39,089 research outputs found
Matter wave quantum dots (anti-dots) in ultracold atomic Bose-Fermi mixtures
The properties of ultracold atomic Bose-Fermi mixtures in external potentials
are investigated and the existence of gap solitons of Bose-Fermi mixtures in
optical lattices demonstrated. Using a self-consistent approach we compute the
energy spectrum and show that gap solitons can be viewed as matter wave
realizations of quantum dots (anti-dots) with the bosonic density playing the
role of trapping (expulsive) potential for the fermions. The fermionic states
trapped in the condensate are shown to be at the bottom of the Fermi sea and
therefore well protected from thermal decoherence. Energy levels, filling
factors and parameters dependence of gap soliton quantum dots are also
calculated both numerically and analytically.Comment: Extended version of talk given at the SOLIBEC conference, Almagro,
Spain, 8-12 February 2005. To be published on Phys.Rev.
Selecting the rank of truncated SVD by Maximum Approximation Capacity
Truncated Singular Value Decomposition (SVD) calculates the closest rank-
approximation of a given input matrix. Selecting the appropriate rank
defines a critical model order choice in most applications of SVD. To obtain a
principled cut-off criterion for the spectrum, we convert the underlying
optimization problem into a noisy channel coding problem. The optimal
approximation capacity of this channel controls the appropriate strength of
regularization to suppress noise. In simulation experiments, this information
theoretic method to determine the optimal rank competes with state-of-the art
model selection techniques.Comment: 7 pages, 5 figures; Will be presented at the IEEE International
Symposium on Information Theory (ISIT) 2011. The conference version has only
5 pages. This version has an extended appendi
Identifying the Information Gain of a Quantum Measurement
We show that quantum-to-classical channels, i.e., quantum measurements, can
be asymptotically simulated by an amount of classical communication equal to
the quantum mutual information of the measurement, if sufficient shared
randomness is available. This result generalizes Winter's measurement
compression theorem for fixed independent and identically distributed inputs
[Winter, CMP 244 (157), 2004] to arbitrary inputs, and more importantly, it
identifies the quantum mutual information of a measurement as the information
gained by performing it, independent of the input state on which it is
performed. Our result is a generalization of the classical reverse Shannon
theorem to quantum-to-classical channels. In this sense, it can be seen as a
quantum reverse Shannon theorem for quantum-to-classical channels, but with the
entanglement assistance and quantum communication replaced by shared randomness
and classical communication, respectively. The proof is based on a novel
one-shot state merging protocol for "classically coherent states" as well as
the post-selection technique for quantum channels, and it uses techniques
developed for the quantum reverse Shannon theorem [Berta et al., CMP 306 (579),
2011].Comment: v2: new result about non-feedback measurement simulation, 45 pages, 4
figure
Hot-pressing process modeling for medium density fiberboard (MDF)
In this paper we present a numerical solution for the mathematical modeling
of the hot-pressing process applied to medium density fiberboard. The model is
based in the work of Humphrey[82], Humphrey and Bolton[89] and Carvalho and
Costa[98], with some modifications and extensions in order to take into account
mainly the convective effects on the phase change term and also a conservative
numerical treatment of the resulting system of partial differential equations.Comment: LaTeX, 11 figures. Added references. Fixed some errors. To appear in
International Journal of Mathematics and Mathematical Sciences,
http://jam.hindawi.co
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