New BSFQ Circuit Designs with Wide Margins (2008)
Abstract-Recently we have proposed novel Boolean Sin-gle-Flux-Quantum (BSFQ) circuits, which just like CMOS cir-cuits support Boolean primitives directly, and do not require local synchronization for...
Active Perception Based on Reinforcement Learning (2008)
Katsunari Shibata, Tetsuo Nishino, Yoichi Okabe
A reinforcement learning system for the active perception is proposed. This system has a movable sensor and a neural network, and learns not only recognition but also appropriate sensory motions from...
Stochastic Resonance in a Pulse Neural Network With a Propagational Time Delay (2007)
Takashi Kanamaru, Yoichi Okabe
Stochastic resonance in a coupled FitzHugh-Nagumo equation with a propagational time delay is investigated. With an appropriate set of parameter values, i.e., the frequency of the periodic input, the...
Smoothing-Evaluation Method in Delayed Reinforcement Learning (2007)
Katsunari Shibata, Yoichi Okabe
Another method of delayed reinforcement learning is proposed. There are two neural networks in a robot's brain, those are a eval-uation network and a motion network. The evaluation network is...
Reinforcement Learning When Visual Sensory Signals are Directly Given as Inputs (2007)
Katsunari Shibata, Yoichi Okabe
shibata @ okabe.rcast.u-tokyo.ac.jp okabe @ okabe.rcast.u-tokyo.ac.jp It is shown that a neural-network based learning
Simple Learning Algorithm for Recurrent Networks to Realize Short-Term Memories (2007)
Katsunari Shibata, Yoichi Okabe, Koji Ito
A simple supervised leceming algorithm for recurrein neural networks ' is proposed It needs ' only O(n 2) memories ' and 0(1 2) calculations where n is the number of neurons, by...
A novel global self-timing methodology for BSFQ circuits (2003)
Recently we have proposed Boolean single-flux-quantum (BSFQ) circuits, which like CMOS circuits directly support Boolean primitives, and do not require local synchronization for their elementary...
HTS Quasi-Particle Injection Devices for Interfaces between SFQ and CMOS Circuits. (2002)
Shiga, Hidehiro, Okabe, Yoichi
We have fabricated a prototype of interface devices between SFQ and CMOS circuits using HTS quasi-particle injection devices. By the injection of quasi-particles, the bridge area becomes resistive...
Interface-Modified Ramp-Type Josephson Junctions in Trilayer Structures. (2002)
Matsushita, Masayuki, Okabe, Yoichi
We have fabricated ramp-type Josephson junctions in trilayer structures. A bilayer of YBa_2Cu_3O_ (YBCO)/CeO_2 was deposited on a SrTiO_3 (100) substrate. Then, circle patterns with a diameter of 2...
Quasi-particle injection devices for interfaces between superconductors and semiconductors. (2001)
Shiga, Hidehiro, Okabe, Yoichi
We have fabricated an injection type 3-terminal device for interface between superconductor and semiconductor circuits using a high temperature superconductor. When quasi-particles are injected from...
New BSFQ circuit designs with wide margins (2001)
Recently we have proposed novel Boolean Single-Flux-quantum (BSFQ) circuits, which Just like CMOS circuits support Boolean primitives directly, and do not require local synchronization for each...
Stochastic resonance in a pulse neural network with a propagational time delay. (2000)
Kanamaru, Takashi, Okabe, Yoichi
Stochastic resonance in a coupled FitzHugh–Nagumo equation with a propagational time delay is investigated. With an appropriate set of parameter values, i.e. the frequency of the periodic input,...
Fast combinatorial optimization with parallel digital computers (2000)
This paper presents an algorithm which realizes fast search for the solutions of combinatorial optimization problems with parallel digital computers. With the standard weight matrices designed for...
Associative memory retrieval induced by fluctuations in a pulsed neural network. (2000)
Kanamaru, Takashi, Okabe, Yoichi
An associative memory retrieval in a pulse neural network composed of the FitzHugh-Nagumo neurons is investigated. The memory is represented in the spatio-temporal ring pattern of the neurons, and...
