A low power 12 bit flux shuttle shift register with Nb technology

A 12 bit Flux Shuttle shift register with a new write and readout gate has been simulated and fabricated using Nb/Al/sub 2/O/sub 3//Nb Josephson junctions. Write, shift and read operations have been tested successfully at 4.2 K. Drive currents are independent from input bit sequence. Although measurements were disturbed by trapped flux, minimum margins are /spl Delta/I=/spl plusmn/10%. The power dissipation of a shift register cell is 9 nW/GHz. Total power losses caused by terminating resistors are 70 /spl mu/W. The minimum line width may be scaled down to 0.5 /spl mu/m, because power losses per unit area of long Flux Shuttle shift registers are extremely low.