23,187 research outputs found
Real-time and Probabilistic Temporal Logics: An Overview
Over the last two decades, there has been an extensive study on logical
formalisms for specifying and verifying real-time systems. Temporal logics have
been an important research subject within this direction. Although numerous
logics have been introduced for the formal specification of real-time and
complex systems, an up to date comprehensive analysis of these logics does not
exist in the literature. In this paper we analyse real-time and probabilistic
temporal logics which have been widely used in this field. We extrapolate the
notions of decidability, axiomatizability, expressiveness, model checking, etc.
for each logic analysed. We also provide a comparison of features of the
temporal logics discussed
Design of multimedia processor based on metric computation
Media-processing applications, such as signal processing, 2D and 3D graphics
rendering, and image compression, are the dominant workloads in many embedded
systems today. The real-time constraints of those media applications have
taxing demands on today's processor performances with low cost, low power and
reduced design delay. To satisfy those challenges, a fast and efficient
strategy consists in upgrading a low cost general purpose processor core. This
approach is based on the personalization of a general RISC processor core
according the target multimedia application requirements. Thus, if the extra
cost is justified, the general purpose processor GPP core can be enforced with
instruction level coprocessors, coarse grain dedicated hardware, ad hoc
memories or new GPP cores. In this way the final design solution is tailored to
the application requirements. The proposed approach is based on three main
steps: the first one is the analysis of the targeted application using
efficient metrics. The second step is the selection of the appropriate
architecture template according to the first step results and recommendations.
The third step is the architecture generation. This approach is experimented
using various image and video algorithms showing its feasibility
10-qubit entanglement and parallel logic operations with a superconducting circuit
Here we report on the production and tomography of genuinely entangled
Greenberger-Horne-Zeilinger states with up to 10 qubits connecting to a bus
resonator in a superconducting circuit, where the resonator-mediated
qubit-qubit interactions are used to controllably entangle multiple qubits and
to operate on different pairs of qubits in parallel. The resulting 10-qubit
density matrix is unambiguously probed, with a fidelity of .
Our results demonstrate the largest entanglement created so far in solid-state
architectures, and pave the way to large-scale quantum computation.Comment: Revised version with 16 pages, 13 figures, and 2 table
Classical Vs Quantum Probability in Sequential Measurements
We demonstrate in this paper that the probabilities for sequential
measurements have features very different from those of single-time
measurements. First, they cannot be modelled by a classical stochastic process.
Second, they are contextual, namely they depend strongly on the specific
measurement scheme through which they are determined. We construct
Positive-Operator-Valued measures (POVM) that provide such probabilities. For
observables with continuous spectrum, the constructed POVMs depend strongly on
the resolution of the measurement device, a conclusion that persists even if we
consider a quantum mechanical measurement device or the presence of an
environment. We then examine the same issues in alternative interpretations of
quantum theory. We first show that multi-time probabilities cannot be naturally
defined in terms of a frequency operator. We next prove that local hidden
variable theories cannot reproduce the predictions of quantum theory for
sequential measurements, even when the degrees of freedom of the measuring
apparatus are taken into account. Bohmian mechanics, however, does not fall in
this category. We finally examine an alternative proposal that sequential
measurements can be modelled by a process that does not satisfy the Kolmogorov
axioms of probability. This removes contextuality without introducing
non-locality, but implies that the empirical probabilities cannot be always
defined (the event frequencies do not converge). We argue that the predictions
of this hypothesis are not ruled out by existing experimental results
(examining in particular the "which way" experiments); they are, however,
distinguishable in principle.Comment: 56 pages, latex; revised and restructured. Version to appear in
Found. Phy
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