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