Changepoint Problem in Quantumn Setting

In the changepoint problem, we determine when the distribution observed has changed to another one. We expand this problem to the quantum case where copies of an unknown pure state are being distributed. We study the fundamental case, which has only two candidates to choose. This problem is equal to identifying a given state with one of the two unknown states when multiple copies of the states are provided. In this paper, we assume that two candidate states are distributed independently and uniformly in the space of the whole pure states. The minimum of the averaged error probability is given and the optimal POVM is defined as to obtain it. Using this POVM, we also compute the error probability which depends on the inner product. These analytical results allow us to calculate the value in the asymptotic case, where this problem approaches to the usual discrimination problem

Observation of strong electron dephasing in disordered Cu93_{93}Ge4_4Au3_3 thin films

We report the observation of strong electron dephasing in a series of disordered Cu$_{93}$Ge$_4$Au$_3$ thin films. A very short electron dephasing time possessing very weak temperature dependence around 6 K, followed by an upturn with further decrease in temperature below 4 K, is found. The upturn is progressively more pronounced in more disordered samples. Moreover, a ln$T$ dependent, but high-magnetic-field-insensitive, resistance rise persisting from above 10 K down to 30 mK is observed in the films. These results suggest a nonmagnetic dephasing process which is stronger than any known mechanism and may originate from the coupling of conduction electrons to dynamic defects.Comment: to appear in Phys. Rev. Let

Preliminary Clinical Evaluation: The What, Where, How Approach to Scoring

The SCoR is driving for preliminary clinical evaluation (PCE) however; currently there is no method of quantification to assess quality. FRCR has an approach to quantify comments in the rapid reporting examination (CR2B).The aim of this project was to develop a robust scoring system that enables comprehensive image evaluation regardless of profession. An image test bank was administered using RadBench with equal prevalence of normal /abnormal. A random sample of attempts was selected to pilot the scoring model. Sensitivity, specificity and accuracy were calculated. A scoring system (WWH) was developed based on the WHAT (fracture type), WHERE (location), HOW (displacement/angulation) concept (Harcus & Wright 2014) to evaluate the PCE. The results were compared to those obtained using the FRCR model. Calculated actual mean accuracy, sensitivity and specificity scores were 87%, 80% and 93% respectively. FRCR scores were 88%, 80% and 97%. WWH scores were 65%, 37%, and 93%. The FRCR score appears to mirror the actual decision scores however it does not reflect the fact that the PCE for abnormal cases is often incomplete; 'What' 67%, 'Where' 87%, 'How' 7%. The PCE score should ideally correlate with the actual score in order to provide useful information to the referring clinician. Whilst most comments state the location, less states the type, and very few refer to angulation or displacement. Analysis of the PCE is a useful indicator for targeting professional development

CAMERA CALIBRATION TECHNIQUE BY PAN-CLOSEUP EXPOSURES FOR INDUSTRIAL VISION METROLOGY

A high precision and easy-to-use CCD camera calibration technique for industrial vision metrology is discussed. A well-known method is self-calibration by convergent camera configuration of a two- or three-dimensional target field. Only with this technique the central part of a sensor area is precisely calibrated, but off the centre the precision rapidly deteriorates. The presented technique is a simultaneous adjustment of both pan and close exposures, which compensates the lack of distortion data in the fringe area of the sensor and offers both uniform and high-precision calibration. Some patterns of camera configuration are compared in an experiment in terms of the precision and its uniformity over the sensor. And the combination of convergent pan exposures and vertical close exposures is proved the best. 1

Orbital Structure and Magnetic Ordering in Layered Manganites: Universal Correlation and Its Mechanism

Correlation between orbital structure and magnetic ordering in bilayered manganites is examined. A level separation between the $3d_{3z^2-r^2}$ and $3d_{x^2-y^2}$ orbitals in a Mn ion is calculated in the ionic model for a large number of the compounds. It is found that the relative stability of the orbitals dominates the magnetic transition temperatures as well as the magnetic structures. A mechanism of the correlation between orbital and magnetism is investigated based on the theoretical model with the two $e_g$ orbitals under strong electron correlation.Comment: 4 pages, 4 figure

