Notes on coarse grainings and functions of observables

Using the Naimark dilation theory we investigate the question under what conditions an observable which is a coarse graining of another observable is a function of it. To this end, conditions for the separability and for the Boolean structure of an observable are given

Capacities and 1-strict subsets in metric spaces

In a complete metric space that is equipped with a doubling measure and supports a Poincar\'e inequality, we study strict subsets, i.e. sets whose variational capacity with respect to a larger reference set is finite, in the case $p=1$. Relying on the concept of fine topology, we give a characterization of those strict subsets that are also sets of finite perimeter, and then we apply this to the study of condensers as well as BV capacities. We also apply the theory to prove a pointwise approximation result for functions of bounded variation.Comment: arXiv admin note: text overlap with arXiv:1812.1108

A computer program for evaluating propellant heating and radiation dosage to crews of nuclear-powered rocket vehicles

Program evaluates propellant heating in a nuclear rocket stage. Program code employs infinite-medium buildup factors to calculate gamma dosage and employs the Albert-Welton kernal to calculate the fast neutron dosage

A note on the measurement of phase space observables with an eight-port homodyne detector

It is well known that the Husimi Q-function of the signal field can actually be measured by the eight-port homodyne detection technique, provided that the reference beam (used for homodyne detection) is a very strong coherent field so that it can be treated classically. Using recent rigorous results on the quantum theory of homodyne detection observables, we show that any phase space observable, and not only the Q-function, can be obtained as a high amplitude limit of the signal observable actually measured by an eight-port homodyne detector. The proof of this fact does not involve any classicality assumption.Comment: 8 pages, 1 figur

An axiomatic basis for quantum mechanics

In this paper we use the framework of generalized probabilistic theories to present two sets of basic assumptions, called axioms, for which we show that they lead to the Hilbert space formulation of quantum mechanics. The key results in this derivation are the co-ordinatization of generalized geometries and a theorem of Sol\'er which characterizes Hilbert spaces among the orthomodular spaces. A generalized Wigner theorem is applied to reduce some of the assumptions of the theorem of Sol\'er to the theory of symmetry in quantum mechanics. Since this reduction is only partial we also point out the remaining open questions.Comment: 39 page

Multigroup calculations of resonance neutron capture in a thick slab of depleted uranium

Multigroup calculations of resonance neutron capture in thick slab of depleted U-23

Covariant localizations in the torus and the phase observables

We describe all the localization observables of a quantum particle in a one-dimensional box in terms of sequences of unit vectors in a Hilbert space. An alternative representation in terms of positive semidefinite complex matrices is furnished and the commutative localizations are singled out. As a consequence, we also get a vector sequence characterization of the covariant phase observables.Comment: 16 pages, no figure, Latex2