23,872 research outputs found
Group theoretical study of LOCC-detection of maximally entangled state using hypothesis testing
In the asymptotic setting, the optimal test for hypotheses testing of the
maximally entangled state is derived under several locality conditions for
measurements. The optimal test is obtained in several cases with the asymptotic
framework as well as the finite-sample framework. In addition, the experimental
scheme for the optimal test is presented
Two quantum analogues of Fisher information from a large deviation viewpoint of quantum estimation
We discuss two quantum analogues of Fisher information, symmetric logarithmic
derivative (SLD) Fisher information and Kubo-Mori-Bogoljubov (KMB) Fisher
information from a large deviation viewpoint of quantum estimation and prove
that the former gives the true bound and the latter gives the bound of
consistent superefficient estimators. In another comparison, it is shown that
the difference between them is characterized by the change of the order of
limits.Comment: LaTeX with iopart.cls, iopart12.clo, iopams.st
Asymptotic estimation theory for a finite dimensional pure state model
The optimization of measurement for n samples of pure sates are studied. The
error of the optimal measurement for n samples is asymptotically compared with
the one of the maximum likelihood estimators from n data given by the optimal
measurement for one sample.Comment: LaTeX, 23 pages, Doctoral Thesi
CIRCULAR DICHROISM OF LIGHT-HARVESTING COMPLEXES FROM PURPLE PHOTOSYNTHETIC BACTERIA
The CD spectra of a range of antenna complexes from several different species of purple photosynthetic bacteria were recorded in the wavelength range of 190 to 930 nm. Analysis of the far UV CD (190 to 250 nm) showed that in each case except for the B800-850 from Chr. vinosum the secondary structure of the light-harvesting complexes contains a large amount of α-helix (50%) and very little 0-pleated sheet. This confirms the predictions of the group of Zuber of a high a-helical content based upon consideration of the primary structures of several antenna apoproteins. The CD spectra from the carotenoids and the bacteriochlorophylls show considerable variations depending upon the type of antenna complex. The different amplitude ratios in the CD spectrum for the bacteriochlorophyll Qy, Qx and Soret bands indicate not only different degrees of exciton coupling, but also a strong and variable hyperchromism (Scherz and Parson, 1984a, b)
Comparison between the Cramer-Rao and the mini-max approaches in quantum channel estimation
In a unified viewpoint in quantum channel estimation, we compare the
Cramer-Rao and the mini-max approaches, which gives the Bayesian bound in the
group covariant model. For this purpose, we introduce the local asymptotic
mini-max bound, whose maximum is shown to be equal to the asymptotic limit of
the mini-max bound. It is shown that the local asymptotic mini-max bound is
strictly larger than the Cramer-Rao bound in the phase estimation case while
the both bounds coincide when the minimum mean square error decreases with the
order O(1/n). We also derive a sufficient condition for that the minimum mean
square error decreases with the order O(1/n).Comment: In this revision, some unlcear parts are clarifie
Error Exponent in Asymmetric Quantum Hypothesis Testing and Its Application to Classical-Quantum Channel coding
In the simple quantum hypothesis testing problem, upper bound with asymmetric
setting is shown by using a quite useful inequality by Audenaert et al,
quant-ph/0610027, which was originally invented for symmetric setting. Using
this upper bound, we obtain the Hoeffding bound, which are identical with the
classical counter part if the hypotheses, composed of two density operators,
are mutually commutative. Our upper bound improves the bound by Ogawa-Hayashi,
and also provides a simpler proof of the direct part of the quantum Stein's
lemma. Further, using this bound, we obtain a better exponential upper bound of
the average error probability of classical-quantum channel coding
Complete solution for unambiguous discrimination of three pure states with real inner products
Complete solutions are given in a closed analytic form for unambiguous
discrimination of three general pure states with real mutual inner products.
For this purpose, we first establish some general results on unambiguous
discrimination of n linearly independent pure states. The uniqueness of
solution is proved. The condition under which the problem is reduced to an
(n-1)-state problem is clarified. After giving the solution for three pure
states with real mutual inner products, we examine some difficulties in
extending our method to the case of complex inner products. There is a class of
set of three pure states with complex inner products for which we obtain an
analytical solution.Comment: 13 pages, 3 figures, presentation improved, reference adde
General theory for decoy-state quantum key distribution with arbitrary number of intensities
We develop a general theory for quantum key distribution (QKD) in both the
forward error correction and the reverse error correction cases when the QKD
system is equipped with phase-randomized coherent light with arbitrary number
of decoy intensities. For this purpose, generalizing Wang's expansion, we
derive a convex expansion of the phase-randomized coherent state. We also
numerically check that the asymptotic key generation rates are almost saturated
when the number of decoy intensities is three.Comment: This manuscript has been revised extensivel
Discrimination with error margin between two states - Case of general occurrence probabilities -
We investigate a state discrimination problem which interpolates
minimum-error and unambiguous discrimination by introducing a margin for the
probability of error. We closely analyze discrimination of two pure states with
general occurrence probabilities. The optimal measurements are classified into
three types. One of the three types of measurement is optimal depending on
parameters (occurrence probabilities and error margin). We determine the three
domains in the parameter space and the optimal discrimination success
probability in each domain in a fully analytic form. It is also shown that when
the states to be discriminated are multipartite, the optimal success
probability can be attained by local operations and classical communication.
For discrimination of two mixed states, an upper bound of the optimal success
probability is obtained.Comment: Final version, 9 pages, references added, presentation improve
The role of translational invariance in non linear gauge theories of gravity
The internal structure of the tetrads in a Poincar\'e non linear gauge theory
of gravity is considered. Minkowskian coordinates becomes dynamical degrees of
freedom playing the role of Goldstone bosons of the translations. A critical
length allowing a covariant expansion similar to the weak field approach is
deduced, the zeroth order metric being maximally symmetric (Minkowskian in some
cases).Comment: 17 pages, LaTe
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