As the name suggests, electronics use electrons but what if we started using something else? Researchers at the University of California – Berkeley are working on building a magnetic computer with components that use nanomagnets inside of chips. Instead of using an electric current to move data, nanometer-sized bar magnets would be used instead, for memory, logic, and switching operations. This is not just for curiosity, as a magnetic computer could be a great deal more efficient than an electronic one. How much more efficient? One million times more efficient, as only 18 millielectron volts of energy would be lost per operation at room temperature; the Landauer limit. This limit is the smallest amount of energy that can dissipate and be lost from an operation. Of course, that is what the calculations say the magnetic computers could reach and reality may differ, but to even be a factor of ten off is still a major accomplishment. Also, as the Landauer limit varies with temperature, the colder the circuits the more efficient they can be.
The challenges to making a magnetic computer are the wires and transistors, as the magnets can already act as the memory.