Correlated motion of two atoms trapped in a single mode cavity field

We study the motion of two atoms trapped at distant positions in the field of a driven standing wave high-Q optical resonator. Even without any direct atom-atom interaction the atoms are coupled through their position dependent influence on the intracavity field. For sufficiently good trapping and low cavity losses the atomic motion becomes significantly correlated and the two particles oscillate in their wells preferentially with a 90 degrees relative phase shift. The onset of correlations seriously limits cavity cooling efficiency, raising the achievable temperature to the Doppler limit. The physical origin of the correlation can be traced back to a cavity mediated cross-friction, i.e. a friction force on one particle depending on the velocity of the second particle. Choosing appropriate operating conditions allows for engineering these long range correlations. In addition this cross-friction effect can provide a basis for sympathetic cooling of distant trapped clouds.Comment: 10 pages, 9 figures, accepted for publication in Phys. Rev. A. Minor grammatical changes to previous versio

Eigenvector Approximation Leading to Exponential Speedup of Quantum Eigenvalue Calculation

We present an efficient method for preparing the initial state required by the eigenvalue approximation quantum algorithm of Abrams and Lloyd. Our method can be applied when solving continuous Hermitian eigenproblems, e.g., the Schroedinger equation, on a discrete grid. We start with a classically obtained eigenvector for a problem discretized on a coarse grid, and we efficiently construct, quantum mechanically, an approximation of the same eigenvector on a fine grid. We use this approximation as the initial state for the eigenvalue estimation algorithm, and show the relationship between its success probability and the size of the coarse grid.Comment: 4 page

Nonequilibrium Phase Diagram of a Driven-Dissipative Many-Body System

We study the nonequilibrium dynamics of a many-body bosonic system on a lattice, subject to driving and dissipation. The time-evolution is described by a master equation, which we treat within a generalized Gutzwiller mean field approximation for density matrices. The dissipative processes are engineered such that the system, in the absence of interaction between the bosons, is driven into a homogeneous steady state with off-diagonal long range order. We investigate how the coherent interaction affects qualitatively the properties of the steady state of the system and derive a nonequilibrium phase diagram featuring a phase transition into a steady state without long range order. The phase diagram exhibits also an extended domain where an instability of the homogeneous steady state gives rise to a persistent density pattern with spontaneously broken translational symmetry. In the limit of small particle density, we provide a precise analytical description of the time-evolution during the instability. Moreover, we investigate the transient following a quantum quench of the dissipative processes and we elucidate the prominent role played by collective topological variables in this regime.Comment: 23 pages, 15 figure

A randomized controlled trial of liposomal cyclosporine A for inhalation in the prevention of bronchiolitis obliterans syndrome following lung transplantation

Bronchiolitis obliterans; Clinical research; Lung transplantationBronquiolitis obliterante; Investigación clínica; Trasplante de pulmónBronquiolitis obliterant; Recerca clínica; Trasplantament de pulmóLong-term survival after lung transplantation is limited by chronic allograft dysfunction. The aim of this study was to investigate the effect of locally augmented immunosuppression with liposomal cyclosporine A for inhalation (L-CsA-i) for the prevention of bronchiolitis obliterans syndrome (BOS). In a randomized, double-blind, placebo-controlled, multi-center Phase 3 study, 180 LT recipients in BOS grade 0 were planned to receive L-CsA-i or placebo in addition to triple-drug immunosuppression. L-CsA-i was administered twice daily via an Investigational eFlow nebulizer to recipients of single (SLT) and bilateral lung transplants (BLT) within 6–32 weeks posttransplant, and continued for 2 years. The primary endpoint was BOS-free survival. 130 patients were enrolled before the study was prematurely terminated for business reasons. Despite a 2-year actuarial difference in BOS-free survival of 14.1% in favor of L-CsA-i in the overall study population, the primary endpoint was not met (p = .243). The pre-defined per protocol analysis of SLT recipients (n = 24) resulted in a treatment difference of 58.2% (p = .053). No difference was observed in the BLT (n = 48) subpopulation (p = .973). L-CsA-i inhalation was well tolerated. Although this study failed to meet its primary endpoint, the results warrant additional investigation of L-CsA-i in lung transplant recipients.The study was funded by PARI Pharma GmbH. Open access funding enabled and organized by ProjektDEAL

Impact of Lung Function Decline on Mortality in Lung Transplant Recipients: Long-Term Results From the L-CsA-i Study for the Prevention of Bronchiolitis Obliterans Syndrome

Cyclosporine (CsA); Chronic rejection; Lung transplantationCiclosporina (CsA); Rechazo crónico; Trasplante de pulmónCiclosporina (CsA); Rebuig crònic; Trasplantament de pulmóBackground: Chronic lung allograft dysfunction (CLAD) is defined by a progressive loss of FEV1 and is associated with premature mortality. The aim of this study was to investigate the direct association between FEV1 decline and risk of mortality in patients after lung transplantation (LTx). Methods: 10-year follow up data from lung transplant recipients participating in randomized placebo-controlled clinical trial investigating the role of liposomal Cyclosporine A for inhalation (L-CsA-i) in the prevention of bronchiolitis obliterans syndrome (NCT01334892) was used. The association between the course of FEV1 over time and the risk of mortality was assessed using joint modeling and Cox regression analysis. Results: A total of 130 patients were included. Predictors of FEV1 decline were a higher absolute FEV1 at baseline and male sex. The joint model analysis indicated a significant association of change of FEV1 and risk of mortality (p < 0.001), with a predicted 3.4% increase in mortality risk for each 1% decline in FEV1. Significant predictors of a progressive phenotype were single LTx and treatment with placebo (as opposed to L-CsA-i). At the end of follow-up, 82 patients (63.1%) were still alive. Cox regression analyses for mortality identified only single LTx as a predictor of higher risk. Conclusion: Based on our observation of a close association between FEV1 and mortality over a period of 10 years we suggest FEV1 as a valid predictor of mortality and a suitable surrogate endpoint in the investigation of early interventions.This study was funded by Zambon S.p.A., Milan, Italy

