4,141 research outputs found
Joint measurability, steering and entropic uncertainty
The notion of incompatibility of measurements in quantum theory is in stark
contrast with the corresponding classical perspective, where all physical
observables are jointly measurable. It is of interest to examine if the results
of two or more measurements in the quantum scenario can be perceived from a
classical point of view or they still exhibit non-classical features. Clearly,
commuting observables can be measured jointly using projective measurements and
their statistical outcomes can be discerned classically. However, such simple
minded association of compatibility of measurements with commutativity turns
out to be limited in an extended framework, where the usual notion of sharp
projective valued measurements of self adjoint observables gets broadened to
include unsharp measurements of generalized observables constituting positive
operator valued measures (POVM). There is a surge of research activity recently
towards gaining new physical insights on the emergence of classical behavior
via joint measurability of unsharp observables. Here, we explore the entropic
uncertainty relation for a pair of discrete observables (of Alice's system)
when an entangled quantum memory of Bob is restricted to record outcomes of
jointly measurable POVMs only. Within the joint measurability regime, the sum
of entropies associated with Alice's measurement outcomes - conditioned by the
results registered at Bob's end - are constrained to obey an entropic steering
inequality. In this case, Bob's non-steerability reflects itself as his
inability in predicting the outcomes of Alice's pair of non-commuting
observables with better precision, even when they share an entangled state. As
a further consequence, the quantum advantage envisaged for the construction of
security proofs in key distribution is lost, when Bob's measurements are
restricted to the joint measurability regime.Comment: 5 pages, RevTeX, 1 pdf figure, Comments welcom
Joint Measurability and Temporal Steering
Quintino et. al. (Phys. Rev. Lett. 113, 160402 (2014)) and Uola et. al.
(Phys. Rev. Lett. 113, 160403 (2014)) have recently established an intrinsic
relation between non-joint measurability and Einstein-Podolsky- Rosen steering.
They showed that a set of measurements is incompatible (i.e., not jointly
measurable) if and only if it can be used for the demonstration of steering. In
this paper, we prove the temporal analog of this result viz., a set of
measurements are incompatible if and only if it exhibits temporal steering.Comment: 6 pages,no figures, typos corrected, improved presentation; To appear
in JOSA B feature issue "80 years of Steering and the Einstein-Podolsky-Rosen
Paradox
Impact of Information and Communication Technology on Library and its Services
The advancement of science and technology has made a tremendous improvement and change almost in all walks of life. Especially the magnetic word Information technology has been chanted in all corners of the global arena. The paper highlights the changing dimensions of library services due to the impact of ICT. The various aspects of digital library, its purpose and advantages are talked about. The most essential features such as infrastructure, staff support and budgetary aspects are also discussed with respect to Indian context
Human otoacariasis: a common outbreak in rubber growing belt of Karnataka.
Background/Objective: Soft tick in the ear is a very common acute painful and distressing condition in the flowering months of October to March. It’s a common condition in the rubber growing belt of Sullia.The mouthparts of the tick grips firmly the skin of the external auditory canal or the tympanic membrane and sucks blood and swells up. Otoscopy and removal of the tick from the ear can be done in outpatients in adults and difficult in a frightened irritable child.Materials and methods: 312 cases of intra-aural ticks presenting to the opd and casualty which included 131 males and 181 females were included in the study.Results: Out of the 312 cases of intra-aural ticks, 170 cases were treated in the outpatient and 140 cases under short general anesthesia with oto-microscopy.Conclusion: Intra-aural tick infestation is an acute painful condition which needs prompt management by an experienced otolaryngologist. Proper visualization and instrumentation is necessary to avoid complications.
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