Double-exchange via degenerate orbitals

We consider the double-exchange for systems in which doped electrons occupy degenerate orbitals, treating the realistic situation with double degenerate $e_g$ orbitals. We show that the orbital degeneracy leads in general to formation of anisotropic magnetic structures and that in particular, depending on the doping concentration, the layered magnetic structures of the A-type and chain-like structures of the C-type are stabilized. The phase-diagram that we obtain provides an explanation for the experimentally observed magnetic structures of some over-doped (electron-doped) manganites of the type Nd$_{1-x}$Sr$_x$MnO$_3$, Pr$_{1-x}$Sr$_x$MnO$_3$ and Sm$_{1-x}$Ca$_x$MnO$_3$ with $x > 0.5$.Comment: 4 pages, 1 figur

Anisotropic Spin Diffusion in Trapped Boltzmann Gases

Recent experiments in a mixture of two hyperfine states of trapped Bose gases show behavior analogous to a spin-1/2 system, including transverse spin waves and other familiar Leggett-Rice-type effects. We have derived the kinetic equations applicable to these systems, including the spin dependence of interparticle interactions in the collision integral, and have solved for spin-wave frequencies and longitudinal and transverse diffusion constants in the Boltzmann limit. We find that, while the transverse and longitudinal collision times for trapped Fermi gases are identical, the Bose gas shows diffusion anisotropy. Moreover, the lack of spin isotropy in the interactions leads to the non-conservation of transverse spin, which in turn has novel effects on the hydrodynamic modes.Comment: 10 pages, 4 figures; submitted to PR

Castaing Instability and Precessing Domains in Confined Alkali Gases

We explore analogy between two-component quantum alkali gases and spin-polarized helium systems. Recent experiments in trapped gases are put into the frame of the existing theory for Castaing instability in transverse channel and formation of homogeneous precessing domains in spin-polarized systems. Analogous effects have already been observed in spin-polarized $$ and $^{3}He- ^{4}He$ mixtures systems. The threshold effect of the confining potential on the instability is analyzed. New experimental possibilities for observation of transverse instability in a trap are discussed.Comment: 6 RevTex pages, no figure

Dark-bright magneto-exciton mixing induced by Coulomb interaction in strained quantum wells

Coupled magneto-exciton states between allowed (`bright') and forbidden (`dark') transitions are found in absorption spectra of strained In$_{0.2}$Ga$_{0.8}$As/GaAs quantum wells with increasing magnetic field up to 30 T. We found large (~ 10 meV) energy splittings in the mixed states. The observed anticrossing behavior is independent of polarization, and sensitive only to the parity of the quantum confined states. Detailed experimental and theoretical investigations indicate that the excitonic Coulomb interaction rather than valence band complexity is responsible for the splittings. In addition, we determine the spin composition of the mixed states.Comment: 4 pages, 4 figure

Critical Temperature of Ferromagnetic Transition in Three-Dimensional Double-Exchange Models

Ferromagnetic transition in three-dimensional double-exchange models is studied by the Monte Carlo method. Critical temperature $T_{\rm c}$ is precisely determined by finite-size scaling analysis. Strong spin fluctuations in this itinerant system significantly reduce $T_{\rm c}$ from mean-field estimates. By choosing appropriate parameters, obtained values of $T_{\rm c}$ quantitatively agree with experiments for the ferromagnetic metal regime of (La,Sr)MnO$_{3}$, which is a typical perovskite manganite showing colossal magnetoresistance. This indicates that the double-exchange mechanism alone is sufficient to explain $T_{\rm c}$ in this material. Critical exponents are also discussed.Comment: 4 pages including 1 table and 4 figures, to be published in J. Phys. Soc. Jp