While silicon uses 1.4 watts, the Josephson junction uses 0.005 watt. Generally, a good logical circuit is determined by calculating the product of speed and power. This is very favorable for the Josephson junction. Making a logical circuit was a successful national project. However, it is very difficult to make memory with the Josephson junction.
Japan is the first country in the world making a stable functioning device.
The graph shows the computational speed predicted by the supercomputer project. The graph plots supercomputer performance vs year. A summary table is given below. The plot was meant to be suggestive rather than exact. Usually about 20 decimal numbers in the decimal system are calculated one billion times per second.