1,486 research outputs found
An Analysis of Air Mobility Express Requirements Operating Within a Lean Logistics Wartime Environment
Lean Logistics was developed in response to budget cuts, force reductions, and a new political world order. The primary objective of Lean Logistics is to minimize the total system wide costs of the Air Force organization. Currently, the Air Force is seeking to cut costs by reducing inventories, improving repair processes, and employing faster transportation where possible. The purpose of this thesis is to determine if the Air Mobility Express (AMX) current sizing plan is capable of supporting the retrograde assets generated during the sustainment portion of a war. The Dyna-METRIC version 6.4 simulation program is employed to analyze the effect of varying such parameters as flying hours and retrograde shipment time on the weight and space required to move retrograde assets. Analysis of the results was accomplished using a Small Sample Test of Hypothesis. The results indicated that the current sizing plan is capable of handling the retrograde cargo generated by four F-16C squadrons for the six scenarios evaluated. This research also hints that while the current plan is capable of supporting four F-16C squadrons, it should be increased to support the transportation of reparables for all weapon systems involved in the war effort
Efficient engineering of multi-atom entanglement through single-photon detections
We propose an efficient scheme to engineer multi-atom entanglement by
detecting cavity decay through single-photon detectors. In the special case of
two atoms, this scheme is much more efficient than previous probabilistic
schemes, and insensitive to randomness in the atom's position. More generally,
the scheme can be used to prepare arbitrary superpositions of multi-atom Dicke
states without the requirements of high-efficiency detection and separate
addressing of different atoms.Comment: 5 pages, 2 figure
Optimal Quantum Clocks
A quantum clock must satisfy two basic constraints. The first is a bound on
the time resolution of the clock given by the difference between its maximum
and minimum energy eigenvalues. The second follows from Holevo's bound on how
much classical information can be encoded in a quantum system. We show that
asymptotically, as the dimension of the Hilbert space of the clock tends to
infinity, both constraints can be satisfied simultaneously. The experimental
realization of such an optimal quantum clock using trapped ions is discussed.Comment: 4 pages, revtex, 1 figure, revision contains some new result
Symmetry and Temperature dependence of the Order parameter in MgB2 from point contact measurements
We have performed differential conductance versus voltage measurements of
Au/MgB2 point contacts. We find that the dominant component in the conductance
is due to Andreev reflection. The results are fitted to the theoretical model
of BTK for an s-wave symmetry from which we extract the value of the order
parameter (Delta) and its temperature dependence. From our results we also
obtain a lower experimental bound on the Fermi velocity in MgB2.Comment: 7 pages (Including figure captions) and 4 figure
Entangling many atomic ensembles through laser manipulation
We propose an experimentally feasible scheme to generate
Greenberger-Horne-Zeilinger (GHZ) type of maximal entanglement between many
atomic ensembles based on laser manipulation and single-photon detection. The
scheme, with inherent fault tolerance to the dominant noise and efficient
scaling of the efficiency with the number of ensembles, allows to maximally
entangle many atomic ensemble within the reach of current technology. Such a
maximum entanglement of many ensembles has wide applications in demonstration
of quantum nonlocality, high-precision spectroscopy, and quantum information
processing.Comment: 4 pages, 1 figur
States for phase estimation in quantum interferometry
Ramsey interferometry allows the estimation of the phase of rotation
of the pseudospin vector of an ensemble of two-state quantum systems. For
small, the noise-to-signal ratio scales as the spin-squeezing parameter
, with possible for an entangled ensemble. However states with
minimum are not optimal for single-shot measurements of an arbitrary
phase. We define a phase-squeezing parameter, , which is an appropriate
figure-of-merit for this case. We show that (unlike the states that minimize
), the states that minimize can be created by evolving an
unentangled state (coherent spin state) by the well-known 2-axis
counter-twisting Hamiltonian. We analyse these and other states (for example
the maximally entangled state, analogous to the optical "NOON" state ) using several different properties, including ,
, the coefficients in the pseudo angular momentum basis (in the three
primary directions) and the angular Wigner function . Finally
we discuss the experimental options for creating phase squeezed states and
doing single-shot phase estimation.Comment: 8 pages and 5 figure
Even-odd parity effects in conductance and shot noise of metal-atomic wire-metal(superconducting) junctions
In this paper, we study the conductance and shot noise in transport through a
multi-site system in a two terminal configuration. The dependence of the
transport on the number of atoms in the atomic wire is investigated using a
tight-binding Hamiltonian and the nonequilibrium Green's function method. In
addition to reproducing the even-odd behavior in the transmission probability
at the Fermi energy or the linear response conductance in the normal-atomic
wire-normal metallic(NAN) junctions, we find the following: (i) The shot noise
is larger in the even-numbered atomic wire than in the odd-numbered wire. (ii)
The Andreev conductance displays the same even-odd parity effects in the
normal-atomic wire-superconducting(NAS) junctions. In general, the conductance
is higher in the odd-numbered atomic wire than in the even-numbered wire. When
the number of sites () is odd and the atomic wire is mirror symmetric with
respect to the center of the atomic wire, the conductance does not depend on
the details of the hopping matrices in the atomic wire, but is solely
determined by the coupling strength to the two leads. When is even, the
conductance is sensitive to the values of the hopping matrices.Comment: 12 pages, 9 figure
Many-particle entanglement with Bose--Einstein condensates
We propose a method to produce entangled states of several particles starting
from a Bose-Einstein condensate. In the proposal, a single fast pulse
is applied to the atoms and due to the collisional interaction, the subsequent
free time evolution creates an entangled state involving all atoms in the
condensate. The created entangled state is a spin-squeezed state which could be
used to improve the sensitivity of atomic clocks.Comment: 4 pages. Minor modification
Stabilizing single atom contacts by molecular bridge formation
Gold-molecule-gold junctions can be formed by carefully breaking a gold wire
in a solution containing dithiolated molecules. Surprisingly, there is little
understanding on the mechanical details of the bridge formation process and
specifically on the role that the dithiol molecules play themselves. We propose
that alkanedithiol molecules have already formed bridges between the gold
electrodes before the atomic gold-gold junction is broken. This leads to
stabilization of the single atomic gold junction, as observed experimentally.
Our data can be understood within a simple spring model.Comment: 14 pages, 3 figures, 1 tabl
Lives Saved Tool (LiST) costing: a module to examine costs and prioritize interventions
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