2,491 research outputs found
Experimental evidence of a {\phi} Josephson junction
We demonstrate experimentally the existence of Josephson junctions having a
doubly degenerate ground state with an average Josephson phase \psi=\pm{\phi}.
The value of {\phi} can be chosen by design in the interval 0<{\phi}<\pi. The
junctions used in our experiments are fabricated as 0-{\pi} Josephson junctions
of moderate normalized length with asymmetric 0 and {\pi} regions. We show that
(a) these {\phi} Josephson junctions have two critical currents, corresponding
to the escape of the phase {\psi} from -{\phi} and +{\phi} states; (b) the
phase {\psi} can be set to a particular state by tuning an external magnetic
field or (c) by using a proper bias current sweep sequence. The experimental
observations are in agreement with previous theoretical predictions
Singular projective varieties and quantization
By the quantization condition compact quantizable Kaehler manifolds can be
embedded into projective space. In this way they become projective varieties.
The quantum Hilbert space of the Berezin-Toeplitz quantization (and of the
geometric quantization) is the projective coordinate ring of the embedded
manifold. This allows for generalization to the case of singular varieties. The
set-up is explained in the first part of the contribution. The second part of
the contribution is of tutorial nature. Necessary notions, concepts, and
results of algebraic geometry appearing in this approach to quantization are
explained. In particular, the notions of projective varieties, embeddings,
singularities, and quotients appearing in geometric invariant theory are
recalled.Comment: 21 pages, 3 figure
The Invisible Thin Red Line
The aim of this paper is to argue that the adoption of an unrestricted principle of bivalence is compatible with a metaphysics that (i) denies that the future is real, (ii) adopts nomological indeterminism, and (iii) exploits a branching structure to provide a semantics for future contingent claims. To this end, we elaborate what we call Flow Fragmentalism, a view inspired by Kit Fine (2005)’s non-standard tense realism, according to which reality is divided up into maximally coherent collections of tensed facts. In this way, we show how to reconcile a genuinely A-theoretic branching-time model with the idea that there is a branch corresponding to the thin red line, that is, the branch that will turn out to be the actual future history of the world
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