Strong subadditivity of von Neumann entropy, proved in 1973 by Lieb and Ruskai, is a cornerstone of quantum coding theory. All other known inequalities for entropies of quantum systems may be derived… (More)

We discuss the use of histories labelled by a continuous time in the approach to consistenthistories quantum theory in which propositions about the history of the system are represented by projection… (More)

In standard quantum theory, the ideas of information-entropy and of pure states are closely linked. States are represented by density matrices ρ on a Hilbert space and the information-entropy −tr(ρ… (More)

We describe how inequivalent quantizations (superselection sectors) arise within two related algebraic approaches to quantum mechanics (viz. quantization by canonical groups and by C*-algebras). By… (More)

If NMR systems are to be used as practical quantum computers, the number of coupled spins will need to be so large that it is not feasible to rely on purely heteronuclear spin systems. The… (More)

The Greenberger ± Horne ± Zeilinger state is the most famous example of a state with multiparticle entanglement . In this article we describe a group theoretic framework we have been developing for… (More)

A complete, straightforward and natural Lagrangian description is given for the classical non-relativistic dynamics of a particle with colour or internal symmetry degrees of freedom moving in a… (More)

The relative entropy of two distributions of n random variables, and more generally of two n-party quantum states, is an important quantity exhibiting, for example, the extent to which the two… (More)

We show how to construct path integrals for quantum mechanical systems where the space of configurations is a general non-compact symmetric space. Associated with this path integral is a perturbation… (More)