Ph.D. Thesis Roles of Fluctuations in Pulsed Neural Networks (2000)
Supervisor Professor, Yoichi Okabe, Takashi Kanamaru
Concerning the fluctuation which is observed in biological sensory systems and cortical neuronal networks, the roles of fluctuations in pulsed neural networks are investigated. As a model of a single...
Fabrication of YBaCuO junctions by the irradiation of focused ionbeam. (1999)
Shiga, Hidehiro, Soutome, Yoshihisa, Okabe, Yoichi
We have fabricated Josephson junctions in YBa2Cu3 O7-δ (YBaCuO) thin films by the irradiation of focused ion beam (FIB). We used Be2+ ions with the energy of 200 keV. When the fluence of Be2+ ions...
SFQ data processing with set/reset information (1999)
Kodaka, Hiroki, Hosoki, Tetsu, Kitagawa, Manabu, Okabe, Yoichi
We propose a new class of SFQ logic circuits. In this new approach, an SFQ pulse represents the transition between "zero" and "one". By using these two bits of information, a one-to-one...
Stochastic resonance for the superimposed periodic pulse train. (1999)
Kanamaru, Takashi, Horita, Takehiko, Okabe, Yoichi
Stochastic Resonance in a coupled FitzHugh–Nagumo equation is investigated. The optimal noise intensity and the optimal input frequency, which maximize the signal to noise ratio of the output...
Y-BA-CU-O/NB JOSEPHSON TUNNEL-JUNCTIONS (1999)
Nakayama, Akiyoshi, Inoue, Atsuki, Takeuchi, Kiyoshi, Ito, Hiroyuki, Okabe, Yoichi
We have fabricated Y-Ba-Cu-O/ Au/AIOx/Nb and Y-Ba-Cu-O/AIOx/Nb Josephson tunnel junctions using electron-beam evaporation of A1 and Nb films and natural oxidation. Sintered Y-Ba-Cu-0 have been used...
Selective retrieval of memory and concept sequences through neuro-windows (1999)
This letter presents a crosscorrelational associative memory model which realizes selective retrieval of pattern sequences. When hierarchically correlated sequences are memorized, sequences of the...
Katsunari Shibata, Koji Ito, Yoichi Okabe
Two of us has proposed a direct-vision-based reinforcement learning on the neural-network system, in which raw visual sensory signals ' are directly used as' the inputs ' of the neural...
Soutome, Yoshihisa, Okabe, Yoichi
The YBa2Cu3O7-delta co-planer Josephson junctions by Focused Ion Beam were fabricated by changing the width and the thickness of a YBa2Cu3O7-delta thin film The magnetic properties of the junctions...
Inductance computation of microscopic superconducting loop (1997)
Nakazato, Takaaki, Okabe, Yoichi
Aimed for the design of superconducting digital circuits, a direct method is proposed to estimate the inductance of three-dimensional microscopic superconducting loop. This method directly computes...
OPTIMIZATION OF A DC-SQUID MAGNETOMETER TO MINIMIZE THE FIELD RESOLUTION (1995)
The circuit parameters of a dc SQUID magnetometer have been optimized by computer simulations. Our principle of optimization is to minimize the field resolution. We have optimized the circuit...
Nakayama, Akiyoshi, Nagashima, Haruo, Shimada, Junichi, Okabe, Yoichi
We have fabricated Nb/AlOX/Nb Josephson tunnel junctions using a sputtering apparatus with a load-lock system. The junctions that had 50 mu m x 50 mu m area showed a V-m value (the product of the...
FABRICATION OF FIELD-EFFECT DEVICES BASED ON YBACUO/PRBACUO/YBACUO JUNCTIONS (1995)
Kimura, Hiroshi, Okabe, Yoichi, Kamijo, Hiroshi
In order to investigate an electric field effect in the junction, the three terminal device was fabricated. When the gate voltage of +2V (E=7x10(4) V/cm) was applied, the drain-source resistance...
