1,331 research outputs found
Detecting mixedness of qutrit systems using the uncertainty relation
We show that the uncertainty relation as expressed in the
Robertson-Schrodinger generalized form can be used to detect the mixedness of
three-level quantum systems in terms of measureable expectation values of
suitably chosen observables when prior knowledge about the basis of the given
state is known. In particular, we demonstrate the existence of observables for
which the generalized uncertainty relation is satisfied as an equality for pure
states and a strict inequality for mixed states corresponding to single as well
as bipartite sytems of qutrits. Examples of such observables are found for
which the magnitude of uncertainty is proportional to the linear entropy of the
system, thereby providing a method for measuring mixedness.Comment: 7 pages, 2 figure, Eqs.(10) and (14) are corrected, and results and
conclusions are unchange
Fine-grained uncertainty relation and nonlocality of tripartite systems
The upper bound of the fine-grained uncertainty relation is different for
classical physics, quantum physics and no-signaling theories with maximal
nonlocality (supper quantum correlation), as was shown in the case of bipartite
systems [J. Oppenheim and S. Wehner, Science 330, 1072 (2010)]. Here, we extend
the fine-grained uncertainty relation to the case of tripartite systems. We
show that the fine-grained uncertainty relation determines the nonlocality of
tripartite systems as manifested by the Svetlichny inequality, discriminating
between classical physics, quantum physics and super quantum correlations.Comment: 4 page
Stagnation zone during the turning of Duplex SAF 2205 stainless steels alloy
Duplex stainless alloys are extremely sensitive to cutting speed for strain hardening during machining. Tool wear for these materials is dominated by the adhesion wear because of formation of built-up edge (BUE) that upsurges the flank wear considerably. In addition, flute damage is a significant problem during drilling of those alloys. To address this issue, this paper investigates the mechanism of BUE creation in stagnation region of duplex SAF 2205 alloys during material removal by turning process. The investigation of chip root through SEM and electron backscatter diffraction (EBSD) revealed build-up of ferritic bands at the stagnation zone. Higher capacity of austenite phase to deform plastically is accountable for the ferrite build-up. This was detected as a possible activating mechanism of built-up edge. The flow pattern of austenite phase designates faster deforming compare to that of ferrite phases
Size-dependent electronic-transport mechanism and sign reversal of magnetoresistance in Nd0.5Sr0.5CoO3
A detailed investigation of electronic-transport properties of Nd0.5Sr0.5CoO3
has been carried out as a function of grain size ranging from micrometer order
down to an average size of 28 nm. Interestingly, we observe a size induced
metal-insulator transition in the lowest grain size sample while the bulk-like
sample is metallic in the whole measured temperature regime. An analysis of the
temperature dependent resistivity in the metallic regime reveals that the
electron-electron interaction is the dominating mechanism while other processes
like electron-magnon and electron-phonon scatterings are also likely to be
present. The fascinating observation of enhanced low temperature upturn and
minimum in resistivity on reduction of grain size is found due to
electron-electron interaction (quantum interference effect). This effect is
attributed to enhanced disorder on reduction of grain size. Interestingly, we
observed a cross over from positive to negative magnetoresistance in the low
temperature regime as the grain size is reduced. This observed sign reversal is
attributed to enhanced phase separation on decreasing the grain size of the
cobaltite
Fine-grained lower limit of entropic uncertainty in the presence of quantum memory
The limitation on obtaining precise outcomes of measurements performed on two
non-commuting observables of a particle as set by the uncertainty principle in
its entropic form, can be reduced in the presence of quantum memory. We derive
a new entropic uncertainty relation based on fine- graining, which leads to an
ultimate limit on the precision achievable in measurements performed on two
incompatible observables in the presence of quantum memory. We show that our
derived uncertainty relation tightens the lower bound set by entropic
uncertainty for members of the class of two-qubit states with maximally mixed
marginals, while accounting for the recent experimental results using maximally
entangled pure states and mixed Bell-diagonal states. An implication of our
uncertainty relation on the security of quantum key generation protocols is
pointed out.Comment: Latex, 5 pages, one encapsulated figure, accepted for publication in
Physical Review Letter
Color vison deficieny among medical students: an unnoticed problem
ABSTRACT Color vision deficiency, most of the time remains an unnoticed problem; although it is not very rare. The faculty of appreciation of color is essential for our smooth daily activities. Unfortunately, even many doctors do not know the severity of their color vision deficiency and tend to assume it as slight, and a few, as in the general population, do not know about their disability. Some common difficulties reported by medical practitioners and medical students were in recognizing-widespread body color changes (pallor, cyanosis, jaundice, rashes, erythema of skin), colorful charts, slides, test-strips for blood and urine, body products: blood or bile in urine, faeces, sputum, vomit, microscopy, mouth and throat conditions, impressions presented in the Ishihara chart, titration end-points, tissue identification (surgery) etc. The present study was undertaken to evaluate the presence of congenital color vision deficiencies among the medical students. The study was carried out among the 1 st and 2 nd year medical students of Nepal Medical College and Teaching Hospital (n = 120) with the help of Ishihara chart, that was shown to all participants. They were asked to read the impressions in the color chart. The impression perceived by a person with normal color vision was different from the impression perceived by a person with color vision deficiency. It was noted that, among the study population (n = 120) 5.83% of the volunteers were color weak. Amongst the color-deficient volunteers, 57.0% were protanopic while 43.0% were deuteranopic. Medical students must be made aware of their congenital color vision deficiency and its effects on their work. Screening will enable the student and later the doctor to become aware of limitations in their powers of observation and devise ways of overcoming them; the patient will be protected from harm and litigation may be avoided when doctors have adapted their practice to their deficiency. Medical students and physicians must be screened for color vision deficiency and advised about it so they can take special care in clinical practice
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