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Measured and calculated differential cross sections for elastic ͑rotationally unresolved͒ electron scattering from two primary alcohols, methanol ͑CH 3 OH͒ and ethanol ͑C 2 H 5 OH͒, are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. There are no previous reports of experimental electron scattering differential cross sections for CH 3 OH and C 2 H 5 OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well.

Normalized differential cross sections for elastic electron scattering from ethylene (C2H4) are reported. The measurements are obtained using a novel version of the relative flow method with helium as the standard gas. Here, the relative flow method is applied without any prior knowledge of the gas kinetic molecular diameters of either the standard gas whose differential cross sections for electron scattering are known or the unknown gas whose differential cross sections for electron scattering need to be determined. Removal of this restriction is made possible by using an aperture-collimating source of the target gas instead of a conventional tube source. Importantly, the present method is accurate and more rapid than past elastic electron scattering experiments using the relative flow method, which employed tube-collimating gas sources. Our present measurements are used to test the reliability of past measurements for ethylene and so to resolve a recent disagreement between theory and experiment concerning the elastic electron scattering differential cross-section data for ethylene at low energy, by providing experimental values independent of any systematic errors that might arise when estimating gas kinetic molecular diameters for large polyatomics. Our new arrangement also extends the relative flow method to be applicable to gases whose gas kinetic molecular diameters may not be available, such as gaseous biomolecules.

We analyze simple quantum error detection and quantum error correction protocols relevant to current experiments with superconducting qubits. We show that for qubits with energy relaxation the repetitive N -qubit codes cannot be used for quantum error correction, but can be used for quantum error detection. In the latter case it is sufficient to use only two qubits for the encoding. In the analysis we demonstrate a useful technique of unraveling the qubit energy relaxation into "relaxation" and "no relaxation" scenarios. Also, we propose and numerically analyze several two-qubit algorithms for quantum error detection/correction, which can be readily realized at the present-day level of the phase qubit technology.

Normalized doubly differential cross sections (DDCSs) for the electron impact single ionization of Ne and Xe are presented. The Ne measurements are taken at incident energies of 23.5 eV, 25 eV, 30 eV and 40 eV while the Xe measurements are taken at 14 eV, 15 eV and 20 eV. Scattering angles in the experiment range from 15 • to 120 • . The measurements use a moveable target method for an accurate determination of the experimental background. Normalization of the differential data is initially made to available experimental cross sections for excitation of the ground np 6 to the np 5 (n + 1)s excited states of the noble gas and then, if necessary after integration, to available experimental total ionization cross sections. We show that our single differential cross sections, derived from integrating the DDCSs, show a convex profile (frown) for Ne whereas they are concave (smile) for Xe similar to what is observed for He and we suggest a tentative mechanism for this effect.