7,776 research outputs found
Quantum Communication Through an Unmodulated Spin Chain
We propose a scheme for using an unmodulated and unmeasured spin-chain as a
channel for short distance quantum communications. The state to be transmitted
is placed on one spin of the chain and received later on a distant spin with
some fidelity. We first obtain simple expressions for the fidelity of quantum
state transfer and the amount of entanglement sharable between any two sites of
an arbitrary Heisenberg ferromagnet using our scheme. We then apply this to the
realizable case of an open ended chain with nearest neighbor interactions. The
fidelity of quantum state transfer is obtained as an inverse discrete cosine
transform and as a Bessel function series. We find that in a reasonable time, a
qubit can be directly transmitted with better than classical fidelity across
the full length of chains of up to 80 spins. Moreover, the spin-chain channel
allows distillable entanglement to be shared over arbitrarily large distances.Comment: Much improved versio
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Surface mineral crusts: A priority target in search for life on Mars
Mineral crusts are strong candidates in the search for evidence of life during planetary exploration, and should be an important target for examination in impact craters. Crusts in the Haughton crater readily yield a biological signature
Application of remote sensing to selected problems within the state of California
There are no author-identified signficant results in this report
Application of remote sensing to selected problems within the state of California
There are no author-identified significant results in this report
Organic source of nitrogen trials & miscellaneous trials.
1. Nitrogen sources Badgingarra 85BA3 Organic Source of Nitrogen 8SBA4 Interaction of Organic and Inorganic Nitrogen sources 85BAS Miscellaneous Organic Nitrogen Sources 85BA39 Times and Levels of Inorganic Nitrogen Application Lancelin 85M02 Organic sources of nitrogen 85M03 Interaction of Organic and Inorganic Nitrogen Sources 85M04 Miscellaneous Organic Nitrogen Sources 85MOS3 Times and Levels of Inorganic Nitrogen Application Meckering 85N01 Organic Sources of Nitrogen 85N03 Miscellaneous Organic Nitrogen Sources 85NOS9 Times and Levels of Inorganic Nitrogen Application 2. Miscellaneous trials 84M6 Rates of Nitrogen on Wheat - CSIRO Megatrial (E. Harvey) 85M4 Nitrogen and Water on Wheat (with M. Mason) 83WH29 Residual Effects of Crop and Pasture Species on Second Wheat Crop 82WH2 Residual Value of Ripping (4th Year
Static Versus Dynamic Friction: The Role of Coherence
A simple model for solid friction is analyzed. It is based on tangential
springs representing interlocked asperities of the surfaces in contact. Each
spring is given a maximal strain according to a probability distribution. At
their maximal strain the springs break irreversibly. Initially all springs are
assumed to have zero strain, because at static contact local elastic stresses
are expected to relax. Relative tangential motion of the two solids leads to a
loss of coherence of the initial state: The springs get out of phase due to
differences in their sizes. This mechanism alone is shown to lead to a
difference between static and dynamic friction forces already. We find that in
this case the ratio of the static and dynamic coefficients decreases with
increasing relative width of the probability distribution, and has a lower
bound of 1 and an upper bound of 2.Comment: 10 pages, 2 figures, revtex
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