357 research outputs found
Bayesian parameter estimation with prior weighting in ALT model
This paper provides an overview of the application of Bayesian inference to accelerated life testing (ALT) models for the concrete case of estimation by Maximum of Aposteriori (MAP) method in the case of constant stress levels. It studies the Bayesian inference over the accelerated life model as presented in [1]. It suites, integrates and generalizes the particular cases presented in [2] and [3]. Towards the end, weighting of the prior information according to data is integrated. The paper also illustrates an experimental example
Eigenvalues and Singular Values of Products of Rectangular Gaussian Random Matrices
We derive exact analytic expressions for the distributions of eigenvalues and
singular values for the product of an arbitrary number of independent
rectangular Gaussian random matrices in the limit of large matrix dimensions.
We show that they both have power-law behavior at zero and determine the
corresponding powers. We also propose a heuristic form of finite size
corrections to these expressions which very well approximates the distributions
for matrices of finite dimensions.Comment: 13 pages, 3 figure
Topology and Phases in Fermionic Systems
There can exist topological obstructions to continuously deforming a gapped
Hamiltonian for free fermions into a trivial form without closing the gap.
These topological obstructions are closely related to obstructions to the
existence of exponentially localized Wannier functions. We show that by taking
two copies of a gapped, free fermionic system with complex conjugate
Hamiltonians, it is always possible to overcome these obstructions. This allows
us to write the ground state in matrix product form using Grassman-valued bond
variables, and show insensitivity of the ground state density matrix to
boundary conditions.Comment: 4 pages, see also arxiv:0710.329
Complete diagrammatics of the single ring theorem
Using diagrammatic techniques, we provide explicit functional relations
between the cumulant generating functions for the biunitarily invariant
ensembles in the limit of large size of matrices. The formalism allows to map
two distinct areas of free random variables: Hermitian positive definite
operators and non-normal R-diagonal operators. We also rederive the
Haagerup-Larsen theorem and show how its recent extension to the eigenvector
correlation function appears naturally within this approach.Comment: 18 pages, 6 figures, version accepted for publicatio
Spectral measures of small index principal graphs
The principal graph of a subfactor with finite Jones index is one of the
important algebraic invariants of the subfactor. If is the adjacency
matrix of we consider the equation . When has square
norm the spectral measure of can be averaged by using the map
, and we get a probability measure on the unit circle
which does not depend on . We find explicit formulae for this measure
for the principal graphs of subfactors with index , the
(extended) Coxeter-Dynkin graphs of type , and . The moment
generating function of is closely related to Jones' -series.Comment: 23 page
Collective potential for large N hamiltonian matrix models and free Fisher information
We formulate the planar `large N limit' of matrix models with a continuously
infinite number of matrices directly in terms of U(N) invariant variables.
Non-commutative probability theory, is found to be a good language to describe
this formulation. The change of variables from matrix elements to invariants
induces an extra term in the hamiltonian,which is crucual in determining the
ground state. We find that this collective potential has a natural meaning in
terms of non-commutative probability theory:it is the `free Fisher information'
discovered by Voiculescu. This formulation allows us to find a variational
principle for the classical theory described by such large N limits. We then
use the variational principle to study models more complex than the one
describing the quantum mechanics of a single hermitian matrix (i.e., go beyond
the so called D=1 barrier). We carry out approximate variational calculations
for a few models and find excellent agreement with known results where such
comparisons are possible. We also discover a lower bound for the ground state
by using the non-commutative analogue of the Cramer-Rao inequality.Comment: 25 pages, late
Error analysis of free probability approximations to the density of states of disordered systems
Theoretical studies of localization, anomalous diffusion and ergodicity
breaking require solving the electronic structure of disordered systems. We use
free probability to approximate the ensemble- averaged density of states
without exact diagonalization. We present an error analysis that quantifies the
accuracy using a generalized moment expansion, allowing us to distinguish
between different approximations. We identify an approximation that is accurate
to the eighth moment across all noise strengths, and contrast this with the
perturbation theory and isotropic entanglement theory.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Let
Bayesian Parameter Estimation with Prior Weighting in ALT Model
This paper provides an overview of the application of Bayesian inference to accelerated life testing (ALT) models for the concrete case of estimation by Maximum of Aposteriori (MAP) method in the case of constant stress levels. It studies the Bayesian inference over the accelerated life model as presented in [9]. It suites, integrates and generalizes the particular cases presented in [12] and [13]. Towards the end, weighting of the prior information according to data is integrated. The paper also illustrates an experimental example
Investigation of continuous-time quantum walk by using Krylov subspace-Lanczos algorithm
In papers\cite{js,jsa}, the amplitudes of continuous-time quantum walk on
graphs possessing quantum decomposition (QD graphs) have been calculated by a
new method based on spectral distribution associated to their adjacency matrix.
Here in this paper, it is shown that the continuous-time quantum walk on any
arbitrary graph can be investigated by spectral distribution method, simply by
using Krylov subspace-Lanczos algorithm to generate orthonormal bases of
Hilbert space of quantum walk isomorphic to orthogonal polynomials. Also new
type of graphs possessing generalized quantum decomposition have been
introduced, where this is achieved simply by relaxing some of the constrains
imposed on QD graphs and it is shown that both in QD and GQD graphs, the unit
vectors of strata are identical with the orthonormal basis produced by Lanczos
algorithm. Moreover, it is shown that probability amplitude of observing walk
at a given vertex is proportional to its coefficient in the corresponding unit
vector of its stratum, and it can be written in terms of the amplitude of its
stratum. Finally the capability of Lanczos-based algorithm for evaluation of
walk on arbitrary graphs (GQD or non-QD types), has been tested by calculating
the probability amplitudes of quantum walk on some interesting finite
(infinite) graph of GQD type and finite (infinite) path graph of non-GQD type,
where the asymptotic behavior of the probability amplitudes at infinite limit
of number of vertices, are in agreement with those of central limit theorem of
Ref.\cite{nko}.Comment: 29 pages, 4 figure
Random matrix techniques in quantum information theory
The purpose of this review article is to present some of the latest
developments using random techniques, and in particular, random matrix
techniques in quantum information theory. Our review is a blend of a rather
exhaustive review, combined with more detailed examples -- coming from research
projects in which the authors were involved. We focus on two main topics,
random quantum states and random quantum channels. We present results related
to entropic quantities, entanglement of typical states, entanglement
thresholds, the output set of quantum channels, and violations of the minimum
output entropy of random channels
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