892 research outputs found
Sudden change in dynamics of genuine multipartite entanglement of cavity-reservoir qubits
We study the dynamics of genuine multipartite entanglement for a system of
four qubits. Using a computable entanglement monotone for multipartite systems,
we investigate the as yet unexplored aspects of a cavity-reservoir system of
qubits. For one specific initial state, we observe a sudden transition in the
dynamics of genuine entanglement for the four qubits. This sudden change occurs
only during a time window where neither cavity-cavity qubits nor
reservoir-reservoir qubits are entangled. We show that this sudden change in
dynamics of this specific state is extremely sensitive to white noise.Comment: 18 pages, 11 figure
The Jamio{\l}kowski isomorphism and a conceptionally simple proof for the correspondence between vectors having Schmidt number and -positive maps
Positive maps which are not completely positive are used in quantum
information theory as witnesses for convex sets of states, in particular as
entanglement witnesses and more generally as witnesses for states having
Schmidt number not greater than k. It is known that such witnesses are related
to k-positive maps. In this article we propose a new proof for the
correspondence between vectors having Schmidt number k and k-positive maps
using Jamiolkowski's criterion for positivity of linear maps; to this aim, we
also investigate the precise notion of the term "Jamiolkowski isomorphism". As
consequences of our proof we get the Jamiolkowski criterion for complete
positivity, and we find a special case of a result by Choi, namely that
k-positivity implies complete positivity, if k is the dimension of the smaller
one of the Hilbert spaces on which the operators act.Comment: 9 page
Electronic structure basis for the titanic magnetoresistance in WTe
The electronic structure basis of the extremely large magnetoresistance in
layered non-magnetic tungsten ditelluride has been investigated by
angle-resolved photoelectron spectroscopy. Hole and electron pockets of
approximately the same size were found at the Fermi level, suggesting that
carrier compensation should be considered the primary source of the effect. The
material exhibits a highly anisotropic, quasi one-dimensional Fermi surface
from which the pronounced anisotropy of the magnetoresistance follows. A change
in the Fermi surface with temperature was found and a high-density-of-states
band that may take over conduction at higher temperatures and cause the
observed turn-on behavior of the magnetoresistance in WTe was identified
Demonstration of the CDMA-mode CAOS smart camera
Demonstrated is the code division multiple access (CDMA)-mode coded access optical sensor (CAOS) smart camera suited for bright target scenarios. Deploying a silicon CMOS sensor and a silicon point detector within a digital micro-mirror device (DMD)-based spatially isolating hybrid camera design, this smart imager first engages the DMD starring mode with a controlled factor of 200 high optical attenuation of the scene irradiance to provide a classic unsaturated CMOS sensor-based image for target intelligence gathering. Next, this CMOS sensor provided image data is used to acquire a focused zone more robust un-attenuated true target image using the time-modulated CDMA-mode of the CAOS camera. Using four different bright light test target scenes, successfully demonstrated is a proof-of-concept visible band CAOS smart camera operating in the CDMA-mode using up-to 4096 bits length Walsh design CAOS pixel codes with a maximum 10 KHz code bit rate giving a 0.4096 seconds CAOS frame acquisition time. A 16-bit analog-to-digital converter (ADC) with time domain correlation digital signal processing (DSP) generates the CDMA-mode images with a 3600 CAOS pixel count and a best spatial resolution of one micro-mirror square pixel size of 13.68 μm side. The CDMA-mode of the CAOS smart camera is suited for applications where robust high dynamic range (DR) imaging is needed for un-attenuated un-spoiled bright light spectrally diverse targets
177 dB linear dynamic range pixels of interest DSLR CAOS camera
For the first time, demonstrated is an extreme linear Dynamic Range (DR) Pixels of Interest (POI) [i.e., Coded Access Optical Sensor (CAOS)] Digital Single Lens Reflex (DSLR) camera design that engages three different types of photosensors within one optomechanical assembly to smartly identify POI across a one billion to one light irradiance range. A pixelated CMOS sensor provides a limited DR and linearity image by engaging a moveable mirror placed between the Digital Micromirror Device (DMD) and the frontend imaging lens. Next using DMD control, non-POI light is directed away from the chosen point photodetector (PD) engaged for high DR POI image recovery, giving the PD an improved use of quantum well capacity. For brighter POI, a solid state photodiode point PD with an electronic gain controlled amplifier is engaged while for weaker light POI, a photomultiplier tube (PMT) with variable optical gain is deployed. POI imaging is achieved using time-frequency CAOS modes via DMD control and time-frequency correlation and spectral digital signal processing. A 123.4 dB linear DR POI recovery is achieved for a custom incoherent white light 36-patch target while a record 177 dB linear DR recovery is demonstrated for a single patch 633 nm laser target. For the first time, a 1023 POI frame, real-time 48 frames/s update rate CAOS imaging is demonstrated for tracking a changing focal spot moving laser target
