Error- and Loss-Tolerances of Surface Codes with General Lattice Structures

We propose a family of surface codes with general lattice structures, where the error-tolerances against bit and phase errors can be controlled asymmetrically by changing the underlying lattice geometries. The surface codes on various lattices are found to be efficient in the sense that their threshold values universally approach the quantum Gilbert-Varshamov bound. We find that the error-tolerance of surface codes depends on the connectivity of underlying lattices; the error chains on a lattice of lower connectivity are easier to correct. On the other hand, the loss-tolerance of surface codes exhibits an opposite behavior; the logical information on a lattice of higher connectivity has more robustness against qubit loss. As a result, we come upon a fundamental trade-off between error- and loss-tolerances in the family of the surface codes with different lattice geometries.Comment: 5pages, 3 figure

Multivalued memory effects in electronic phase-change manganites controlled by Joule heating

Non-volatile multivalued memory effects caused by magnetic fields, currents, and voltage pulses are studied in Nd_{0.65}Ca_{0.35}MnO_3 and (Nd_{1-y}Sm_{y})_{0.5}Sr_{0.5}MnO_3 (y=0.75) single crystals in the hysteretic region between ferromagnetic metallic and charge-ordered insulating states. The current/voltage effects observed in this study are explained by the self-heating effect, which enable us to control the colossal electroresistance effects. This thermal-cycle induced switching between electronic solid and liquid states can be regarded as electronic version of atomic crystal/amorphous transitions in phase-change chalcogenides.Comment: 5 pages, 4 figures. to appear in Phys. Rev.

Bifurcation analysis in an associative memory model

We previously reported the chaos induced by the frustration of interaction in a non-monotonic sequential associative memory model, and showed the chaotic behaviors at absolute zero. We have now analyzed bifurcation in a stochastic system, namely a finite-temperature model of the non-monotonic sequential associative memory model. We derived order-parameter equations from the stochastic microscopic equations. Two-parameter bifurcation diagrams obtained from those equations show the coexistence of attractors, which do not appear at absolute zero, and the disappearance of chaos due to the temperature effect.Comment: 19 page

Nodal degenerations of plane curves and Galois covers

Globally irreducible nodes (i.e. nodes whose branches belong to the same irreducible component) have mild effects on the most common topological invariants of an algebraic curve. In other words, adding a globally irreducible node (simple nodal degeneration) to a curve should not change them a lot. In this paper we study the effect of nodal degeneration of curves on fundamental groups and show examples where simple nodal degenerations produce non-isomorphic fundamental groups and this can be detected in an algebraic way by means of Galois coverings.Comment: 16 pages, 3 figure

Multiferroic properties of an \aa kermanite Sr2_2CoSi2_2O7_7 single crystal in high magnetic fields

The magnetic and dielectric properties of \aa kermanite Sr$_2$CoSi$_2$O$_7$ single crystals in high magnetic fields were investigated. We have observed finite induced electric polarization along the c axis in high fields, wherein all Co spins were forcibly aligned to the magnetic field direction. Existence of the induced polarization in the spin-polarized state accompanied with the finite slope in the magnetization curve suggests the possible role of the orbital angular momenta in the excited states as its microscopic origin. The emergence of the field-induced polarization without particular magnetic order can be regarded as the magnetoelectric effects of the second order from the symmetry point of view. A low magnetic field-driven electric polarization flip induced by a rotating field, even at room temperature, has been successfully demonstrated.Comment: 12 pages, 4 figure

Low-dimensional chaos induced by frustration in a non-monotonic system

We report a novel mechanism for the occurrence of chaos at the macroscopic level induced by the frustration of interaction, namely frustration-induced chaos, in a non-monotonic sequential associative memory model. We succeed in deriving exact macroscopic dynamical equations from the microscopic dynamics in the case of the thermodynamic limit and prove that two order parameters dominate this large-degree-of-freedom system. Two-parameter bifurcation diagrams are obtained from the order-parameter equations. Then we analytically show that the chaos is low-dimensional at the macroscopic level when the system has some degree of frustration, but that the chaos definitely does not occur without the frustration.Comment: 2 figure

A Component-based Software Development and Execution Framework for CAx Applications

Digitalization of the manufacturing process and technologies is regarded as the key to increased competitive ability. The MZ-Platform infrastructure is a component-based software development framework, designed for supporting enterprises to enhance digitalized technologies using software tools and CAx components in a self-innovative way. In the paper we show the algorithm, system architecture, and a CAx application example on MZ-Platform. We also propose a new parametric data structure based on MZ-Platform