Electronics have advanced through continuous improvements in microprocessor technology since the 1960s. However, this process of refinement is projected to stall in the near future due to constraints imposed by the laws of physics. Some of these bottlenecks have already taken effect. For instance, the clock speeds of processors are have not exceeded a few gigahertz, or several operations per nanosecond, for the past 20 years, a limitation stemming from the electrical resistance of silicon. This has led to an increasingly urgent global search for superior alternatives to semiconductor electronics.