35,613 research outputs found
AMiBA Wideband Analog Correlator
A wideband analog correlator has been constructed for the Yuan-Tseh Lee Array
for Microwave Background Anisotropy. Lag correlators using analog multipliers
provide large bandwidth and moderate frequency resolution. Broadband IF
distribution, backend signal processing and control are described. Operating
conditions for optimum sensitivity and linearity are discussed. From
observations, a large effective bandwidth of around 10 GHz has been shown to
provide sufficient sensitivity for detecting cosmic microwave background
variations.Comment: 28 pages, 23 figures, ApJ in press
Fast full-color computational imaging with single-pixel detectors
Single-pixel detectors can be used as imaging devices by making use of structured illumination. These systems work by correlating a changing incident light field with signals measured on a photodiode to derive an image of an object. In this work we demonstrate a system that utilizes a digital light projector to illuminate a scene with approximately 1300 different light patterns every second and correlate these with the back scattered light measured by three spectrally-filtered single-pixel photodetectors to produce a full-color high-quality image in a few seconds of data acquisition. We utilize a differential light projection method to self normalize the measured signals, improving the reconstruction quality whilst making the system robust to external sources of noise. This technique can readily be extended for imaging applications at non-visible wavebands
Efficient high-dimensional entanglement imaging with a compressive sensing, double-pixel camera
We implement a double-pixel, compressive sensing camera to efficiently
characterize, at high resolution, the spatially entangled fields produced by
spontaneous parametric downconversion. This technique leverages sparsity in
spatial correlations between entangled photons to improve acquisition times
over raster-scanning by a scaling factor up to n^2/log(n) for n-dimensional
images. We image at resolutions up to 1024 dimensions per detector and
demonstrate a channel capacity of 8.4 bits per photon. By comparing the
classical mutual information in conjugate bases, we violate an entropic
Einstein-Podolsky-Rosen separability criterion for all measured resolutions.
More broadly, our result indicates compressive sensing can be especially
effective for higher-order measurements on correlated systems.Comment: 10 pages, 7 figure
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