Abstract: A qubit (quantum bit) circuit includes a superconducting main loop that is electrically-completed by a serially-interconnected superconducting subloop. The subloop includes two Josephson junctions. A first coil provides a first flux that couples with the main loop but not with the subloop. A second coil provides a second flux that couples with the subloop but not with the main loop.

Abstract: This invention provides a Peltier cooling device generally useful in cooling electronic devices, especially those which are formed of high Tc superconducting materials. The Peltier device of the invention is formed on a micromachined membrane structure to assure good thermal isolation and to intimately integrate the cooling device with the electronic device it is to cool.The membrane is formed by selective, controlled etching of a bulk substrate of a material such as silicon. The Peltier device is formed by selectively implanting or depositing appropriate dopants to form n-doped and p-doped segments on the membrane with a junction between the differently doped segments at the approximate mid-point of the membrane.

Abstract: A superconducting circuit including at least two DC SQUID stages integrated on the same superconducting chip and coupled by a circuit providing efficient transfer of current from the first SQUID stage to the second SQUID stage with large bandwidth. Each SQUID stage is comprised of a superconducting loop having at least two Josephson devices therein, there being shunt resistors across the Josephson devices to render them nonhysteretic. The coupling means between stages is directly connected to the shunt resistors of the first stage and includes a transmission line and an impedance circuit for matching the impedance of the transmission line, where the impedance circuit provides a real impedance over a large frequency range up to approximately the frequency of Josephson oscillation of the Josephson devices in DC SQUID. Feedback from the second SQUID stage to the first SQUID stage improves the input dynamic range and linearity of the circuit.