Toroidal DC SQUIDs with point-contact junctions

The well-developed technique of a toroidal point-contact rf SQUID has been extended to a dc SQUID. Two point-contacts are made on the symmetry axis of the toroid. A large Nb cavity containing a signal coil is connected to the junctions via a narrow gap. Such geometry allows good coupling of the SQUID to a high-inductance signal coil without increasing the effective SQUID inductance at the Josephson frequency. It is expected that both the shot-noise-limit performance and a high signal coupling will be achieved in this SQUID. We discuss the status of design and the result of preliminary test of the device.