21,251 research outputs found
Fibonacci-Lucas SIC-POVMs
We present a conjectured family of SIC-POVMs which have an additional
symmetry group whose size is growing with the dimension. The symmetry group is
related to Fibonacci numbers, while the dimension is related to Lucas numbers.
The conjecture is supported by exact solutions for dimensions
d=4,8,19,48,124,323, as well as a numerical solution for dimension d=844.Comment: The fiducial vectors can be obtained from
http://sicpovm.markus-grassl.de as well as from the source files. v2:
precision for the numerical solution in dimension 844 increased to 150 digits
and new exact solution for dimension 323 adde
Complex Obtuse Random Walks and their Continuous-Time Limits
We study a particular class of complex-valued random variables and their
associated random walks: the complex obtuse random variables. They are the
generalization to the complex case of the real-valued obtuse random variables
which were introduced in \cite{A-E} in order to understand the structure of
normal martingales in \RR^n.The extension to the complex case is mainly
motivated by considerations from Quantum Statistical Mechanics, in particular
for the seek of a characterization of those quantum baths acting as classical
noises. The extension of obtuse random variables to the complex case is far
from obvious and hides very interesting algebraical structures. We show that
complex obtuse random variables are characterized by a 3-tensor which admits
certain symmetries which we show to be the exact 3-tensor analogue of the
normal character for 2-tensors (i.e. matrices), that is, a necessary and
sufficient condition for being diagonalizable in some orthonormal basis. We
discuss the passage to the continuous-time limit for these random walks and
show that they converge in distribution to normal martingales in \CC^N. We
show that the 3-tensor associated to these normal martingales encodes their
behavior, in particular the diagonalization directions of the 3-tensor indicate
the directions of the space where the martingale behaves like a diffusion and
those where it behaves like a Poisson process. We finally prove the
convergence, in the continuous-time limit, of the corresponding multiplication
operators on the canonical Fock space, with an explicit expression in terms of
the associated 3-tensor again
On the Law of Addition of Random Matrices
Normalized eigenvalue counting measure of the sum of two Hermitian (or real
symmetric) matrices and rotated independently with respect to
each other by the random unitary (or orthogonal) Haar distributed matrix
(i.e. ) is studied in the limit of large
matrix order . Convergence in probability to a limiting nonrandom measure is
established. A functional equation for the Stieltjes transform of the limiting
measure in terms of limiting eigenvalue measures of and is
obtained and studied.
Keywords: random matrices, eigenvalue distributionComment: 41 pages, submitted to Commun. Math. Phy
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