Abstract: A method for measurement of distance using the curl-free vector potential radiation field. The system includes current-carrying apparatus for generating a predominantly curl-free vector potential field and apparatus for modulating the current applied to the generating apparatus. The receiving apparatus includes a detecting apparatus with observable properties that vary with the application of an applied curl-free vector potential field, a demodulation apparatus for determining the magnitude of the curl-free vector potential field. The magnitude of the detected curl-free magnetic vector potential field can determine the distance from apparatus generating predetermined periodic changes in the curl-free vector potential field. The vector potential field can be established in conducting and opaque materials which are not capable of transmitting typical electromagnetic radiation.

Abstract: A device for detecting and/or measuring the presence of a magnetic vector potential "field" including two Josephson devices in a Josephson interferometer configuration, a magnetic shielding envelope with apertures arranged so that the magnetic vector potential is confined to the vicinity of one of the two Josephson devices (but not the interferometer loop region) and a means for detecting magnetic flux induced by the interaction of the Josephson device and the magnetic vector potential "field". The detection of the magnetic vector potential offers a more advantageous range of dependence than the magnetic flux density.

Abstract: Apparatus for determination of direction using the curl-free magnetic vector potential field. The apparatus includes apparatus for generating a predominantly curl-free magnetic vector potential field with a predetermined vector field spatial orientation. The field receiving apparatus includes a detecting apparatus with observable properties that vary with magnitude and orientation of an applied curl-free magnetic vector potential field. The apparatus can specify a direction of the field generating apparatus. A periodically rotating vector field can specify a path toward the field generating apparatus. The curl-free magnetic vector potential field can be established in conducting and opaque materials which are not capable of transmitting normal electromagnetic radiation.

Abstract: A system for determining the modulation imposed on a curl-free magnetic vector potential field. The system includes apparatus for detecting the curl-free magnetic vector potential field component by means of a Josephson junction. The magnetic vector potential field interacts with the Josephson junction by varying the phase of the argument of the sine function which determines the Josephson junction current. The output signals of the Josephson junction are coupled to apparatus that can determine the modulation of the detected field. Because the magnitude of the change in the detected curl-free vector potential field causes a proportional change in the phase of the Josephson junction current, the modulation of the field can be established.

Abstract: Apparatus for producing and modulating a magnetic vector potential field having a substantially curl-free component. Detection and demodulation of the curl-free component of the magnetic vector potential field using a Josephson junction device are described of the curl-free magnetic vector field. Examples of modulation of the curl-free magnetic vector field suitable for detection and demodulation by the Josephson junction device are disclosed.