308 research outputs found
Yangian symmetry of scattering amplitudes in N=4 super Yang-Mills theory
Tree-level scattering amplitudes in N=4 super Yang-Mills theory have recently
been shown to transform covariantly with respect to a 'dual' superconformal
symmetry algebra, thus extending the conventional superconformal symmetry
algebra psu(2,2|4) of the theory. In this paper we derive the action of the
dual superconformal generators in on-shell superspace and extend the dual
generators suitably to leave scattering amplitudes invariant. We then study the
algebra of standard and dual symmetry generators and show that the inclusion of
the dual superconformal generators lifts the psu(2,2|4) symmetry algebra to a
Yangian. The non-local Yangian generators acting on amplitudes turn out to be
cyclically invariant due to special properties of psu(2,2|4). The
representation of the Yangian generators takes the same form as in the case of
local operators, suggesting that the Yangian symmetry is an intrinsic property
of planar N=4 super Yang-Mills, at least at tree level.Comment: 23 pages, no figures; v2: typos corrected, references added; v3:
minor changes, references adde
Quantum correlated twin atomic beams via photo-dissociation of a molecular Bose-Einstein condensate
We study the process of photo-dissociation of a molecular Bose-Einstein
condensate as a potential source of strongly correlated twin atomic beams. We
show that the two beams can possess nearly perfect quantum squeezing in their
relative numbers.Comment: Corrected LaTeX file layou
The Classical Exchange Algebra of AdS5 x S5 String Theory
The classical exchange algebra satisfied by the monodromy matrix of AdS5 x S5
string theory in the Green-Schwarz formulation is determined by using a
first-order Hamiltonian formulation and by adding to the Bena-Polchinski-Roiban
Lax connection terms proportional to constraints. This enables in particular to
show that the conserved charges of this theory are in involution. This result
is obtained for a general world-sheet metric. The same exchange algebra is
obtained within the pure spinor description of AdS5 x S5 string theory. These
results are compared to the one obtained by A. Mikhailov and S. Schaefer-Nameki
for the pure spinor formulation.Comment: 37 pages; v2: Result on Jacobi identity and Yang-Baxter equation
added in section 3.3; v3: References added; v4: Comparison with ref [12]
clarified in section 3.
Scattering in Mass-Deformed N>=4 Chern-Simons Models
We investigate the scattering matrix in mass-deformed N>=4 Chern-Simons
models including as special cases the BLG and ABJM theories of multiple M2
branes. Curiously the structure of this scattering matrix in three spacetime
dimensions is equivalent to (a) the two-dimensional worldsheet matrix found in
the context of AdS/CFT integrability and (b) the R-matrix of the
one-dimensional Hubbard model. The underlying reason is that all three models
are based on an extension of the psu(2|2) superalgebra which constrains the
matrix completely. We also compute scattering amplitudes in one-loop field
theory and find perfect agreement with scattering unitarity.Comment: 63 pages, v2: minor corrections, v3: minor improvement
Entanglement of two-mode Bose-Einstein condensates
We investigate the entaglement characteristics of two general bimodal
Bose-Einstein condensates - a pair of tunnel-coupled Bose-Einstein condensates
and the atom-molecule Bose-Einstein condensate. We argue that the entanglement
is only physically meaningful if the system is viewed as a bipartite system,
where the subsystems are the two modes. The indistinguishibility of the
particles in the condensate means that the atomic constituents are physically
inaccessible and thus the degree of entanglement between individual particles,
unlike the entanglement between the modes, is not experimentally relevant so
long as the particles remain in the condensed state. We calculate the
entanglement between the modes for the exact ground state of the two bimodal
condensates and consider the dynamics of the entanglement in the tunnel-coupled
case.Comment: 11 pages, 8 figures, submitted to Physical Review A, to be presented
at the third UQ Mathematical Physics workshop, Oct. 4-6; changes made in
response to referee comment
Quantum-noise-induced macroscopic revivals in second-harmonic generation
We investigate the behavior of the fundamental and second-harmonic fields in phase-matched traveling plane-wave second-harmonic generation, using the full-operator equations of motion. We find that, after a certain interaction length, both the macroscopic and quantum-statistical properties of the harmonic and fundamental fields are qualitatively different from those found in previous analyses. The mean fields do not vary in a monotonic way, but oscillate with the propagation length, leading to an unexpected periodic revival of the fundamental field, triggered by the quantum fluctuations always present in the mode. Accordingly, the amplitude noise of the fundamental, previously predicted to be perfectly squeezed for long interaction lengths, actually reaches a very small minimum for a definite length, then increases again
Soliton back-action evading measurement using spectral filtering
We report on a back-action evading (BAE) measurement of the photon number of
fiber optical solitons operating in the quantum regime. We employ a novel
detection scheme based on spectral filtering of colliding optical solitons. The
measurements of the BAE criteria demonstrate significant quantum state
preparation and transfer of the input signal to the signal and probe outputs
exiting the apparatus, displaying the quantum-nondemolition (QND) behavior of
the experiment.Comment: 5 pages, 5 figure
Role of quantum statistics in the photoassociation of Bose-Einstein condensates
We show that the photoassociation of an atomic Bose-Einstein condensate to form condensed molecules is a chemical process which not only does not obey the Arrhenius rules for chemical reactions, but that it can also depend on the quantum statistics of the reactants. Comparing the predictions of a truncated Wigner representation for different initial quantum states, we find that, even when the quantum prediction for an initial coherent state is close to the Gross-Pitaevskii prediction, other quantum states may result in very different dynamics
Effectiveness evaluation of data mining based IDS
Proceeding of: 6th Industrial Conference on Data Mining, ICDM 2006, Leipzig, Germany, July 14-15, 2006.Data mining has been widely applied to the problem of Intrusion Detection in computer networks. However, the misconception of the underlying problem has led to out of context results. This paper shows that factors such as the probability of intrusion and the costs of responding to detected intrusions must be taken into account in order to compare the effectiveness of machine learning algorithms over the intrusion detection domain. Furthermore, we show the advantages of combining different detection techniques. Results regarding the well known 1999 KDD dataset are shown.Publicad
On T-Duality and Integrability for Strings on AdS Backgrounds
We discuss an interplay between T-duality and integrability for certain
classical non-linear sigma models. In particular, we consider strings on the
AdS_5 x S^5 background and perform T-duality along the four isometry directions
of AdS_5 in the Poincare patch. The T-dual of the AdS_5 sigma model is again a
sigma model on an AdS_5 space. This classical T-duality relation was used in
the recently uncovered connection between light-like Wilson loops and MHV gluon
scattering amplitudes in the strong coupling limit of the AdS/CFT duality. We
show that the explicit coordinate dependence along the T-duality directions of
the associated Lax connection (flat current) can be eliminated by means of a
field dependent gauge transformation. As a result, the gauge equivalent Lax
connection can easily be T-dualized, i.e. written in terms of the dual set of
isometric coordinates. The T-dual Lax connection can be used for the derivation
of infinitely many conserved charges in the T-dual model. Our construction
implies that local (Noether) charges of the original model are mapped to
non-local charges of the T-dual model and vice versa.Comment: 20 pages; v2: misprints corrected, references and minor
clarifications adde
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