10,193 research outputs found
On the capacities of bipartite Hamiltonians and unitary gates
We consider interactions as bidirectional channels. We investigate the
capacities for interaction Hamiltonians and nonlocal unitary gates to generate
entanglement and transmit classical information. We give analytic expressions
for the entanglement generating capacity and entanglement-assisted one-way
classical communication capacity of interactions, and show that these
quantities are additive, so that the asymptotic capacities equal the
corresponding 1-shot capacities. We give general bounds on other capacities,
discuss some examples, and conclude with some open questions.Comment: V3: extensively rewritten. V4: a mistaken reference to a conjecture
by Kraus and Cirac [quant-ph/0011050] removed and a mistake in the order of
authors in Ref. [53] correcte
Stochastic Reinforcement Learning
In reinforcement learning episodes, the rewards and punishments are often
non-deterministic, and there are invariably stochastic elements governing the
underlying situation. Such stochastic elements are often numerous and cannot be
known in advance, and they have a tendency to obscure the underlying rewards
and punishments patterns. Indeed, if stochastic elements were absent, the same
outcome would occur every time and the learning problems involved could be
greatly simplified. In addition, in most practical situations, the cost of an
observation to receive either a reward or punishment can be significant, and
one would wish to arrive at the correct learning conclusion by incurring
minimum cost. In this paper, we present a stochastic approach to reinforcement
learning which explicitly models the variability present in the learning
environment and the cost of observation. Criteria and rules for learning
success are quantitatively analyzed, and probabilities of exceeding the
observation cost bounds are also obtained.Comment: AIKE 201
Quasinormal Modes of Dirty Black Holes
Quasinormal mode (QNM) gravitational radiation from black holes is expected
to be observed in a few years. A perturbative formula is derived for the shifts
in both the real and the imaginary part of the QNM frequencies away from those
of an idealized isolated black hole. The formulation provides a tool for
understanding how the astrophysical environment surrounding a black hole, e.g.,
a massive accretion disk, affects the QNM spectrum of gravitational waves. We
show, in a simple model, that the perturbed QNM spectrum can have interesting
features.Comment: 4 pages. Published in PR
Prescription for experimental determination of the dynamics of a quantum black box
We give an explicit prescription for experimentally determining the evolution
operators which completely describe the dynamics of a quantum mechanical black
box -- an arbitrary open quantum system. We show necessary and sufficient
conditions for this to be possible, and illustrate the general theory by
considering specifically one and two quantum bit systems. These procedures may
be useful in the comparative evaluation of experimental quantum measurement,
communication, and computation systems.Comment: 6 pages, Revtex. Submitted to J. Mod. Op
Unification of bulk and interface electroresistive switching in oxide systems
We demonstrate that the physical mechanism behind electroresistive switching
in oxide Schottky systems is electroformation, as in insulating oxides.
Negative resistance shown by the hysteretic current-voltage curves proves that
impact ionization is at the origin of the switching. Analyses of the
capacitance-voltage and conductance-voltage curves through a simple model show
that an atomic rearrangement is involved in the process. Switching in these
systems is a bulk effect, not strictly confined at the interface but at the
charge space region.Comment: 4 pages, 3 figures, accepted in PR
Financial Crisis and the Comovements of Housing Sub-markets: Do relationships change after a crisis?
This study of the co-movements of the transaction prices and trading volumes reveal that the mean correlation of prices, and trading volumes alike, among different housing sub-markets increases during the market boom. After a financial crisis, the correlations drop dramatically and stay low. The distribution of the correlations changes from skewed to symmetric. All these coincide with the increase in the total variance of prices, as well as the share of the idiosyncratic component in the total variance after the crisis. These findings are consistent to a family of theories which emphasize on “regime switch” in expectation.financial crisis; hedonic pricing; structural break; evolution of valuation; rolling regression
Perturbative Approach to the Quasinormal Modes of Dirty Black Holes
Using a recently developed perturbation theory for uasinormal modes (QNM's),
we evaluate the shifts in the real and imaginary parts of the QNM frequencies
due to a quasi-static perturbation of the black hole spacetime. We show the
perturbed QNM spectrum of a black hole can have interesting features using a
simple model based on the scalar wave equation.Comment: Published in PR
Clinical Toxicologic Studies on Freon R FE 1301
After conducting appropriate animal tests to ascertain safe levels, human subjects were exposed to concentrations of from 1.25% to 16.9% V/V of FE 1301. Assessment of judgement, alertness and neuromuscular skill indicated minimal but discernible effects at the lowest concentration in some individuals. At 10% V/V all subjects were effected. Stage I anesthesia occurred at 15% and Stage II would probably have occurred at 20%. A marked cardiac arrhythmia resulted in one subject exposed to 14%. There was complete recovery in all subjects within 20 minutes after exposure. No liver dysfunction occurred. The critical level for effective fire control is near 6%. This level would be acceptable on clinical toxicologic criteria
Numerical modelling of methane oxidation efficiency and coupled water-gas-heat reactive transfer in a sloping landfill cover
Nanostructuring GaN using microsphere lithography
The authors report on the fabrication and characterization of nanopillar arrays on GaN substrates using the technique of microsphere lithography. Self-assembled hexagonally packed silica microsphere arrays were formed on GaN wafers by spin coating and tilting. By precision control of process parameters, a monolayer can be formed over a wide region. The silica microspheres act as a hard mask for pattern transfer of the nanostructures. After dry etching, arrays of nanopillars were formed on the surface of the wafer. The ordered nanostructures can be clearly seen in the scanning electron microscopy images, while photoluminescence measurements revealed a twofold enhancement of light emission intensity. © 2008 American Vacuum Society.published_or_final_versio
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