8,617 research outputs found
Spin and occupation number entanglement of Dirac fields for non-inertial observers
We investigate the Unruh effect on entanglement taking into account the spin
degree of freedom of the Dirac field. We analyze spin Bell states in this
setting, obtaining their entanglement dependance on the acceleration of one of
the partners. Then, we consider simple analogs to the occupation number
entangled state |00>+|11>, but with spin quantum numbers for |11> showing that,
despite their apparent similitude, while the spinless case is always qubit x
qubit, for the spin case acceleration produces a qubit x qu4it state. We also
introduce a procedure to consistently erase the spin information from our
setting preserving occupation numbers. We show how the maximally entangled
state for occupation number emerges from our setting, we also analyze its
entanglement dependance on acceleration, obtaining a greater entanglement
degradation than in the spinless case.Comment: RevTex, 11 pages, 3 figures. The replacement is due to some minor
misprints correction
Iterated reflection principles over full disquotational truth
Iterated reflection principles have been employed extensively to unfold
epistemic commitments that are incurred by accepting a mathematical theory.
Recently this has been applied to theories of truth. The idea is to start with
a collection of Tarski-biconditionals and arrive by finitely iterated
reflection at strong compositional truth theories. In the context of classical
logic it is incoherent to adopt an initial truth theory in which A and 'A is
true' are inter-derivable. In this article we show how in the context of a
weaker logic, which we call Basic De Morgan Logic, we can coherently start with
such a fully disquotational truth theory and arrive at a strong compositional
truth theory by applying a natural uniform reflection principle a finite number
of times
Variational integrators and time-dependent lagrangian systems
This paper presents a method to construct variational integrators for
time-dependent lagrangian systems. The resulting algorithms are symplectic,
preserve the momentum map associated with a Lie group of symmetries and also
describe the energy variation.Comment: 8 page
Hypatia's silence. Truth, justification, and entitlement.
Hartry Field distinguished two concepts of type-free truth: scientific truth and disquotational truth. We argue that scientific type-free truth cannot do justificatory work in the foundations of mathematics. We also present an argument, based on Crispin Wright's theory of cognitive projects and entitlement, that disquotational truth can do justificatory work in the foundations of mathematics. The price to pay for this is that the concept of disquotational truth requires non-classical logical treatment
The fate of non-trivial entanglement under gravitational collapse
We analyse the evolution of the entanglement of a non-trivial initial quantum
field state (which, for simplicity, has been taken to be a bipartite state made
out of vacuum and the first excited state) when it undergoes a gravitational
collapse. We carry out this analysis by generalising the tools developed to
study entanglement behaviour in stationary scenarios and making them suitable
to deal with dynamical spacetimes. We also discuss what kind of problems can be
tackled using the formalism spelled out here as well as single out future
avenues of research.Comment: 9 pages, 2 figures. v2: Added Journal reference and small changes to
match published versio
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