Soutome, Yoshihisa, Gheem, YG, Okabe, Yoichi
Thin film of YBa(2)Cu3O(7-delta) grown on the MgO substrate damaged by a focused ion beam loses superconductivity due to an abnormal growth. We have fabricated a YBa2Cu3O7-delta co-planar Josephson...
SUPERCONDUCTION AND NORMAL CONDUCTING CHARACTERISTICS OF (YXPR1-X)BA2CU3O7-DELTA THIN-FILMS (1995)
Miyazaki, Masayuki, Okabe, Yoichi
The ratio of Yttrium (Y) to Praseodymium (Pr) is varied in (YxPr1-x)Ba2Cu3O7-delta (YPBCO) thin films to consider the relation between superconducting YBa2Cu3O7-delta (YBCO) and insulating...
Nakayama, Akiyoshi, Okabe, Yoichi
Superconducting hetero-junction made of the p-wave superconductor and the normal s-wave superconductor has been considered. Bogoliubov transformation in the p-wave superconductor has been obtained by...
CHARACTERISTICS OF Y-BA-CU-O/NB AND BI-SR-CA-CU-O/NB TUNNEL-TYPE JOSEPHSON-JUNCTIONS (1991)
Nakayama, Akiyoshi, Matsui, Toshiyuki, Okabe, Yoichi
We have fabricated Y-Ba-Cu-O/Nb and Bi-Sr-Ca-Cu-O/Nb tunnel-type Junctions and observed the DC and AC Josephson effects. Gold thin films were deposited for an inter-layer to protect the reaction...
GAP MEASUREMENT IN NB/NBOX/AL INJECTION CONTROLLED PLANAR 3 TERMINAL DEVICES (1989)
Takeuchi, Kiyoshi, Okabe, Yoichi
Characteristics of Nb/NbOx/Al injection controlled planar three terminal superconducting devices (injection controlled links) have been studied experimentally. A built-in Nb/AlOx/Nb Josephson...
Y-BA-CU-O THIN-FILMS BY EVAPORATING THE 3 ELEMENTS USING RESISTIVE HEATING (1989)
Nakayama, Akiyoshi, Ochi, Nobuhiro, Takeuchi, Kiyoshi, Ito, Hiroyuki, Okabe, Yoichi
HIGH-FREQUENCY PROPERTIES OF ALL-NBN NANOBRIDGES WITH GAP STRUCTURE IN IV CURVES (1987)
Hamasaki, K, Yakihara, I, Wang, Z, Yamashita, T, Okabe, Yoichi
AI I-NbN nanobridges with gap s t r u c t u r e i n I-V curves have been reproducibly constructed using RIE and l i f t - o f f techniques. The nanobridges had a width of 2 Dm, and a thickness of
PROPOSAL OF UNILATERAL SINGLE-FLUX-QUANTUM LOGIC GATE (1985)
Miyake, H, Fukaya, N, Okabe, Yoichi, Sugano, T
A new type of single flux quantum logic gate is proposed, which can perform unilateral propagation of signal without using three-phase clock. This gate is designed to be built with bridge-type...
ION-SENSITIVE FIELD-EFFECT TRANSISTORS WITH INORGANIC GATE OXIDE FOR PH SENSING (1982)
Akiyama, Tatsuo, Ujihiar, Yusuke, Okabe, Yoichi, Sugano, Takuo, Niki, Eiji
Ion-sensitive fieldeffect transistors (ISFET’s) have been fabricated by using silicon fiims on sapphire substrates (SOS). Using this structure Si02, Zr02, and TazO5 films are examined as...
PROPOSAL OF SINGLE-FLUX-QUANTUM LOGIC DEVICE (1980)
Tamura, Hirotaka, Okabe, Yoichi, Sugano, Takuo
A new type of logic gate that can be designed using a nonhysteretic Josephson weak link is proposed. The basic component of the proposed device is a one-junction interferometer, and a logic state is...