Complete elimination of information leakage in continuous-variable quantum communication channels

In all lossy communication channels realized to date, information is inevitably leaked to a potential eavesdropper. Here we present a communication protocol that does not allow for any information leakage to a potential eavesdropper in a purely lossy channel. By encoding information into a restricted Gaussian alphabet of squeezed states we show, both theoretically and experimentally, that the Holevo information between the eavesdropper and the intended recipient can be exactly zero in a purely lossy channel while minimized in a noisy channel. This result is of fundamental interest, but might also have practical implications in extending the distance of secure quantum key distribution.Comment: 9 pages, 5 figure

Experimental Investigation of the Evolution of Gaussian Quantum Discord in an Open System

Gaussian quantum discord is a measure of quantum correlations in Gaussian systems. Using Gaussian discord we quantify the quantum correlations of a bipartite entangled state and a separable two-mode mixture of coherent states. We experimentally analyze the effect of noise addition and dissipation on Gaussian discord and show that the former noise degrades the discord while the latter noise for some states leads to an increase of the discord. In particular, we experimentally demonstrate the near-death of discord by noisy evolution and its revival through dissipation.Comment: 5 pages, 5 figure

Towards Error Handling in a DSL for Robot Assembly Tasks

This work-in-progress paper presents our work with a domain specific language (DSL) for tackling the issue of programming robots for small-sized batch production. We observe that as the complexity of assembly increases so does the likelihood of errors, and these errors need to be addressed. Nevertheless, it is essential that programming and setting up the assembly remains fast, allows quick changeovers, easy adjustments and reconfigurations. In this paper we present an initial design and implementation of extending an existing DSL for assembly operations with error specification, error handling and advanced move commands incorporating error tolerance. The DSL is used as part of a framework that aims at tackling uncertainties through a probabilistic approach.Comment: Presented at DSLRob 2014 (arXiv:cs/1411.7148

Convergent finite difference schemes for stochastic transport equations

We present difference schemes for stochastic transport equations with low-regularity velocity fields. We establish $L^2$ stability and convergence of the difference approximations under conditions that are less strict than those required for deterministic transport equations. The $L^2$ estimate, crucial for the analysis, is obtained through a discrete duality argument and a comprehensive examination of a class of backward parabolic difference schemes

Clinical and echocardiographic characteristics and cardiovascular outcomes according to diabetes status in patients with heart failure and preserved ejection fraction. A report from the Irbesartan in Heart Failure with Preserved Ejection Fraction Trial (I-Preserve)

Background—In patients with HF and preserved ejection fraction (HFpEF), little is known about the characteristics of and outcomes in those with and without diabetes. Methods—We examined clinical and echocardiographic characteristics and outcomes in the Irbesartan in Heart Failure with Preserved Ejection Fraction trial (I-Preserve), according to history of diabetes. Cox regression models were used to estimate hazard ratios (HR) for cardiovascular outcomes adjusted for known predictors, including age, sex, natriuretic peptides, and comorbidity. Echocardiographic data were available in 745 patients and were additionally adjusted for in supplementary analyses. Results—Overall, 1134 of 4128 patients (27%) had diabetes. Compared to those without diabetes, they were more likely to have a history of myocardial infarction (28% vs. 22%), higher BMI (31kg/m2 vs. 29kg/m2), worse Minnesota living with HF score (48 vs. 40), higher median NT-proBNP concentration (403 vs 320 pg/ml; all p<0.01), more signs of congestion but no significant difference in LVEF. Patients with diabetes had a greater left ventricular (LV) mass and left atrial area than patients without diabetes. Doppler E wave velocity (86 vs 76 cm/sec, p<0.0001) and the ratio of E/e' (11.7 vs 10.4, p=0.010) were higher in patients with diabetes. Over a median follow-up of 4.1 years, cardiovascular death or HF hospitalization occurred in 34% of patients with diabetes vs. 22% of those without diabetes; adjusted HR 1.75 (95% CI 1.49-2.05) and 28% vs. 19% of patients with and without diabetes died; adjusted HR 1.59 (1.33-1.91). Conclusions—In HFpEF, patients with diabetes have more signs of congestion, worse quality of life, higher NT-proBNP levels, and a poorer prognosis. They also display greater structural and functional echocardiographic abnormalities. Further investigation is needed to determine the mediators of the adverse impact of diabetes on outcomes in HFPEF, and whether they are modifiable

Simulations and Experiments on Polarisation Squeezing in Optical Fibre

We investigate polarisation squeezing of ultrashort pulses in optical fibre, over a wide range of input energies and fibre lengths. Comparisons are made between experimental data and quantum dynamical simulations, to find good quantitative agreement. The numerical calculations, performed using both truncated Wigner and exact $+P$ phase-space methods, include nonlinear and stochastic Raman effects, through coupling to phonons variables. The simulations reveal that excess phase noise, such as from depolarising GAWBS, affects squeezing at low input energies, while Raman effects cause a marked deterioration of squeezing at higher energies and longer fibre lengths. The optimum fibre length for maximum squeezing is also calculated.Comment: 19 pages, lots of figure

A pre-adaptive approach for tropical forest restoration during climate change using naturally occurring genetic variation in response to water limitation

Effective reforestation of degraded tropical forests depends on selecting planting material suited to the stressful environments typical at restoration sites that can be exacerbated by increased duration and intensity of dry spells expected with climate change. While reforestation efforts in nontropical systems are incorporating drought-adapted genotypes into restoration programs to cope with drier conditions, such approaches have not been tested or implemented in tropical forests. As the first effort to examine genetic variation in plant response to drought in a tropical wet forest, we established a watering experiment using five replicated maternal lines (i.e. seedlings from different maternal trees) of five dipterocarp species native to Borneo. Apart from the expected species level variation in growth and herbivory (3-fold variation in both cases), we also found intraspecific variation so that growth in some cases varied 2-fold, and herbivory 3-fold, among genetically different maternal lines. In two species we found that among-maternal line variation in growth rate was negatively correlated with tolerance to water limitation, that is, the maternal lines that performed the best in the high water treatment lost proportionally more of their growth during water limitation. We argue that selection for tolerance to future drier conditions is not only likely to impact population genetics of entire forests, but likely extends from forest trees to the communities of canopy arthropods associated with these trees. In tropical reforestation efforts where increased drought is predicted from climate change, including plant material resilient to drier conditions may improve restoration effectiveness