A Superconducting Interferometer with Resistive Point Contacts

K. B. Lobanov, С. И. Бондаренко, A. G. Davydova +1 more

Hisao Miyazaki, Akinobu Kanda, Youiti Ootuka

С. И. Бондаренко

V. A. Khlus

The behavior of a superconducting ring incorporating a point contact, coupled inductively to an oscillatory circuit (hf SQUID), with the rate of change of the magnetic flux in the ring being comparable, to the inverse energy relaxation time of excitations in the superconductor τϵ−1, is examined. For T ∽ Tc the results of the microscopic theory of the nonstationary behavior of point contacts, in which the coupling between the phase difference and the current of the Josephson junction differs from the usual expression I = V/R + Icsinφ in the resistive model, are used. It is shown that the nonequilibrium behavior of a weak link for ω≳τϵ−1 significantly changes the amplitude–frequency and signal characteristics of the SQUID as compared with the case ωτϵ−1≪1, for which the results based on the resistive model are valid. The characteristics of the SQUID in the nonequilibrium situation are sensitive to the ratio between the size of the contact and the mean free path of electrons relative to scattering by impurities.

L.F. Soloveychik, V. S. Étkin

At the present time there is considerable interest in the use of superconducting point contacts (SPC's) for various measurement purposes, in particular the measurement of millimeter and submillimeter band electromagnetic radiation. One problem facing the development of SPC detectors is ensuring their stability and resistance to external influences and noise and the ability to match them to the radiation source over a wide band. A design was developed with a stable uncontrolled SPC in an oversize quasi-optical waveguide for use within a wide band of wavelengths, and some of its characteristics in the 3 cm and 4 mm bands were investigated in the case of ''high resistance'' SPC's with an asymptotic resistance of 10 to 30 ..cap omega.. and critical currents of 5 to 40 ..mu..A.