1,297 research outputs found
A Soft X-ray Polarimeter Designed for Broad-band X-ray Telescopes
A novel approach for measuring linear X-ray polarization over a broad-band
using conventional imaging optics and cameras is described. A new type of high
efficiency grating, called the critical angle transmission grating is used to
disperse soft X-rays radially from the telescope axis. A set of
multilayer-coated paraboloids re-image the dispersed X-rays to rings in the
focal plane. The intensity variation around these rings is measured to
determine three Stokes parameters: I, Q, and U. By laterally grading the
multilayer optics and matching the dispersion of the gratings, one may take
advantage of high multilayer reflectivities and achieve modulation factors over
50% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be
used with the Constellation-X optics.Comment: 11 pages, 7 figures, presented at conference 6688 of the SPI
Optimized generation of spatial qudits by using a pure phase spatial light modulator
We present a method for preparing arbitrary pure states of spatial qudits,
namely, D-dimensional (D > 2) quantum systems carrying information in the
transverse momentum and position of single photons. For this purpose, a set of
D slits with complex transmission are displayed on a spatial light modulator
(SLM). In a recent work we have shown a method that requires a single
phase-only SLM to control independently the complex coefficients which define
the quantum state of dimension D. The amplitude information was codified by
introducing phase gratings inside each slit and the phase value of the complex
transmission was added to the phase gratings. After a spatial filtering process
we obtained in the image plane the desired qudit state. Although this method
has proven to be a good alternative to compact the previously reported
architectures, it presents some features that could be improved. In this paper
we present an alternative scheme to codify the required phase values that
minimizes the effects of temporal phase fluctuations associated to the SLM
where the codification is carried on. In this scheme the amplitudes are set by
appropriate phase gratings addressed at the SLM while the relative phases are
obtained by a lateral displacement of these phase gratings. We show that this
method improves the quality of the prepared state and provides very high
fidelities of preparation for any state. An additional advantage of this scheme
is that a complete 2\pi modulation is obtained by shifting the grating by one
period, and hence the encoding is not limited by the phase modulation range
achieved by the SLM. Numerical simulations, that take into account the phase
fluctuations, show high fidelities for thousands of qubit states covering the
whole Bloch sphere surface. Similar analysis are performed for qudits with D =
3 and D = 7.Comment: 12 pages, 7 figure
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