Junction superconducting

Figure 2 Phase space dependence of the potential energy for a three-junction superconducting loop. U is normalized to the Josephson coupling energy Ej.

Ainong the first TFIz mixers to be constructed were those based on room-temperature Schottky diodes [11]. Over the past decade, new mixers based on superconducting tunnel junctions have been developed that have effective noise levels only a few tunes the quantum limit of [12]. Flowever, certain conditions... 

The promise of 3-D detectors The ideal detector would be able to measure the wavelength dimension of each photon in addition to the two spatial dimensions - a 3-D detector . There is progress being made on 3-D detectors - for example, the superconducting tunneling junction (STJ). However, at present, 3-D detectors are experimental and have only achieved limited wavelength resolution ( /5 < 25) with relatively slow count rates (few kHz per pixel) on a small number of pixels 100 j. Since these devices are experimental and are not being used... 

The theory foresees the possibility of coulomb blockade phenomenon in such junctions. Averim and Likharev had investigated the conditions of vanishing for the Josephson tunneling and demonstrated the possibility of having normal electrodes in the junction. That is, no superconducting electrodes are necessary, and, therefore, coulomb blockade is possible to observe, in principle, even at room temperature. 

The superconducting quantum interference device (SQUID) is formed from a superconducting loop containing at least one Josephson junction. Basically, a SQUID amplifier converts an input current to an output voltage with a transresistance of the order of 107 V/A. The input noise is of the order of 10-11 A/(Hz)1/2. The bandwidth of the SQUID amplifier can be up to 80kHz. The dynamic range in 1 Hz bandwidth can be 150dB. 

The RF SQUID is formed from a single junction in a superconducting loop, which is inductively coupled to a resonant circuit. This is arranged to drive a current round the loop, so that the voltage across the circuit is a measure of the magnetic flux being measured. 

G. Westmacott, F. Zhong, M. Frank, S. Friedrich, S. E. Labov, and W. H. Benner. Investigating Ion-Surface Collisions with a Niobium Superconducting Tunnel Junction Detector in a Time-of-Flight Mass Spectrometer. Rapid Commun. Mass Spectrom., 14(2000) 600-607. 

Superconducting tube, 23 802 Superconducting tunnel junctions (STJs), 23 870-871 tantalum for, 23 829 Superconductivity, 23 801-881 applications of, 23 853 bulk materials applications for, 23 865-870 ceramics, 5 603-605 discovery of, 23 801 in fixed and stabilized levitation, 23 866-867... 

Arrays spaced in LB film possible applications include magnetic control u) superconducting junctions and bubble and magneto-optical devices. 

Fig. 1. Special equipment required to fabricate low-temperature superconducting junctions. Josephson junctions are comprised of aluminum oxide sandwiched between layers of niobium. These trilayer devices are considered vital to the very-high-speed signal processing demands of next-generation computers, radar, and communication systems. Shown in illustration is scientist Dr. Joonhee Kang. (Westinghouse Electric Corporation)...

Fig. 3. Scientist Donald L. Miller holds an integrated circuit chip comprising a high-resolution superconducting analog-to-digital converter. The one-square-cen timeter chip, known as a counting converter, holds promise as an unprecedented combination of high resolution and low power consumption, as needed in future air traffic control radar and infrared space-tracking applications. The 12-bit circuit (Josephson junction) has a resolution of 1 part in 40CK). (Westinghouse Electric Corporation)...

Thin-fiim technology has also played an important role in developing Josephson superconducting devices, which offer outstanding advantages in constructing ultrahigh-speed computers, These are tunnel-junction type devices. 

In the case of conventional (i.e. non-superconductive) metals, the inter pretation of the results of experimental studies on electron tunneling through the "metal-insulator metal junction becomes possible within the framework of the simplest model of non-interacting electrons. Here, the interaction between electrons and between electrons and phonons both inside the barrier and in the bulk of metals are neglected. 

Figure 3. Tunneling spectrum of an A l-A I0x-Pb junction with no intentional dopants, for a 2 mV rms modulation voltage at 4.2 K (---) superconducting electrode, ( ---) Pb normal. Inelastic structures that are present even in a junction...

We will consider a junction with at most one superconducting electrode. Then we can set N2(E+eV-h >)=l. Differentiating Eq. 5 with respect to voltage ... 

Energy Dependence of Current Noise in Superconducting/Normal Metal Junctions... 

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