1,180 research outputs found
Using Markov Chains for link prediction in adaptive web sites
The large number of Web pages on many Web sites has raised
navigational problems. Markov chains have recently been used to model user navigational behavior on the World Wide Web (WWW). In this paper, we propose a method for constructing a Markov model of a Web site based on past
visitor behavior. We use the Markov model to make link predictions that assist new users to navigate the Web site. An algorithm for transition probability
matrix compression has been used to cluster Web pages with similar transition behaviors and compress the transition matrix to an optimal size for efficient probability calculation in link prediction. A maximal forward path method is used to further improve the efficiency of link prediction. Link prediction has been implemented in an online system called ONE (Online Navigation Explorer) to assist users' navigation in the adaptive Web site
Protecting Quantum Information with Entanglement and Noisy Optical Modes
We incorporate active and passive quantum error-correcting techniques to
protect a set of optical information modes of a continuous-variable quantum
information system. Our method uses ancilla modes, entangled modes, and gauge
modes (modes in a mixed state) to help correct errors on a set of information
modes. A linear-optical encoding circuit consisting of offline squeezers,
passive optical devices, feedforward control, conditional modulation, and
homodyne measurements performs the encoding. The result is that we extend the
entanglement-assisted operator stabilizer formalism for discrete variables to
continuous-variable quantum information processing.Comment: 7 pages, 1 figur
Quantum teleportation of light beams
We experimentally demonstrate quantum teleportation for continuous variables
using squeezed-state entanglement. The teleportation fidelity for a real
experimental system is calculated explicitly, including relevant imperfection
factors such as propagation losses, detection inefficiencies and phase
fluctuations. The inferred fidelity for input coherent states is F = 0.61 +-
0.02, which when corrected for the efficiency of detection by the output
observer, gives a fidelity of 0.62. By contrast, the projected result based on
the independently measured entanglement and efficiencies is 0.69. The
teleportation protocol is explained in detail, including a discussion of
discrepancy between experiment and theory, as well as of the limitations of the
current apparatus.Comment: 17 pages, 19 figures, submitted to PR
Low computational complexity mode division multiplexed OFDM transmission over 130 km of few mode fiber
We demonstrate 337.5-Gb/s MDM-8QAM-OFDM transmission over 130 km of FMF. This confirms that OFDM can significantly reduce the required DSP complexity to compensate for differential mode delay, a key step towards real-time MDM transmission
Gaussian quantum computation with oracle-decision problems
We study a simple-harmonic-oscillator quantum computer solving oracle
decision problems. We show that such computers can perform better by using
nonorthogonal Gaussian wave functions rather than orthogonal top-hat wave
functions as input to the information encoding process. Using the Deutsch-Jozsa
problem as an example, we demonstrate that Gaussian modulation with optimized
width parameter results in a lower error rate than for the top-hat encoding. We
conclude that Gaussian modulation can allow for an improved trade-off between
encoding, processing and measurement of the information.Comment: RevTeX4, 10 pages with 4 figure
Tunneling into Extra Dimension and High-Energy Violation of Lorentz Invariance
We consider a class of models with infinite extra dimension, where bulk space
does not possess SO(1,3) invariance, but Lorentz invariance emerges as an
approximate symmetry of the low-energy effective theory. In these models, the
maximum attainable speeds of the graviton, gauge bosons and scalar particles
are automatically equal to each other and smaller than the maximum speed in the
bulk. Additional fine-tuning is needed in order to assure that the maximum
attainable speed of fermions takes the same value. A peculiar feature of our
scenario is that there are no truly localized modes. All four-dimensional
particles are resonances with finite widths. The latter depends on the energy
of the particle and is naturally small at low energies.Comment: 21 pages, references and comments added, final version to appear in
JHE
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