Coincidentally, TU Delft researchers have developed a superconductor that allows electricity to flow in one direction.
A superconducting diode consisting of a thick layer of an atom can reduce the energy consumption of computers enormously. It can also be a breakthrough for superconducting quantum computers.
A diode is an electronic component that allows current to flow in one direction. It is a fundamental part of the transistor, the basic component of modern computers. Diodes and transistors are made of semiconductors that have an electrical resistance, which means that energy is lost in them in the form of heat.
Mathematics can save lives
Supervisors have no resistance. As a result, no energy is lost. However, they can not be used as diodes, because with traditional diodes it is the resistance that causes the electricity to flow in only one direction.
Mazhar Ali, assistant professor of nanoscience at Delft University of Technology, and his colleagues have now demonstrated a superconducting diode for the first time. They placed a two-dimensional layer of a material called niobium-3-bromo-8 between two superconducting layers. When electrons move in one direction through it all, they encounter no resistance. They experience it in the other direction.
“This was not predicted,” Ali says. “We just tried this experimentally – there was no prediction before the experiment.”
The result was so unexpected that Ali and his team do not fully understand how the superconducting diode works. “People have a rough idea, but a strict theory does not exist yet,” Ali says.
Hundreds of times faster
In addition to overthrowing the theory, the discovery can also have important practical applications. Computers and data centers consume between 10 and 20 percent of all electricity in the world. Much of it is lost in the form of heat due to the electrical resistance of transistors. By making superconducting semiconductors, computers could use hundreds of times less power and potentially run hundreds of times faster, Ali said.
The diode not only saves energy, but can also be crucial to the progress of quantum computers. The diode uses a phenomenon called the Josephson effect, a quantum process in which electrons can tunnel through a space between two superconductors.
So-called Josephson junctions are widely used in superconducting quantum computers. The use of a Josephson diode can therefore lead to new types of quantum computers.
“What’s particularly impressive about this result is the fact that you have a Josephson device. Because it involves a lot of extra physics that you would not have in a superconducting wire, for example,” says Jason Robinson, a professor at materials physics at the University of Cambridge.
Ali and his team will now use their discovery to build a superconducting transistor, but challenges await. The current diode operates at about 2 Kelvin, or -271 degrees Celsius. It requires more energy to maintain that temperature than the diode could save.
Ali believes that the diode can work with alternative materials at temperatures above 77 Kelvin – the temperature at which nitrogen is liquid. This would make the diodes energy efficient.
Furthermore, the diode is currently still made in a manual process, where layers of superconducting material are carefully peeled off and stacked on top of each other. This should be automated to make the units scale, Ali says.