7,900 research outputs found
Varieties of Quantum Measurement
Quantum measurement theory has fallen under the resticting influence of the
attempt to explain the fundamental axioms of quantum theory in terms of the
theory itself. This has not only led to confusion but has also restricted our
attention to a limited class of measurements. This paper outlines some of the
novel types of measurements which fall outside the usual textbook description.Comment: 14p
Acceleration Radiation for Orbiting Electrons
This paper presents an analysis of the radiation seen by an observer in
circular acceleration, for a magnetic spin. This is applied to an electron in a
storage ring, and the subtilty of the interaction of the spin with the spatial
motion of the electron is explicated. This interaction is shown to be time
dependent (in the radiating frame), which explains the strange results found
for the electron's residual polarisation in the literature. Finally, some brief
comments about the radiation emitted by an accelerating detector are made where
it is shown that the spectrum is correlated in that particles are emitted in
pairs.Comment: 21pp 7fi
Simulatable security for quantum protocols
The notion of simulatable security (reactive simulatability, universal
composability) is a powerful tool for allowing the modular design of
cryptographic protocols (composition of protocols) and showing the security of
a given protocol embedded in a larger one. Recently, these methods have
received much attention in the quantum cryptographic community.
We give a short introduction to simulatable security in general and proceed
by sketching the many different definitional choices together with their
advantages and disadvantages.
Based on the reactive simulatability modelling of Backes, Pfitzmann and
Waidner we then develop a quantum security model. By following the BPW
modelling as closely as possible, we show that composable quantum security
definitions for quantum protocols can strongly profit from their classical
counterparts, since most of the definitional choices in the modelling are
independent of the underlying machine model.
In particular, we give a proof for the simple composition theorem in our
framework.Comment: Added proof of combination lemma; added comparison to the model of
Ben-Or, Mayers; minor correction
Universal approach to gravitational thermal effects
A universal scheme for describing gravitational thermal effects is developed
as a generalization of Unruh effect. Quasi-Rindler (QR) coordinates are
constructed in an arbitrary curved space-time in such a way that the imaginary
QR time be periodical. The observer at rest in QR coordinates should experience
a thermal effect. Application to de Sitter space-time is considered.Comment: 8 pages, LATE
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