cocoa in milk (solidliquid system). The size of BC fibre bundles was of paramount relevance to its stabilizing ability in multiphasic systems. A more extensive wet-grinding of the BC fibres was accompanied by a loss in the BC:CMC functionality, related to the increasingly smaller size of the BC bundles. Indeed, as the Dv (50) of the wet BC bundles was reduced from 1228 to 55 µm, the BC:CMC viscosity profile dropped and the effect on interfacial tension decreased. This effect was observed both on the never-dried and dry BC:CMC formulations. On the other hand, the drying method did not play a major effect in the materials properties. In a benchmarking study, the BC:CMC formulations, at a low concentration (0.15%), had better stabilizing ability of the cocoa particles than several commercial cellulose products.Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10570-020-03211-9) contains supplementary material, which is available to authorized users.This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by the European Regional Development Fund under the scope of Norte2020-Programa Operacional Regional do Norte. Daniela Martins also gratefully acknowledges FCT for the PhD scholarship, reference SFRH/BD/115917/2016.info:eu-repo/semantics/publishedVersio