31,780 research outputs found
Quantum spin circulator in Y junctions of Heisenberg chains
We show that a quantum spin circulator, a nonreciprocal device that routes
spin currents without any charge transport, can be achieved in Y junctions of
identical spin- Heisenberg chains coupled by a chiral three-spin
interaction. Using bosonization, boundary conformal field theory, and
density-matrix renormalization group simulations, we find that a chiral fixed
point with maximally asymmetric spin conductance arises at a critical point
separating a regime of disconnected chains from a spin-only version of the
three-channel Kondo effect. We argue that networks of spin-chain Y junctions
provide a controllable approach to construct long-sought chiral spin liquid
phases.Comment: 9 pages, 3 figure
Bayesian Analysis of Simple Random Densities
A tractable nonparametric prior over densities is introduced which is closed
under sampling and exhibits proper posterior asymptotics.Comment: 19 pages; 6 figure
Predictive analysis of microarray data
Microarray gene expression data are analyzed by means of a Bayesian
nonparametric model, with emphasis on prediction of future observables,
yielding a method for selection of differentially expressed genes and a
classifier
Influence of chirping the Raman lasers in an atom gravimeter: phase shifts due to the Raman light shift and to the finite speed of light
We present here an analysis of the influence of the frequency dependence of
the Raman laser light shifts on the phase of a Raman-type atom gravimeter.
Frequency chirps are applied to the Raman lasers in order to compensate gravity
and ensure the resonance of the Raman pulses during the interferometer. We show
that the change in the Raman light shift when this chirp is applied only to one
of the two Raman lasers is enough to bias the gravity measurement by a fraction
of Gal (Gal~=~~m/s). We also show that this effect is
not compensated when averaging over the two directions of the Raman wavevector
. This thus constitutes a limit to the rejection efficiency of the
-reversal technique. Our analysis allows us to separate this effect from the
effect of the finite speed of light, which we find in perfect agreement with
expected values. This study highlights the benefit of chirping symmetrically
the two Raman lasers
Angular Momentum of the BTZ Black Hole in the Teleparallel Geometry
We carry out the Hamiltonian formulation of the three- dimensional
gravitational teleparallelism without imposing the time gauge condition, by
rigorously performing the Legendre transform. Definition of the gravitational
angular momentum arises by suitably interpreting the integral form of the
constraint equation Gama^ik=0 as an angular momentum equation. The
gravitational angular momentum is evaluated for the gravitational field of a
rotating BTZ black hole.Comment: 17 pages, no figures, v2: some misprints corrected, Ref.s added, Eq.s
revised, submitted to General Relativity and Gravitatio
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