The Effect of Participation in Government Consortia on the R&D Productivity of Firms: A Case Study of Robot Technology in Japan

This paper examines the effect of participation in government-sponsored R&D consortia on the R&D productivity of firms in the case of robot technology in Japan. We attempt to provide a new empirical analysis and discussions on the issue of government project evaluation by using indicators of the quality of patents, by investigating the impact of the evolution of government programs, and comparing government-sponsored R&D consortia with collaborative R&D among firms. Using indicators of the quality of patents which enables us to provide an estimation of quality-adjusted research productivity, we find that participation in government programs has a positive impact on the research productivity of participating firms, but the impact of participation became much higher after the design of government programs in this field changed in the late 1990s. Also, we find that participation in government-sponsored consortia has a greater impact on research productivity than participation in collaborative R&D among firms. This may support government involvement in R&D as a coordinator of R&D collaboration.industrial policy, robot thchnology, Japanese innovation system, collaborative R&D

Macroscopic quantum dynamics of pi-junctions with ferromagnetic insulators

We theoretically investigate the macroscopic quantum dynamics of a pi junction with a superconductor (S) and a multiferroic material or a ferromagnetic insulator (FI). By deriving the effective action from a microscopic Hamiltonian, a pi-junction qubit (a S-FI-S superconducting quantum interference device ring) is proposed. In this qubit, a quantum two-level system is spontaneously generated and the effect of the quasiparticle dissipation is found to be very weak. These features make it possible to realize a quiet qubit with high coherency. We also investigate macroscopic quantum tunneling (MQT) in current-biased S-FI-S pi junctions and show that the influence of the quasiparticle dissipation on MQT is negligibly small.Comment: 4 pages, 2 figure

Topological superconductivity in bilayer Rashba system

We theoretically study a possible topological superconductivity in the interacting two layers of Rashba systems, which can be fabricated by the hetero-structures of semiconductors and oxides. The hybridization, which induces the gap in the single particle dispersion, and the electron-electron interaction between the two layers leads to the novel phase diagram of the superconductivity. It is found that the topological superconductivity {\it without breaking time-reversal symmetry} is realized when (i) the Fermi energy is within the hybridization gap, and (ii) the inter-layer interaction is repulsive, both of which can be satisfied in realistic systems. Edge channels are studied in a tight-binding model numerically, and the several predictions on experiments are also given.Comment: 5 page

Theory of Macroscopic Quantum Tunneling and Dissipation in High-Tc Josephson Junctions

We have investigated macroscopic quantum tunneling (MQT) in in-plane high-Tc superconductor Josephson junctions and the influence of the nodal-quasiparticle and the zero energy bound states (ZES) on MQT. We have shown that the presence of the ZES at the interface between the insulator and the superconductor leads to strong Ohmic quasiparticle dissipation. Therefore, the MQT rate is noticeably suppressed in comparison with the c-axis junctions in which ZES are completely absent.Comment: 4 pages. 1 figur

Effect of zero energy bound states on macroscopic quantum tunneling in high-Tc superconductor junctions

The macroscopic quantum tunneling (MQT) in the current biased high-Tc superconductor Josephson junctions and the effect of the zero energy bound states (ZES) on the MQT are theoretically investigated. We obtained the analytical formula of the MQT rate and showed that the presence of the ZES at the normal/superconductor interface leads to a strong Ohmic quasiparticle dissipation. Therefore, the MQT rate is noticeably inhibited in compared with the c-axis junctions in which the ZES are completely absent.Comment: 4 pages, 1 figure, comment and reference about recent experiment adde

Josephson pi-state in a ferromagnetic insulator

We predict anomalous atomic-scale 0-pi transitions in a Josephson junction with a ferromagnetic-insulator (FI) barrier. The ground state of such junction alternates between 0- and pi-states when thickness of FI is increasing by a single atomic layer. We find that the mechanism of the 0-pi transition can be attributed to thickness-dependent phase-shifts between the wave numbers of electrons and holes in FI. Based on these results, we show that stable pi-state can be realized in junctions based on high-Tc superconductors with La$_2$BaCuO$_5$ barrier.Comment: 4 pages, 3 figures, Phys. Rev. Lett. (2010) in pres