2,927 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
Inversion of moments to retrieve joint probabilities in quantum sequential measurements
A sequence of moments encode the corresponding probability distribution.
Probing if quantum joint probability distribution can be retrieved from the
associated set of moments -- realized in the sequential measurement of a
dichotomic observable at different time intervals -- reveals a negative answer
i.e., the joint probabilities of sequential measurements do not agree with the
ones obtained by inverting the moments. This is indeed a reflection of the
non-existence of a bonafide grand joint probability distribution, consistent
with all the physical marginal probability distributions. Here we explicitly
demonstrate that given the set of moments, it is not possible to retrieve the
three-time quantum joint probability distribution resulting from quantum
sequential measurement of a single qubit dichotomic observable at three
different times. Experimental results using a nuclear magnetic resonance (NMR)
system are reported here to corroborate these theoretical observations viz.,
the incompatibility of the three-time joint probabilties with those extracted
from the moment sequence.Comment: 7 pages, 5 figures, RevTe
Production & characterization of monoclonal antibodies to Mycobacterium tuberculosis
Background & objectives: Monoclonal antibodies (MAbs) against Mycobacterium tuberculosis H37Rv culture
filtrate (CF) were raised by immunizing BALB/c mice and characterization was done. Attempts have been
directed towards identifying mycobacterial antigens in biological fluids by employing polyclonal and monoclonal
antibodies specific for M. tuberculosis. Immunohistologic studies, using MAbs for the localization of whole or
fragmented bacilli in the biopsy specimens were also carried out.
Methods: Intrasplenic IS and intraperitoneal IP routes of immunization, were compared. The MAbs were
characterized for their isotype, binding specificity, nature of binding epitope, reactivity in immunoassays etc.
Results: IS and IF’ routes of immunization, were compared and IP was found superior. Ten MAbs designated
TRC l-10 were produced. Of these, 7 MAbs, TRC 1-7 reacted with the 30/31 kDa doublet (antigen 85 complex),
TRC 8 with 12 kDa in addition to 30/31 kDa and TRC 9 and 10 with the 24 and 12 kDa antigens respectively.
Six MAbs were classified as broadly cross reactive and 2 showed limited cross reactivity. TRC 8 and 10 showed
species specificity. Employing TRC 8 in sandwich ELISA, antigen was detected in sera from 17 of 25 pulmonary
tuberculosis patients and 3 of 20 controls. TRC 8 was found to be useful in detecting antigens specifically in
M. tuberculosis and M. leprae infected tissues, by immunoperoxidase staining.
Interpretation & conclusion: TRC 8 was found to be restricted in its reactivity to M. tuberculosis complex and
M, leprae. TRC 8 may prove useful in immuno-diagnosis of tuberculosis
Time-dependent Hartree-Fock theory of charge exchange: Application to He2+ + He
An application of the time-dependent Hartree-Fock (TDHF) theory of charge transfer in atomic collisions is presented. Probabilities for elastic and double symmetric charge exchange are calculated for a fixed laboratory scattering angle and for collision energies from 10 to 70 keV. The TDHF equations are solved using finite difference techniques and propagated in time using the Peaceman-Rachford alternating-direction implicit method. Plots of time-evolved charge densities are presented also
Isolation and Evaluation of Diagnostic Value of Two Major Secreted Proteins of Mycobacterium Tuberculosis
Two secreted antigens of Mycobacterium tuberculosis, namely the antigen 85 complex (30/31) and
38kDa antigens, were purified from the whole culture filtrate by using two dimensional
preparative electrophoresis and anion exchange chromatography, respectively. Individual
components of the antigen 85 complex namely, antigen 85A, 85B and 85C, were separated using
hydrophobic interaction chromatography. The humoral antibody activity to these antigens in
sputum positive cases of active pulmonary tuberculosis and normal healthy volunteers was
determined by enzyme linked immunosorbent assay (ELISA) and immunoblot. Recombinant
38kDa and antigen 6 were used as reference antigens for the assay. None of the healthy
volunteers reacted with the 38kDa antigen, while 52% of the TB sera reacted with it. Of the three
components of the antigen 85 complex, 85B gave the highest positivity of 40 per cent. The results
of combination of 38kDa with antigen 6 offered better results with 76% positivity
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