1,899 research outputs found
Violation of Entropic Leggett-Garg Inequality in Nuclear Spins
We report an experimental study of recently formulated entropic Leggett-Garg
inequality (ELGI) by Usha Devi et al. (arXiv: 1208.4491v2 (2012)). This
inequality places a bound on the statistical measurement outcomes of dynamical
observables describing a macrorealistic system. Such a bound is not necessarily
obeyed by quantum systems, and therefore provides an important way to
distinguish quantumness from classical behavior. Here we study ELGI using a
two-qubit nuclear magnetic resonance system. To perform the noninvasive
measurements required for the ELGI study, we prepare the system qubit in a
maximally mixed state as well as use the `ideal negative result measurement'
procedure with the help of an ancilla qubit. The experimental results show a
clear violation of ELGI by over four standard deviations. These results agree
with the predictions of quantum theory. The violation of ELGI is attributed to
the fact that certain joint probabilities are not legitimate in the quantum
scenario, in the sense they do not reproduce all the marginal probabilities.
Using a three-qubit system, we experimentally demonstrate that three-time joint
probabilities do not reproduce certain two-time marginal probabilities.Comment: 5 pages, 5 figures, 1 page supplementar
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
Etiology of tooth discoloration- a review
Discoloration of the tooth can erode the sparkle from a smile. In the management of patients with discolored tooth, knowledge of the mechanisms behind tooth discoloration is of relevance as it can influence the treatment plan. In certain instances it may even have an effect on the outcome of the treatment. A grasp of the pathological process involved in tooth staining will also allow the dental practitioner to explain to the patient the exact nature of the condition. An overview of the etiology and the clinical appearance of tooth discoloration are discussed in this review
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