Principle Introduction
1962, BD Josephson calculated the tunnel effect of superconductor knot on both sides, and the following important results: 1 Electron pairs can be formed by oxide layer in superconducting The superconducting current does not have a voltage, called the DC Josephson effect. In the outer magnetic field, the maximum superconducting current of superconducting changes with the magnetic field. 2 When the voltage U is added to the knot, high frequency superconducting current is generated, the efficiency is 2 eV / h (H is a Planique constant), which is called the exchange of Josephson effect.
1963, C. Den Andon and J.H. Roeur observed the DC Josephson effect in the experiment. Rarbere confirmed the relationship between the largest superconducting current and magnetic field in the experiment, and Josephson's theory was fully confirmed.
Physical Mechanism
The physical mechanism of Josephson effect is that superconductance is a new long-range ordered phase, and electrons are electronically condensed into electronic pair. Electronics describe the useful sequence parameter φ ( R ). φ ( R ) characterization of the supercourse program, determine its value after some point, The value of other points is also determined. The internal current and need of large block superconductors are equal to zero, and the bit phase is independent of the coordinate, it is a constant. If the intermediate oxide layer is quite thick, the bit correlation is destroyed, φ 1 is independent of φ 2. If the intermediate oxide layer is sufficiently thin, the wave function on both sides penetrates into the oxide layer and associates with each other. When the bit is different from zero, the wave function near the oxide layer must fluctuate, causing the flow of electron pairs. When φ 1- φ 2 is constant, the zero-voltage current is passed through the DC Josephson effect.
The main application
Josephson effect is mainly used in:
1 with Josephson effect, making high sensitivity magnetometer, sensitivity up to 10 Gauss, measuring Magnetic field changes in human heart beating and internal human brain, making "heart magnetic map" and "brain magnetic map". Applied in terms of physical research and geological exploration.
2 In the measurement, the voltage reference monitoring system was developed in the early 1970s. Josephson effect is also used to make high-precision test gauges, voltage comparator, current comparator, and precision measurements for RF voltage, current, power, and attenuation.
3 is used as a tympal wave, sub-millimeter wave detector and mixer, which has the advantage of low noise, frequency bandwidth, and small loss.
4 Josephon is used as a switch and memory component in a computer. The switch speed has reached 10 picoseconds, and the power consumption is also small.