Hybrid quantum circuit with a superconducting qubit coupled to a spin ensemble

We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus. Using this circuit, we prepare a superposition of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit later on. These results constitute a proof of concept of spin-ensemble based quantum memory for superconducting qubits.     

Density functional study on the activation of methane over Pd2, PdO,and Pd2O clusters

Simple functional models for elementary steps in the total oxidation of methane over supported palladium catalysts were investigated using density functional theory. Three simple cluster models were proposed, namely, the palladium dimer and PdO diatomic and linear Pd₂O, to probe the mechanism of the methane activation on metallic and oxidized palladium phases, respectively. The strongest adsorption was found on Pd₂, where also the C(SINGLE BOND)H bond became easily activated; however, no stable product of the C(SINGLE BOND)H bond scission was indicated. Similar hydrogen activation took place on Pd₂O and, in addition, adsorbed methyl and OH species formed the most stable system after crossing a moderate energy barrier. The same product was previously found stable also in the case of PdO dimer but the activation barrier was high. On the Pd₂O cluster, the process of energy barrier crossing was accomplished in two steps: easy formation of a free hydrogen moiety and actual oxidation, which made the overall process less demanding energetically. © 1997 John Wiley & Sons, Inc.     

Benzo­[i]­naphtho­[c,d]­bi­cyclo­[5.4.1]dodecan‐12‐one

In the title compound, penta­cyclo­[11.8.1.1^3,11.0^7,23.0^15,20]­tricosa‐3,5,7,9,11(23),15,17,19‐octaen‐22‐one, C₂₃H₂₀O, the bi­cyclo­[5.4.1]­dodecan‐12‐one moiety takes a rigid conformation in which the seven‐ and eight‐membered rings take chair and boat–boat forms, respectively. The mol­ecule has a non‐crystallographic mirror symmetry perpendicular to the benzene and naphthalene planes.     

Transmission characteristics of multilayer films composed of electro-optic and dielectric materials

We describe the theoretical evaluation for the transmission characteristics of multilayer films composed of periodic electro-optic and dielectric materials in a variable electric field. The films are assumed to have cavity-type layer stacking structures, which work as a narrow bandpass filter, and their electro-optic material is uni-axial BaTiO₃, whose electro-optic coefficient r₅₁ is larger than 1300 pm/V. The evaluation indicates that films composed of BaTiO₃ and SiO₂ or MgO function as tunable optical bandpass filters, with a tunable range larger than 6 nm for an electric field of less than 4 V/μm.     

Enhanced collectivity in Ni

The neutron-rich nucleus ⁷⁴Ni was studied with inverse-kinematics inelastic proton scattering using a ⁷⁴Ni radioactive beam incident on a liquid hydrogen target at a center-of-mass energy of 80 MeV. From the measured de-excitation γ rays, the population of the first 2⁺ state was quantified. The angle-integrated excitation cross section was determined to be 14(4) mb. A deformation length of δ=1.04(16) fm$\delta =1.04(16)\text{fm}$ was extracted in comparison with distorted wave theory, which suggests that the enhancement of collectivity established for ⁷⁰Ni continues up to ⁷⁴Ni. A comparison with results of shell model and quasi-particle random phase approximation calculations indicates that the magic character of Z=28$Z=28$ or N=50$N=50$ is weakened in ⁷⁴Ni.     

Crystallization and phase transformation of sodium orthoferrites

Upon heating mixtures of α-Fe₂O₃ powder in a sodium hydroxide melt at around 200°C, unstable β-NaFeO₂ crystallizes in the first reaction stage and transforms spontaneously to stable α-NaFeO₂. The process is typical of the Ostwald Step Rule. When γ-Fe₂O₃ is used as the starting material, instead of α-Fe₂O₃, stable α-NaFeO₂ always crystallizes out. It was clearly observed that even though the reactions are of the dissolution and recrystallization type, three-dimensional structural relations can be preserved between the reactant and the product crystals. The nucleation mechanism is discussed on the basis of topotaxy.