Superconducting nanoscale memory device. The binary information is encoded in the direction of the electrical current in the loop. When the current flows clockwise, this is considered a '0' state of the memory device. When it flows counter clockwise, this is a '1' state of the memory device. Because the electrons are superconducting, the current flows indefinitely in the loops, making the memory nonvolatile. (a) A photograph of the memory device, consisting of a superconducting strip of Mo75Ge25 (yellow) with a pair of superconducting nanowires forming a closed loop (also yellow): The width of the nanowires is 24 nm and 22 nm, as marked. (b) The critical current, i.e., the maximum current which can be injected into the device without destroying superconductivity, is plotted as a function of magnetic field. To set the memory state '0', we apply positive current targeting the shaded diamond. To set the memory to the state '1', a negative current is applied (as the same external magnetic field). To read out the memory state, the current is ramped to a higher value, as shown by the red rhombus, and the current value at which voltage occurs is measured. Such value is the critical current. Its statistical distribution is shown in (c). The measured value of the critical current depends on the pre-set memory value, '0' or '1'. Thus by measuring the critical current we are able to determine the state of the memory cell.