| 摘要 |
PURPOSE:To obtain a phase difference in a certain zone of a superconductive body from a measured current value and inductance of a first conducting line and a magnetic flux quantum, by making a closed loop of the first superconductive line having a known inductance, a second superconducting line and the zone of the superconductive body the phase difference of which is to be measured. CONSTITUTION:Superconductive lines 2a and 2b are connected to phase difference measuring points A and B on a superconductive body 1 to be measured and a superconductive line 2c is supplied with current from a current source 4a. The superconductive line 2a has a known inductance L. The phase difference between the points A and B psi and the phase difference between the lines 2a and 2b are 2npi. A control line of a Josephson element is connected to the superconductive lines 2a ans 2b so as to detect current and the current on a superconductive line 2c is controlled by a current control circuit 5 so that no current flows on the line 2b. Under these conditions, there is no phase difference in the line 2b and the points B and C have the same phase. The phase difference between the points A and C is equal to psi. Accordingly, under these conditions, current I on the line 2a can be measured by an ammeter without causing disturbance between the points A and B by the measuring current, and psi=2piLI/phio can be calculated with a magnetic flux quantum (constant).
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