1,338 research outputs found
Reconstruction of time-dependent coefficients: a check of approximation schemes for non-Markovian convolutionless dissipative generators
We propose a procedure to fully reconstruct the time-dependent coefficients
of convolutionless non-Markovian dissipative generators via a finite number of
experimental measurements. By combining a tomography based approach with a
proper data sampling, our proposal allows to relate the time-dependent
coefficients governing the dissipative evolution of a quantum system to
experimentally accessible quantities. The proposed scheme not only provides a
way to retrieve full information about potentially unknown dissipative
coefficients but also, most valuably, can be employed as a reliable consistency
test for the approximations involved in the theoretical derivation of a given
non-Markovian convolutionless master equation.Comment: 11 pages, 4 figures, revised version published on PR
Ab initio compressive phase retrieval
Any object on earth has two fundamental properties: it is finite, and it is
made of atoms. Structural information about an object can be obtained from
diffraction amplitude measurements that account for either one of these traits.
Nyquist-sampling of the Fourier amplitudes is sufficient to image single
particles of finite size at any resolution. Atomic resolution data is routinely
used to image molecules replicated in a crystal structure. Here we report an
algorithm that requires neither information, but uses the fact that an image of
a natural object is compressible. Intended applications include tomographic
diffractive imaging, crystallography, powder diffraction, small angle x-ray
scattering and random Fourier amplitude measurements.Comment: 7 pages, 4 figures, presented at the XXI IUCr Congress, Aug. 2008,
Osaka Japa
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