Bayesian approach to automatic mass-spectrum peak identification in atom probe tomography.

Identification of mass-spectrum peaks is an indispensable step of an atom-probe tomography reconstruction process and can be a time-consuming procedure, vulnerable to errors, if performed manually. We propose a Bayesian approach to the peak identification problem, based on ranking of candidate ions according to their calculated posterior probabilities. The sample model is reconstructed by iteratively accepting top-ranked ions while taking into account prior information, models of experimental errors, and the already accepted ions. The designed approach has been applied to a number of time-of-flight mass spectra, measured for inorganic samples, and enabled a reliable construction of sample models, consistent with the results of manual analysis. Additionally, a "sliding window" approach for an accurate and efficient peak decomposition of a mass spectrum was established on the base of Fisher information.

Quantum noise radar: superresolution with quantum antennas by accessing spatiotemporal correlations.

We suggest overcoming the "Rayleigh catastrophe" and reaching superresolution for imaging with both spatially and temporally correlated field of a superradiant quantum antenna. Considering far-field radiation of two interacting spontaneously emitting two-level systems, we show that for the measurement of the temporally delayed second-order correlation function of the scattered field, the Fisher information does not tend to zero with diminishing the distance between a pair of scatterers even for non-sharp time-averaged detection. For position estimation of more scatterers, the measurement of the time-delayed function is able to provide a considerable accuracy gain over the zero-delayed function. We also show that the superresolution with the considered quantum antenna can be achieved for both near-field imaging and for estimating the antenna parameters.

Covariant description of X-ray diffraction from anisotropically relaxed epitaxial structures.

A general theoretical approach to the description of epitaxial layers with essentially different cell parameters and in-plane relaxation anisotropy has been developed. A covariant description of relaxation in such structures has been introduced. An iteration method for evaluation of these parameters on the basis of the diffraction data set has been worked out together with error analysis and reliability checking. The validity of the presented theoretical approaches has been proved with a-ZnO on r-sapphire samples grown in the temperature range from 573 K up to 1073 K. A covariant description of relaxation anisotropy for these samples has been estimated with data measured for different directions of the diffraction plane relative to the sample surface.