Relations between Entanglement Witnesses and Bell Inequalities

Bell inequalities, considered within quantum mechanics, can be regarded as non-optimal witness operators. We discuss the relationship between such Bell witnesses and general entanglement witnesses in detail for the Bell inequality derived by Clauser, Horne, Shimony, and Holt (CHSH). We derive bounds on how much an optimal witness has to be shifted by adding the identity operator to make it positive on all states admitting a local hidden variable model. In the opposite direction, we obtain tight bounds for the maximal proportion of the identity operator that can be subtracted from such a CHSH witness, while preserving the witness properties. Finally, we investigate the structure of CHSH witnesses directly by relating their diagonalized form to optimal witnesses of two different classes.Comment: 8 pages, 2 figure

An industrial hygiene survey of acetonitrile using a miniature quadrupole mass spectrometer

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 33-35).Issued also on microfiche from Lange Micrographics.Charcoal tubes are an industry standard for the collection and concentration of airborne chemicals in the field for later analysis in a laboratory. There are a few drawbacks in using charcoal tubes, including the time delay before results are returned, breakthrough potential, and interferences. It is often impractical or impossible to observe a time history of contamination concentration. New technological advances have made it possible to miniaturize instruments typically found in the laboratory, such as the mass spectrometer. These advances include recent development of a miniature multipole mass spectrometer that may be useful for direct measurement of contamination in the field. Two goals were achieved in this research. First, the potential for worker exposure to acetonitrile vapors during the cleaning of a DNA-synthesizing process was demonstrated. Second, acetonitrile concentrations were measured from Tedlar bags filled in an organics-contaminated work environment and other bags with synthetic atmospheres. A miniature multinode mass spectrometer is compared with NIOSH method 1606 analysis of charcoal tubes through which the contaminated air passed while the bags were emptied. Workplace air samples, along with studies of the ventilation patterns, showed potentially unacceptable worker exposure to acetonitrile. The hazardous DNA-synthesis process was shut down pending process improvements. The multipole mass spectrometer provided readings that did not have a consistent relationship with their associated charcoal tube readings. Background readings, which included varying concentrations of environmental contaminants, needed to be subtracted, increasing variance in readings due to the high variance observed in the background readings

Bounds for state-dependent quantum cloning

Due to the no-cloning theorem, the unknown quantum state can only be cloned approximately or exactly with some probability. There are two types of cloners: universal and state-dependent cloner. The optimal universal cloner has been found and could be viewed as a special state-dependent quantum cloner which has no information about the states. In this paper, we investigate the state-dependent cloning when the state-set contains more than two states. We get some bounds of the global fidelity for these processes. This method is not dependent on the number of the states contained in the state-set. It is also independent of the numbers of copying.Comment: 13 pages, 1 figure, to appear in Phys. Rev.

Local‐Regional Similarity in Drylands Increases During Multiyear Wet and Dry Periods and in Response to Extreme Events

Climate change is predicted to impact ecosystems through altered precipitation (PPT) regimes. In the Chihuahuan Desert, multiyear wet and dry periods and extreme PPT pulses are the most influential climatic events for vegetation. Vegetation responses are most frequently studied locally, and regional responses are often unclear. We present an approach to quantify correlation of PPT and vegetation responses (as Normalized Difference Vegetation Index [NDVI]) at the Jornada ARS‐LTER site (JRN; 550 km2 area) and the surrounding dryland region (from 0 to 500 km distance; 400,000 km2 study area) as a way to understand regional similarity to locally observed patterns. We focused on fluctuating wet and dry years, multiyear wet or dry periods of 3–4 yr, and multiyear wet periods that contained one or more extreme high PPT pulses or extreme low rainfall. In all but extreme high PPT years, JRN PPT was highly correlated... (See article for full abstract)

Defect-Driven Shape Instabilities of Bundles

Topological defects are crucial to the thermodynamics and structure of condensed matter systems. For instance, when incorporated into crystalline membranes like graphene, disclinations with positive and negative topological charge elastically buckle the material into conical and saddlelike shapes, respectively. A recently uncovered mapping between the interelement spacing in 2D columnar structures and the metric properties of curved surfaces motivates basic questions about the interplay between defects in the cross section of a columnar bundle and its 3D shape. Such questions are critical to the structure of a broad class of filamentous materials, from biological assemblies like protein fibers to nanostructured or microstructured synthetic materials like carbon nanotube bundles. Here, we explore the buckling behavior for elementary disclinations in hexagonal bundles using a combination of continuum elasticity theory and numerical simulations of discrete filaments. We show that shape instabilities are controlled by a single materialdependent parameter that characterizes the ratio of interfilament to intrafilament elastic energies. Along with a host of previously unknown shape equilibria—the filamentous analogs to the conical and saddlelike shapes of defective membranes—we find a profoundly asymmetric response to positive and negative topologically charged defects in the infinite length limit that is without parallel to the membrane analog. The highly nonlinear dependence on the sign of the disclination charge is shown to have a purely geometric origin, stemming from the distinct compatibility (or incompatibility) of effectively positive- (or negative-) curvature geometries with lengthwise-constant filament spacing

Quantum Cloning of Mixed States in Symmetric Subspace

Quantum cloning machine for arbitrary mixed states in symmetric subspace is proposed. This quantum cloning machine can be used to copy part of the output state of another quantum cloning machine and is useful in quantum computation and quantum information. The shrinking factor of this quantum cloning achieves the well-known upper bound. When the input is identical pure states, two different fidelities of this cloning machine are optimal.Comment: Revtex, 4 page