"The sensitivity of a Josephson junction to an applied magnetic field increases with the area of the junction, which argues for making the devices large so that the control currents can be reduced to a minimum. The switching speed of the junction, however, decreases as the area becomes larger. In recent devices the conflicting demands of speed and sensitivity are met by replacing a single junction with two or more junctions connected by a continuous superconducting loop. Such a multijunction device is called a Josephson interferometer or a superconducting quantum interference device (SQUID)."