Single atom quantum walk with 1D optical superlattices

A proposal for the implementation of quantum walks using cold atom technology is presented. It consists of one atom trapped in time varying optical superlattices. The required elements are presented in detail including the preparation procedure, the manipulation required for the quantum walk evolution and the final measurement. These procedures can be, in principle, implemented with present technology.Comment: 6 pages, 7 figure

Imunosupresivno liječenje nakon transplantacije pluća

Lung transplantation has become a life-saving procedure for individuals with variety of end-stage respiratory diseases. Optimal immunosuppression remains the key to long-term graft survivival. The protocols for immunosuppressive therapy following lung transplantation can be divided into three general categories: induction, maintenance, and treatment of rejection. The goal of induction therapy is to provide intense immunosuppression in the early post-transplantation period, when the risk of allograft rejection is the highest. Induction agents primarily target T lymphocytes, which are considered the effector cells in cell-mediated rejection. Current maintenance therapy typically includes a calcineurin inhibitor, nucleotide blocking agent and corticosteroid. Pulse steroids are generally the first treatment of acute cellular rejection. Therapeutic modalities for treatment of refractory cellular rejection include switch from cyclosporine to tacrolimus, use of lymphocyte depleting agents, azithromycine, and extracorporeal photopheresis. Treatment options for humoral rejections include plasmapheresis and immunoglobulines in combination with rituximab.Transplantacija pluća je postupak koji spašava život bolesnicima s krajnjim stadijem različitih plućnih bolesti. Optimalna imunosupresija predstavlja ključ dugotrajnog preživljenja presadka. Protokoli imunosupresivnog liječenja nakon transplantacije pluća mogu se podijeliti u tri glavne grupe: indukcijska terapija, terapija održavanja i terapija liječenja reakcija odbacivanja. Cilj indukcijske terapije je osigurati intenzivnu imunosupresiju u ranom posttransplantacijskom periodu, kada je rizik odbacivanja alografta najveći. Indukcijski lijekovi su primarno usmjereni na T limfocite, koji se smatraju glavnim stanicama u stanično posredovanoj reakciji odbacivanja. Trenutno se terapija održavanja tipično sastoji od inhibitora kalcineurina, antimetabolita i kortikosteroida. Pulsne doze kortikosteroida su prvi izbor liječenja akutnog staničnog odbacivanja. Načini liječenja refraktornog staničnog odbacivanja uključuju zamjenu ciklosporina takrolimusom, primjenu monoklonalnih i poliklonalnih antilimfocitnih protutijela, azitromicina i ekstrakorporalne fotofereze. Mogućnosti liječenja humoralnog odbacivanja uključuju plazmaferezu i imunoglobuline u kombinaciji s rituksimabom

Convergence rate of dimension reduction in Bose-Einstein condensates

In this paper, we study dimension reduction of the three-dimensional (3D) Gross-Pitaevskii equation (GPE) modelling Bose-Einstein condensation under different limiting interaction and trapping frequencies parameter regimes. Convergence rates for the dimension reduction of 3D ground state and dynamics of the GPE in the case of disk-shaped condensation and cigar-shaped condensation are reported based on our asymptotic and numerical results. In addition, the parameter regimes in which the 3D GPE cannot be reduced to lower dimensions are identified.Comment: 27pages; 9 figure

Light propagation in atomic Mott Insulators

We study radiation-matter interaction in a system of ultracold atoms trapped in an optical lattice in a Mott insulator phase. We develop a fully general quantum model, and we perform calculations for a one-dimensional geometry at normal incidence. Both two- and three-level $\Lambda$ atomic configurations are studied. The polariton dispersion and the reflectivity spectra are characterized in the different regimes, for both semi-infinite and finite-size geometries. We apply this model to propose a photon energy lifter experiment: a device which is able to shift the carrier frequency of a slowly travelling wavepacket without affecting the pulse shape nor its coherence

Monte Carlo techniques for real-time quantum dynamics

The stochastic-gauge representation is a method of mapping the equation of motion for the quantum mechanical density operator onto a set of equivalent stochastic differential equations. One of the stochastic variables is termed the "weight", and its magnitude is related to the importance of the stochastic trajectory. We investigate the use of Monte Carlo algorithms to improve the sampling of the weighted trajectories and thus reduce sampling error in a simulation of quantum dynamics. The method can be applied to calculations in real time, as well as imaginary time for which Monte Carlo algorithms are more-commonly used. The method is applicable when the weight is guaranteed to be real, and we demonstrate how to ensure this is the case. Examples are given for the anharmonic oscillator, where large improvements over stochastic sampling are observed.Comment: 28 pages, submitted to J. Comp. Phy