71,886 research outputs found
Secure Key Distribution by Swapping Quantum Entanglement
We report two key distribution schemes achieved by swapping quantum
entanglement. Using two Bell states, two bits of secret key can be shared
between two distant parties that play symmetric and equal roles. We also
address eavesdropping attacks against the schemes.Comment: 4 pages, 2 figures, 3 tables. The revised version will appear in
Phys. Rev.
Shocks and a Giant Planet in the Disk Orbiting BP Piscium?
Spitzer IRS spectroscopy supports the interpretation that BP Piscium, a gas
and dust enshrouded star residing at high Galactic latitude, is a first-ascent
giant rather than a classical T Tauri star. Our analysis suggests that BP
Piscium's spectral energy distribution can be modeled as a disk with a gap that
is opened by a giant planet. Modeling the rich mid-infrared emission line
spectrum indicates that the solid-state emitting grains orbiting BP Piscium are
primarily composed of ~75 K crystalline, magnesium-rich olivine; ~75 K
crystalline, magnesium-rich pyroxene; ~200 K amorphous, magnesium-rich
pyroxene; and ~200 K annealed silica ('cristobalite'). These dust grains are
all sub-micron sized. The giant planet and gap model also naturally explains
the location and mineralogy of the small dust grains in the disk. Disk shocks
that result from disk-planet interaction generate the highly crystalline dust
which is subsequently blown out of the disk mid-plane and into the disk
atmosphere.Comment: 25 pages, 4 figures, 1 table. Accepted to Ap
A Bit of Secrecy for Gaussian Source Compression
In this paper, the compression of an independent and identically distributed
Gaussian source sequence is studied in an unsecure network. Within a game
theoretic setting for a three-party noiseless communication network (sender
Alice, legitimate receiver Bob, and eavesdropper Eve), the problem of how to
efficiently compress a Gaussian source with limited secret key in order to
guarantee that Bob can reconstruct with high fidelity while preventing Eve from
estimating an accurate reconstruction is investigated. It is assumed that Alice
and Bob share a secret key with limited rate. Three scenarios are studied, in
which the eavesdropper ranges from weak to strong in terms of the causal side
information she has. It is shown that one bit of secret key per source symbol
is enough to achieve perfect secrecy performance in the Gaussian squared error
setting, and the information theoretic region is not optimized by joint
Gaussian random variables
The Likelihood Encoder for Lossy Source Compression
In this work, a likelihood encoder is studied in the context of lossy source
compression. The analysis of the likelihood encoder is based on a soft-covering
lemma. It is demonstrated that the use of a likelihood encoder together with
the soft-covering lemma gives alternative achievability proofs for classical
source coding problems. The case of the rate-distortion function with side
information at the decoder (i.e. the Wyner-Ziv problem) is carefully examined
and an application of the likelihood encoder to the multi-terminal source
coding inner bound (i.e. the Berger-Tung region) is outlined.Comment: 5 pages, 2 figures, ISIT 201
A Rate-Distortion Based Secrecy System with Side Information at the Decoders
A secrecy system with side information at the decoders is studied in the
context of lossy source compression over a noiseless broadcast channel. The
decoders have access to different side information sequences that are
correlated with the source. The fidelity of the communication to the legitimate
receiver is measured by a distortion metric, as is traditionally done in the
Wyner-Ziv problem. The secrecy performance of the system is also evaluated
under a distortion metric. An achievable rate-distortion region is derived for
the general case of arbitrarily correlated side information. Exact bounds are
obtained for several special cases in which the side information satisfies
certain constraints. An example is considered in which the side information
sequences come from a binary erasure channel and a binary symmetric channel.Comment: 8 pages. Allerton 201
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