We present a kinetic-inductance-based superconducting memory element with non-destructive readout, femtojoule read and write energies, both read and write shunts, which is writeable with pulses shorter than 400 ps. The element utilizes both a high-kinetic-inductance layer made from tungsten silicide as well as a low-kinetic-inductance layer made from niobium. By using tungsten silicide-which has a long (20 ns) thermal time constant-and measuring bit error rates from 10 MHz to 1 GHz, we were able to verify that the thin-film elements could be operated at a data rate at least as fast as the material thermal time constant with a bit error ratio less than 10-6. We also analyze the margins of the device, and outline the characteristics by which a more efficient device may be designed.
Keywords: SFQ; constriction; memory; nMem; nanowire; shunting; yTron.