Triviality of Entanglement Entropy in the Galilean Vacuum

We study the entanglement entropy of the vacuum in non-relativistic local theories with Galilean or Schr\"{o}dinger symmetry. We clear some confusion in the literature on the free Schr\"odinger case. We find that with only positive $U(1)$ charge particles (states) and a unique zero $U(1)$ charge state (the vacuum) the entanglement entropy must vanish in that state

Redeeming Bad Theories

We give a Seiberg-like dual description of the interacting superconformal infrared fixed point of $\mathcal{N}=4$ gauge theory in three dimensions with vanishing Chern Simons level and $N_c\le N_f<2N_c$ fundamental flavors. These theories are known as "bad" theories due to the existence of unitarity violating monopole operators. We show that, in a dual description, all such operators are realized by free fields and the remainder theory is the Seiberg-like dual previously identified using the type IIB brane construction

Quantum mechanics as a theory of probability

We develop and defend the thesis that the Hilbert space formalism of quantum mechanics is a new theory of probability. The theory, like its classical counterpart, consists of an algebra of events, and the probability measures defined on it. The construction proceeds in the following steps: (a) Axioms for the algebra of events are introduced following Birkhoff and von Neumann. All axioms, except the one that expresses the uncertainty principle, are shared with the classical event space. The only models for the set of axioms are lattices of subspaces of inner product spaces over a field K. (b) Another axiom due to Soler forces K to be the field of real, or complex numbers, or the quaternions. We suggest a probabilistic reading of Soler's axiom. (c) Gleason's theorem fully characterizes the probability measures on the algebra of events, so that Born's rule is derived. (d) Gleason's theorem is equivalent to the existence of a certain finite set of rays, with a particular orthogonality graph (Wondergraph). Consequently, all aspects of quantum probability can be derived from rational probability assignments to finite "quantum gambles". We apply the approach to the analysis of entanglement, Bell inequalities, and the quantum theory of macroscopic objects. We also discuss the relation of the present approach to quantum logic, realism and truth, and the measurement problem.Comment: 37 pages, 3 figures. Forthcoming in a Festschrift for Jeffrey Bub, ed. W. Demopoulos and the author, Springer (Kluwer): University of Western Ontario Series in Philosophy of Scienc

'How to feel safe': international students study migration

A variety of institutional and representational mechanisms are used in the construction of 'international students' and other 'migrants' or 'ethnic minorities' as two distinctive social categories. As part of these construction processes, the individuals affiliated with each group are located in different positions within the matrix of social power relations: they are granted with differential abilities to exercise their right to freedom of movement, and play different roles in the process of knowledge production. This article will explore how these processes occur in a specific context, through an autoethnographic account of the experiences of the author as an international student at the University of Amsterdam. This account suggests a thematic and methodological alternative to the safe position that the academic training as prospective migration scholars offers to students