Logic gates are the fundamental building blocks of computers, and researchers at the University of Rochester have developed the fastest ones ever built. By chanting graphene and gold with a laser pulse, the new logic gates are a million times faster than existing computers, demonstrating the feasibility of “lightwave electronics.”
Logic gates take two inputs, compare them, and then output a signal based on the result. For example, they may output 1 if both incoming signals are 1 or 0, or if either of them is 1, among other “rules”. Billions of individual logic gates are locked into chips to make up the processor, memory, and other electronic components.
However logic gates do not operate immediately – there are delays on the order of nanoseconds as they process the input. This is fast enough for modern computers, but there is always room for improvement. And now the Rochester team’s new logic gate blows them out of the water, processing information in just femtoseconds, which is a million times smaller than a nanosecond.
To reach these peak speeds, the team made junctions from graphene wire connecting the two gold electrodes. When graphene was combined with a synchronized pair of laser pulses, electrons in the material were excited, sending them blinking toward an electrode, generating an electric current.
By adjusting the phase of the laser pulse, the team was able to generate an explosion of one of two types of charge carriers, which would either add up or cancel each other – the former could be considered a 1 output and the latter a 0 final. The result is an ultrafast logic gate, marking the first proof of concept of an as yet theoretical field known as lightwave electronics.
“It will probably take a very long time before this technology can be used in a computer chip, but at least now we know that lightwave electronics is practically possible,” said study lead researcher Tobias Boulacki.
If these types of lightwave electronic devices ever hit the market, they could be millions of times faster than today’s computers. We currently measure processing speeds in gigahertz (GHz), but these newer logic gates operate on the petahertz (pHZ) scale. Previous studies have determined as to the absolute quantum limit of how fast light-based computer systems can get.
The research was published in the journal Nature,
Source: University of Rochester