5,577 research outputs found
Quantum Vorticity at positive temperature for spin systems with continuous symmetry
We propose a definition of vorticity at inverse temperature for Gibbs
states in quantum XY or Heisenberg spin systems on the lattice by testing
on a complete set of observables ("one-point functions").
Imposing a compression of Pauli matrices at the boudary, which stands for the
classical environment, we perform some numerical simulations on finite lattices
in case of XY model, which exhibit usual vortex patterns.Comment: ISQS24, Institute of Physics, Prague, 201
Quantum vorticity at thermal equilibrium for spins systems with continuous symmetry
We propose a definition of vorticity at inverse temperature \beta for Gibbs
states in quantum XY spin systems on the lattice by testing \exp[-\beta H] on a
complete set of observables ("one-point functions"). We show in particular that
it is independent of the choice of a particular basis. Imposing a compression
of Pauli matrices at the boudary, which stands for the classical environment,
we make some numerical simulations on finite lattices, and exhibit usual vortex
patterns.Comment: 4 figure
Nested Semantics over Finite Trees are Equationally Hard
This paper studies nested simulation and nested trace semantics over the language BCCSP, a basic formalism to express finite process behaviour. It is shown that none of these semantics affords finite (in)equational axiomatizations over BCCSP. In particular, for each of the nested semantics studied in this paper, the collection of sound, closed (in)equations over a singleton action set is not finitely based
K-theory and topological cyclic homology of henselian pairs
Given a henselian pair of commutative rings, we show that the
relative -theory and relative topological cyclic homology with finite
coefficients are identified via the cyclotomic trace . This
yields a generalization of the classical Gabber-Gillet-Thomason-Suslin rigidity
theorem (for mod coefficients, with invertible in ) and McCarthy's
theorem on relative -theory (when is nilpotent).
We deduce that the cyclotomic trace is an equivalence in large degrees
between -adic -theory and topological cyclic homology for a large class
of -adic rings. In addition, we show that -theory with finite
coefficients satisfies continuity for complete noetherian rings which are
-finite modulo . Our main new ingredient is a basic finiteness property
of with finite coefficients.Comment: 59 pages, revised and final versio
Entropy and Quantum Kolmogorov Complexity: A Quantum Brudno's Theorem
In classical information theory, entropy rate and Kolmogorov complexity per
symbol are related by a theorem of Brudno. In this paper, we prove a quantum
version of this theorem, connecting the von Neumann entropy rate and two
notions of quantum Kolmogorov complexity, both based on the shortest qubit
descriptions of qubit strings that, run by a universal quantum Turing machine,
reproduce them as outputs.Comment: 26 pages, no figures. Reference to publication added: published in
the Communications in Mathematical Physics
(http://www.springerlink.com/content/1432-0916/
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