Relationship between visual prostate score (VPSS) and maximum flow rate (Qmax) in men with urinary tract symptoms
Abstract OBJECTIVE:
To evaluate correlation between visual prostate score (VPSS) and maximum flow rate (Qmax) in men with lower urinary tract symptoms. MATERIAL AND METHODS:
This is a cross sectional study conducted at a university Hospital. Sixty-seven adult male patients\u3e50 years of age were enrolled in the study after signing an informed consent. Qmax and voided volume recorded at uroflowmetry graph and at the same time VPSS were assessed. The education level was assessed in various defined groups. Pearson correlation coefficient was computed for VPSS and Qmax. RESULTS:
Mean age was 66.1±10.1 years (median 68). The mean voided volume on uroflowmetry was 268±160mL (median 208) and the mean Qmax was 9.6±4.96mLs/sec (median 9.0). The mean VPSS score was 11.4±2.72 (11.0). In the univariate linear regression analysis there was strong negative (Pearson\u27s) correlation between VPSS and Qmax (r=-848, p\u3c0.001). In the multiple linear regression analyses there was a significant correlation between VPSS and Qmax (β-http://www.blogapaixonadosporviagens.com.br/p/caribe.html after adjusting the effect of age, voided volume (V.V) and level of education. Multiple linear regression analysis done for independent variables and results showed that there was no significant correlation between the VPSS and independent factors including age (p=0.27), LOE (p=0.941) and V.V (p=0.082). CONCLUSION:
There is a significant negative correlation between VPSS and Qmax. The VPSS can be used in lieu of IPSS score. Men even with limited educational background can complete VPSS without assistance
Characteristics of an adult photosensitive cohort
Intermittent Photic Stimulation (IPS) is a well recognized provocation maneuver during EEG recording which helps in identifying underlying photosensitivity. The frequency and characteristics of various responses to photosensitivity among our adult patients was determine. EEGs of subjects \u3e or =15 years from 2003-2006, were reviewed. Two main photosensitive responses were observed: Photoparoxysmal (PPR) and Photic-driving response (PDR). Demographic and clinical data was also collected. Out of 5950 EEG\u27s performed, response to IPS were detected in 1.2% (n=73) of EEGs. Out of which 49 (67%) had PDR and 24 (33%) had PPR. Mean age of PPR group was 25.7 +/- 12 years with equal gender distribution. In PPR subjects, epilepsy was the final EEG conclusion in majority of patients 96% (n=23) p-value \u3c 0.001. Primary Generalized Epilepsy being the most common 52% (n=12). In contrast, PDR observed in normal EEG\u27s was 45% (n=22). This study revealed low frequency 1.2% of photosensitive responses. PPR is seen frequently in patients with epilepsy (96%, p-value \u3c 0.001), and highest rate (52%) of photosensitivity was observed in patients with primary generalized epilepsy
Quantum discord for two-qubit X states
Quantum discord, a kind of quantum correlation, is defined as the difference between quantum mutual information and classical correlation in a bipartite system. In general, this correlation is different from entanglement, and quantum discord may be nonzero even for certain separable states. Even in the simple case of bipartite quantum systems, this different kind of quantum correlation has interesting and significant applications in quantum information processing. So far, quantum discord has been calculated explicitly only for a rather limited set of two-qubit quantum states and expressions for more general quantum states are not known. In this article, we derive explicit expressions for quantum discord for a larger class of two-qubit states, namely, a seven-parameter family of so called X states that have been of interest in a variety of contexts in the field. We also study the relation between quantum discord, classical correlation, and entanglement for a number of two-qubit states to demonstrate that they are independent measures of correlation with no simple relative ordering between them. © 2010 The American Physical Society
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