The goal of defining localized quanta and their localization properties in quantum field theory has generated a large debate ultimately leading to the far reaching question of whether QFT describes particles or not. The sharpest criteria for localization is that any state that is strictly localized within some region V of space should produce the same expectation value as the vacuum state for any local operator O(x) with x outside V. Actually, it is impossible to construct such localized states using Fock states with any finite number of particles. Hence, the Fock states of QFT cannot be taken to represent particle states if we want them to be localized within some region of space. In this talk we start from the existence of inequivalent representations of the algebra of observables in field theory to construct particle states satisfying localization properties and interpret them in terms of the standard Fock space states.

Meeting on Relativistic Quantum Walks, Université de Grenoble, France, February 6,7 2014. Presentación en Power Point de 22 diapositivas.

Peer Reviewed