869 research outputs found
Experimental Violation of Bell's Inequality in Spatial-Parity Space
We report the first experimental violation of Bell's inequality in the
spatial domain using the Einstein--Podolsky--Rosen state. Two-photon states
generated via optical spontaneous parametric downconversion are shown to be
entangled in the parity of their one-dimensional transverse spatial profile.
Superpositions of Bell states are prepared by manipulation of the optical
pump's transverse spatial parity--a classical parameter. The Bell-operator
measurements are made possible by devising simple optical arrangements that
perform rotations in the one-dimensional spatial-parity space of each photon of
an entangled pair and projective measurements onto a basis of even--odd
functions. A Bell-operator value of 2.389 +- 0.016 is recorded, a violation of
the inequality by more than 24 standard deviations.Comment: 10 pages, 3 figures, 1 Tabl
Simple model for 1/f noise
We present a simple stochastic mechanism which generates pulse trains
exhibiting a power law distribution of the pulse intervals and a
power spectrum over several decades at low frequencies with close to
one. The essential ingredient of our model is a fluctuating threshold which
performs a Brownian motion. Whenever an increasing potential hits the
threshold, is reset to the origin and a pulse is emitted. We show that
if increases linearly in time, the pulse intervals can be approximated
by a random walk with multiplicative noise. Our model agrees with recent
experiments in neurobiology and explains the high interpulse interval
variability and the occurrence of noise observed in cortical
neurons and earthquake data.Comment: 4 pages, 4 figure
High-sensitivity imaging with multi-mode twin beams
Twin entangled beams produced by single-pass parametric down-conversion (PDC)
offer the opportunity to detect weak amount of absorption with an improved
sensitivity with respect to standard techniques which make use of classical
light sources. We propose a differential measurement scheme which exploits the
spatial quantum correlation of type II PDC to image a weak amplitude object
with a sensitivity beyond the standard quantum limit imposed by shot-noise.Comment: 13 pages, 8 figure
Polarization-sensitive quantum-optical coherence tomography
We set forth a polarization-sensitive quantum-optical coherence tomography
(PS-QOCT) technique that provides axial optical sectioning with
polarization-sensitive capabilities. The technique provides a means for
determining information about the optical path length between isotropic
reflecting surfaces, the relative magnitude of the reflectance from each
interface, the birefringence of the interstitial material, and the orientation
of the optical axis of the sample. PS-QOCT is immune to sample dispersion and
therefore permits measurements to be made at depths greater than those
accessible via ordinary optical coherence tomography. We also provide a general
Jones matrix theory for analyzing PS-QOCT systems and outline an experimental
procedure for carrying out such measurements.Comment: 15 pages, 5 figures, to appear in Physical Review
Human Intent Prediction Using Markov Decision Processes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97080/1/AIAA2012-2445.pd
Entangled Electronic States in Multiple Quantum-Dot Systems
We present an analytically solvable model of colinear, two-dimensional
quantum dots, each containing two electrons. Inter-dot coupling via the
electron-electron interaction gives rise to sets of entangled ground states.
These ground states have crystal-like inter-plane correlations and arise
discontinously with increasing magnetic field. Their ranges and stabilities are
found to depend on dot size ratios, and to increase with .Comment: To appear in Physical Review B (in press). RevTeX file. Figures
available from [email protected]
Scaling-violation phenomena and fractality in the human posture control systems
By analyzing the movements of quiet standing persons by means of wavelet
statistics, we observe multiple scaling regions in the underlying body
dynamics. The use of the wavelet-variance function opens the possibility to
relate scaling violations to different modes of posture control. We show that
scaling behavior becomes close to perfect, when correctional movements are
dominated by the vestibular system.Comment: 12 pages, 4 figures, to appear in Phys. Rev.
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