Detection of magnetic flux with superconducting quantum interference gratings

The authors have carried out finite-inductance calculations of the critical current vs. flux (I/sub c/- Phi ) and voltage vs. flux (V- Phi ) characteristics of superconducting interferometers with many Josephson junctions in parallel. At least two features of the calculations suggest that many junction interferometers, called superconducting quantum interference gratings, might be advantageous for the detection of magnetic flux. First, the voltage noise can be reduced significantly for a given flux-to-voltage transfer coefficient, a feature which is likely to improve the magnetic flux sensitivity of both low- and high-T/sub c/ superconducting devices. In addition, nonuniformity of the junction critical currents appears to have little adverse effect on the predicted diffraction grating such as enhancement and narrowing of the peaks in the I/sub c/- Phi characteristic. Specific schemes for efficiently coupling flux into the device are proposed.<>