2,465 research outputs found
Infinite Correlation in Measured Quantum Processes
We show that quantum dynamical systems can exhibit infinite correlations in
their behavior when repeatedly measured. We model quantum processes using
quantum finite-state generators and take the stochastic language they generate
as a representation of their behavior. We analyze two spin-1 quantum systems
that differ only in how they are observed. The corresponding language generated
has short-range correlation in one case and infinite correlation in the other.Comment: 2 pages, 2 figure
Computation in Finitary Stochastic and Quantum Processes
We introduce stochastic and quantum finite-state transducers as
computation-theoretic models of classical stochastic and quantum finitary
processes. Formal process languages, representing the distribution over a
process's behaviors, are recognized and generated by suitable specializations.
We characterize and compare deterministic and nondeterministic versions,
summarizing their relative computational power in a hierarchy of finitary
process languages. Quantum finite-state transducers and generators are a first
step toward a computation-theoretic analysis of individual, repeatedly measured
quantum dynamical systems. They are explored via several physical systems,
including an iterated beam splitter, an atom in a magnetic field, and atoms in
an ion trap--a special case of which implements the Deutsch quantum algorithm.
We show that these systems' behaviors, and so their information processing
capacity, depends sensitively on the measurement protocol.Comment: 25 pages, 16 figures, 1 table; http://cse.ucdavis.edu/~cmg; numerous
corrections and update
Self heating and nonlinear current-voltage characteristics in bilayer graphene
We demonstrate by experiments and numerical simulations that the
low-temperature current-voltage characteristics in diffusive bilayer graphene
(BLG) exhibit a strong superlinearity at finite bias voltages. The
superlinearity is weakly dependent on doping and on the length of the graphene
sample. This effect can be understood as a result of Joule heating. It is
stronger in BLG than in monolayer graphene (MLG), since the conductivity of BLG
is more sensitive to temperature due to the higher density of electronic states
at the Dirac point.Comment: 9 pages, 7 figures, REVTeX 4.
Klinische Erfahrungen mit einem Ergocalciferol- und Vitamin C-haltigen Kalziumpräparat zur Prophylaxe und Therapie von Skeletterkrankungen junger Affen
Durch die ausschlieĂźlich prophylaktische Anwendung
eines Ergocalciferol- und Vitamin-Chaltigen
Calciumpräparates konnte in einem
ĂĽber 3 Jahre laufenden Versuch bei 6 jungen
Menschenaffen die Entstehung metabolischer
Knochenveränderungen verhindert werden.
AuĂźerdem wird ĂĽber gute therapeutische Erfahrungen
bei Affen mit Osteopathien, sowie
tetanischen — und allergischen Krankheitsbildern
kurz berichtet
Using mutual information to measure order in model glass-formers
Whether or not there is growing static order accompanying the dynamical
heterogeneity and increasing relaxation times seen in glassy systems is a
matter of dispute. An obstacle to resolving this issue is that the order is
expected to be amorphous and so not amenable to simple order parameters. We use
mutual information to provide a general measurement of order that is sensitive
to multi-particle correlations. We apply this to two glass-forming systems (2D
binary mixtures of hard disks with different size ratios to give varying
amounts of hexatic order) and show that there is little growth of amorphous
order in the system without crystalline order. In both cases we measure the
dynamical length with a four-point correlation function and find that it
increases significantly faster than the static lengths in the system as density
is increased. We further show that we can recover the known scaling of the
dynamic correlation length in a kinetically constrained model, the 2-TLG.Comment: 10 pages, 12 Figure
Intrinsic Quantum Computation
We introduce ways to measure information storage in quantum systems, using a
recently introduced computation-theoretic model that accounts for measurement
effects. The first, the quantum excess entropy, quantifies the shared
information between a quantum process's past and its future. The second, the
quantum transient information, determines the difficulty with which an observer
comes to know the internal state of a quantum process through measurements. We
contrast these with von Neumann entropy and quantum entropy rate and provide a
closed-form expression for the latter for the class of deterministic quantum
processes.Comment: 5 pages, 1 figure, 1 table; updated with corrections;
http://cse.ucdavis.edu/~cmg/compmech/pubs/iqc.ht
Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass
The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment
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