The new high temperature superconductors have triggered enormous interest not only because of the unique physics involved but also because of their technical potentials, such as the promise for propagation of extremely short electrical pulses. Superconducting band gaps of ~20 THz are predicted assuming BCS theory for the superconductor, making lossless propagation of electrical pulses as short as 50 fs possible.

The authors have demonstrated proximity effect coupling between a high-transition-temperature superconductor and a normal metal. In a device with a 1-μm long gap in a YBa2Cu3O7 film spanned by an Au shunt, the authors observed a DC supercurrent and the AC Josephson effect under microwave irradiation from 2 GHz to 15 GHz. Preliminary work has also begun with Ag shunts. It is concluded that these high quality S-N (superconductor-normal) interfaces should be applicable both to probing the superconducting state in oxide superconductors and to building high-Tc electronic devices

We have achieved considerable success in inducing order into the growth of YBa2Cu3O7 thin films on (100) oriented singlecrystal zirconia substrates. By applying heteroepitaxial growth techniques to the preparation of the substrate material we have been able to increase the amount of texturing in these films. X-ray diffraction studies show a three-fold decrease in the width of the rocking curves of the films after modification of the substrates. The films are oriented with the c axis perpendicular to the substrates.

Electrical time domain measurements and transmission response measurements were made using a 31-cm-long, YBaCuO superconducting thin-film microstrip line and a YBaCuO ground plane, each on separate 1-cm LaGaO3 substrates, with a 125-μm sapphire substrate serving as the dielectric insulator. Degradation of the performance of the line for currents up to the critical-current density and for magnetic fields moderately above the lower critical magnetic field HC1 were evaluated in a variety of simple measurements. In addition, an evaluation of an optically switched segment of a superconducting microstrip line on a zirconia substrate is described. Direct evaluations of pulse distortion are not possible for these long serpentine lines on small substrates due to electromagnetic coupling between adjacent line segments. However, this coupling gives rise to distinctive transmission responses which may aid the evaluation of line performance.

The authors have demonstrated proximity effect coupling between a high-transition-temperature superconductor and a normal metal. In a device with a 1- mu m long gap in a YBa/sub 2/Cu/sub 3/O/sub 7/ film spanned by an Au shunt, the authors observed a DC supercurrent and the AC Josephson effect under microwave irradiation from 2 GHz to 15 GHz. Preliminary work has also begun with Ag shunts. It is concluded that these high quality S-N (superconductor-normal) interfaces should be applicable both to probing the superconducting state in oxide superconductors and to building high-T/sub c/ electronic devices.< >

The critical current density ${J}_{c}$(B,T) is measured to 15 T for c-axis-perpendicular expitaxial thin films of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ with ${J}_{c}$(0,77 K) of order ${10}^{6}$ A/${\mathrm{cm}}^{2}$. Even in the least-favorable perpendicular orientation, critical currents can exceed 5\ifmmode\times\else\texttimes\fi{}${10}^{5}$ A/${\mathrm{cm}}^{2}$ at 20 K in 15-T fields. Thermally activated flux motion (flux creep) is prominently observed, and can in large part explain the magnitude, temperature, and field dependence of the high-field critical currents.

We study the propagation of terahertz bandwidth electrical pulses on high critical current density c-axis oriented YBa2Cu3O7−δ (YBCO) coplanar transmission lines deposited epitaxially on the low dielectric loss substrate lanthanum aluminate (LaAlO3). The losses on the YBCO transmission line are lower than on an equivalent gold line on the same substrate at temperatures below 50 K. At higher temperatures, absorption and dispersion of the ultrashort electrical pulses are observed in reasonable agreement with Mattis–Bardeen theory.

Recently, essentially distortion-free electrical pulse propagation of ~100 GHz bandwidth pulses was reported on YBa2Cu3O7-δ (YBCO) superconducting transmission lines [1]. Here, we report on the launching and propagation of 1-ps electrical pulses onto a superconducting YBCO coplanar stripline. The high-Tc transmission lines are defined on LaGaO3 as a substrate. LaGaO3 allows highly oriented growth of YBCO films and has dielectric losses smaller than cubic zirconia and a low dielectric constant in the d.c. to 1 THz range [2].

We have demonstrated proximity effect coupling between a high transition temperature superconductor and a normal metal. A device with a 1 Am long gold microbridge coupling two evaporated films of YBa2Cu3O7 has a dc supercurrent and exhibits the ac Josephson effect when irradiated with microwaves. These high quality S-N interfaces should have application to fundamental studies of the superconductor as well as to electronic devices.

We have studied the dynamics of a totally interconnected network of nonlinear amplifiers by building model electronic circuits using dense arrays of resistors and discrete amplifiers. Such models have been discussed recently in the context of spin glasses and neural networks. Even without optimization for speed, these circuits easily reproduce and extend the results of computer simulations in considerably less time.

A high-density matrix of α-Si resistors was made to demonstrate a new type of parallel-processing associative memory consisting of an interconnected array of analog amplifiers. The 22 × 22 resistor matrix was made using a technology compatible with conventional VLSI processing. This demonstration circuit can recall up to four 22- bit memories in 1 to 10 µs while correcting errors in the input word of at least 5 bits. This function is difficult to perform efficiently in conventional digital hardware and is the basis for solving a variety of pattern-recognition problems including vision and speech.

We designed an Electronic Neural Network (ENN) memory with 256 neurons on a single chip using a combination of analog and digital VLSI technology plus a custom microfabrication process. Amplifiers with inverting and noninverting outputs are used for the neurons to make inhibitory and excitatory connections. The connections between the individual neurons are provided by amorphous‐silicon resistors which are placed on the CMOS chip in the last fabrication step. This technique allows a very dense packing of the neurons. Electron‐beam direct‐writing is used to pattern the resistors making it easy to change the information stored in the network from one chip to the next.

This paper reviews basic lithographic considerations for current integrated circuit fabrication at the 1 micron level and illustrates methods for making structures with dimensions smaller than 0.1 micron. Many of these methods are well suited to fabricating high-density, resistive neural-networks.

Recent proposals for neural network models indicate that an array of amplifiers coupled to a lattice of wires with resistive components at the crosspoints can perform calculations using collective properties similar to those observed in biological systems. Such a network can perform both memory and processing functions. The promise of the connection matrix processor lies in its very high density, fault tolerance, and massively parallel operation. This paper describes the operation of a neural network and exploratory fabrication techniques for its implementation.

Models for neural function have suggested new ways of designing special-purpose processors. These electronic neural networks mix analog and digital processing. For some applications neural networks may have speed advantages over conventional architectures. This paper provides an introduction to electronic neural computing and describes circuit implementations.