169,756 research outputs found
Fully automatic telemetry data processor
Satellite Telemetry Automatic Reduction System /STARS 2/, a fully automatic computer-controlled telemetry data processor, maximizes data recovery, reduces turnaround time, increases flexibility, and improves operational efficiency. The system incorporates a CDC 3200 computer as its central element
Formalization of the fundamental group in untyped set theory using auto2
We present a new framework for formalizing mathematics in untyped set theory
using auto2. Using this framework, we formalize in Isabelle/FOL the entire
chain of development from the axioms of set theory to the definition of the
fundamental group for an arbitrary topological space. The auto2 prover is used
as the sole automation tool, and enables succinct proof scripts throughout the
project.Comment: 17 pages, accepted for ITP 201
Boundary correlation function of fixed-to-free bcc operators in square-lattice Ising model
We calculate the boundary correlation function of fixed-to-free boundary
condition changing operators in the square-lattice Ising model. The correlation
function is expressed in four different ways using block Toeplitz
determinants. We show that these can be transformed into a scalar Toeplitz
determinant when the size of the matrix is even. To know the asymptotic
behavior of the correlation function at large distance we calculate the
asymptotic behavior of this scalar Toeplitz determinant using the Szeg\"o's
theorem and the Fisher-Hartwig theorem. At the critical temperature we confirm
the power-law behavior of the correlation function predicted by conformal field
theory
Minimax optimization of entanglement witness operator for the quantification of three-qubit mixed-state entanglement
We develop a numerical approach for quantifying entanglement in mixed quantum
states by convex-roof entanglement measures, based on the optimal entanglement
witness operator and the minimax optimization method. Our approach is
applicable to general entanglement measures and states and is an efficient
alternative to the conventional approach based on the optimal pure-state
decomposition. Compared with the conventional one, it has two important merits:
(i) that the global optimality of the solution is quantitatively verifiable,
and (ii) that the optimization is considerably simplified by exploiting the
common symmetry of the target state and measure. To demonstrate the merits, we
quantify Greenberger-Horne-Zeilinger (GHZ) entanglement in a class of
three-qubit full-rank mixed states composed of the GHZ state, the W state, and
the white noise, the simplest mixtures of states with different genuine
multipartite entanglement, which have not been quantified before this work. We
discuss some general properties of the form of the optimal witness operator and
of the convex structure of mixed states, which are related to the symmetry and
the rank of states
Relation Between Quantum Speed Limits And Metrics On U(n)
Recently, Chau [Quant. Inform. & Comp. 11, 721 (2011)] found a family of
metrics and pseudo-metrics on -dimensional unitary operators that can be
interpreted as the minimum resources (given by certain tight quantum speed
limit bounds) needed to transform one unitary operator to another. This result
is closely related to the weighted -norm on . Here we
generalize this finding by showing that every weighted -norm on
with 1\le p \le \limitingp induces a metric and a
pseudo-metric on -dimensional unitary operators with quantum
information-theoretic meanings related to certain tight quantum speed limit
bounds. Besides, we investigate how far the correspondence between the
existence of metrics and pseudo-metrics of this type and the quantum speed
limits can go.Comment: minor amendments, 6 pages, to appear in J.Phys.
Theory for Gossamer and Resonating Valence Bond Superconductivity
We use an effective Hamiltonian for two-dimensional Hubbard model including
an antiferromagnetic spin-spin coupling term to study recently proposed
gossamer superconductivity. We formulate a renormalized mean field theory to
approximately take into account the strong correlation effect in the partially
projected Gutzwiller wavefucntions. At the half filled, there is a first order
phase transition to separate a Mott insulator at large Coulomb repulsion U from
a gossamer superconductor at small U. Away from the half filled,the Mott
insulator is evolved into an resonating valence bond state, which is
adiabatically connected to the gossamer superconductor.Comment: 10 pages, 13 figure
The jet and the disk of the HH 212 low-mass protostar imaged by ALMA: SO and SO2 emission
To investigate the disk formation and jet launch in protostars is crucial to
comprehend the earliest stages of star and planet formation. We aim to
constrain the properties of the molecular jet and the disk of the HH 212
protostellar system at unprecedented angular scales through ALMA observations
of sulfur-bearing molecules, SO 9(8)-8(7), SO 10(11)-10(10), SO2 8(2,6)-7(1,7).
SO 9(8)-8(7) and SO2 8(2,6)-7(1,7) show broad velocity profiles. At systemic
velocity they probe the circumstellar gas and the cavity walls. Going from low
to high blue-/red-shifted velocities the emission traces the wide-angle outflow
and the fast (~100-200 km/s) and collimated (~90 AU) molecular jet revealing
the inner knots with timescales <50 years. The jet transports a mass loss rate
>0.2-2e-6 Msun/yr, implying high ejection efficiency (>0.03-0.3). The SO and
SO2 abundances in the jet are ~1e-7-1e-6. SO 10(11)-10(10) emission is compact
and shows small-scale velocity gradients indicating that it originates partly
from the rotating disk previously seen in HCO+ and C17O, and partly from the
base of the jet. The disk mass is >0.002-0.013 Msun, and the SO abundance in
the disk is ~1e-8-1e-7. SO and SO2 are effective tracers of the molecular jet
in the inner few hundreds AU from the protostar. Their abundances indicate that
1% - 40% of sulfur is in SO and SO2 due to shocks in the jet/outflow and/or to
ambipolar diffusion at the wind base. The SO abundance in the disk is 3-4
orders of magnitude larger than in evolved protoplanetary disks. This may be
due to an SO enhancement in the accretion shock at the envelope-disk interface
or in spiral shocks if the disk is partly gravitationally unstable.Comment: 13 pages, 10 figures, accepted for publication by A&
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