Majorana-based fermionic quantum computation

Because Majorana zero modes store quantum information non-locally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majoranas to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majoranas for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum phase estimation algorithms, proposed for quantum chemistry simulations. Because we avoid the Jordan-Wigner transformation, our scheme has a lower overhead for implementing both of these algorithms, and the simulation of Trotterized Hubbard Hamiltonian in $\mathcal{O}(1)$ time per unitary step. We finally demonstrate magic state distillation in our fermionic architecture, giving a universal set of topologically protected fermionic quantum gates.Comment: 4 pages + 4 page appendix, 4 figures, 2 table

Yarkovsky-O’Keefe-Radzievskii-Paddack effect on tumbling objects

A semi-analytical model of the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect on an asteroid spin in a non-principal axis rotation state is developed. The model describes the spin-state evolution in Deprit–Elipe variables, first-order averaged with respect to rotation and Keplerian orbital motion. Assuming zero conductivity, the YORP torque is represented by spherical harmonic series with vectorial coefficients, allowing us to use any degree and order of approximation. Within the quadrupole approximation of the illumination function we find the same first integrals involving rotational momentum, obliquity and dynamical inertia that were obtained by Cicaló & Scheeres. The integrals do not exist when higher degree terms of the illumination function are included, and then the asymptotic states known from Vokrouhlický et al. appear. This resolves an apparent contradiction between earlier results. Averaged equations of motion admit stable and unstable limit cycle solutions that were not previously detected. Non-averaged numerical integration by the Taylor series method for an exemplary shape of 3103 Eger is in good agreement with the semi-analytical theory

Development of the interatrial wall during the ontogenesis of foetuses and children up to one year of age

Background: The foramen ovale, present in foetal interatrial septum, plays an important role during foetal life. During delivery, foramen ovale closes and becomes fossa ovalis, starting the pulmonary circulation. The aim of our study was to describe the growth of the interatrial wall and changes in location of the foramen ovale, and fossa ovalis during the ontogenesis in the human hearts.Materials and methods: The study was performed on post-mortem material obtained from 92 human hearts from 22nd week of foetal life up to 1 year of age, fixed in a 4% formalin solution.Results: The interatrial wall size in the studied development period was greater in the horizontal than in the vertical dimension. During ontogenesis up to 1 year old, the anterior and inferior parts of the interatrial wall increased their shares considerably by 8% and 6%, respectively. The percentage participation of foramen ovale in the interatrial wall construction in the foetal period formed more than 50% of its size and fairly decreased reaching in infants about 39%.Conclusions: Our study demonstrated that during ontogenesis, from the foetal period to infancy, the parts of the interatrial wall increase their dimensions unevenly. The foramen ovale growth is smaller, compared to the rest of the interatrial wall development. On the basis of our data we can assume that the foramen ovale centre tends to be found in the postero-inferior quadrant of the interatrial wall (foetuses) and in postero-superior quadrant of the interatrial wall — in infants

Stress field and spin axis relaxation for inelastic triaxial ellipsoids

A compact formula for the stress tensor inside a self-gravitating, triaxial ellipsoid in an arbitrary rotation state is given. It contains no singularity in the incompressible medium limit. The stress tensor and the quality factor model are used to derive a solution for the energy dissipation resulting in the damping (short axis mode) or excitation (long axis) of wobbling. In the limit of an ellipsoid of revolution, we compare our solution with earlier ones and show that, with appropriate corrections, the differences in damping times estimates are much smaller than it has been claimed. This version implements corrections of misprints found in the MNRAS published text.Comment: 14 pages, 6 figures, published in Monthly Notices RAS (containing misprints

Threshold Hyperon Production at COSY-11

The Lambda, Sigma0 and Sigma+ hyperon production in NN collisions is studied at the COSY - 11 installation in order to investigate the production mechanism as well as to extract information about the Y-N interaction.Comment: 3 pages, 2 figure

Drift chamber with a c-shaped frame

We present the construction of a planar drift chamber with wires stretched between two arms of a c-shaped aluminium frame. The special shape of the frame allows to extendthe momentum acceptance of the COSY-11 detection system towards lower momenta without suppressing the high momentum particles. The proposed design allows for construction of tracking detectors covering small angles with respect to the beam, which can be installed and removed without dismounting the beam-pipe. For a three-dimensional track reconstruction a computer code was developed using a simple algorithm of hit preselection.Comment: submitted to Nucl. Instr. & Meth

Search for Bremsstrahlung radiation in quasi-free n p --> n p gamma reactions

Due to the high sensitivity of the N N --> N N gamma reaction to the nucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to investigate details of the nucleon-nucleon interaction. Such investigations can be performed at the cooler synchrotron COSY in the Research Centre Juelich, by dint of the COSY-11 detection system. The results of the identification of Bremsstrahlung radiation emitted via the d p --> d p gamma reaction in data taken with a proton target and a deuteron beam are presented and discussed.Comment: 3 pages; Presented at Meson 2004: 8th International Workshop on Meson Production, Properties and Interaction, Krakow, Poland, 4-8 June 2004; Submitted to International Journal of Modern Physics

Production of Eta Mesons in Proton-Proton Collisions Close to Threshold

A brief experimental overview on the close-to-threshold eta meson production in proton-proton interactions is presented and the available observables in measurements with unpolarized and polarized beam and target are discussed.Comment: 4 pages; Presented at Meson 2004: 8th International Workshop on Meson Production, Properties and Interaction, Krakow, Poland, 4-8 June 2004; Submitted to International Journal of Modern Physics

Near threshold eta meson production in dp collisions

Preliminary results of recent measurements of the near threshold eta meson production in the dp-->dp eta reaction are presented. The experiment was performed at the COSY-Juelich accelerator with the use of the COSY-11 detection system. Data were taken for three values of deuteron beam momenta corresponding to excess energies of 3.2, 6.1 and 9.2 MeV. The energy dependence of the total cross section confirms a strong effect of the final state interaction.Comment: Talk given at 9th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 9-13 June 2006. 5 pages, 3 figure