It Only Takes One Molecule To Make A Switch

Researchers have used laser pulses to make a special carbon molecule switch an electron’s path in a predictable way.

For the first time ever, an international research team has demonstrated a switch made from a single molecule called fullerene. Supported in part by the EU-funded PETACom project, the researchers managed to use fullerene to switch the path of an incoming electron in a way they could predict. Their research was published in the journal ‘Physical Review Letters’.

So what does this mean in terms of real-world applications? As described in a press release posted by the University of Tokyo, Japan, the switching process – aided by a carefully tuned laser pulse – can be between three to six orders of magnitude faster than switches in microchips. The actual speed depends on the laser pulses used. This means that if today’s network switches were replaced by fullerene switches, it could lead to computers with capabilities that far exceed those possible with electronic transistors. It could also lead to microscopic imaging devices with unparalleled levels of resolution.

Like a transistor, but faster
“What we’ve managed to do here is control the way a molecule directs the path of an incoming electron using a very short pulse of red laser light,” states study first author Dr Hirofumi Yanagisawa from the University of Tokyo’s Institute for Solid State Physics in the press release. “Depending on the pulse of light, the electron can either remain on its default course or be redirected in a predictable way. So, it’s a little like the switching points on a train track, or an electronic transistor, only much faster. We think we can achieve a switching speed 1 million times faster than a classical transistor. And this could translate to real world performance in computing. But equally important is that if we can tune the laser to coax the fullerene molecule to switch in multiple ways at the same time, it could be like having multiple microscopic transistors in a single molecule. That could increase the complexity of a system without increasing its physical size.”

The fullerene molecule is a series of carbon atoms that form a sphere. When positioned on a metal point, fullerenes orientate in a particular way that enables them to direct electrons predictably. Laser pulses emitted at quadrillionths or even quintillionths of a second towards the fullerene molecules trigger the emission of electrons.

“This technique is similar to the way a photoelectron emission microscope produces images,” explains Dr Yanagisawa. “However, those can achieve resolutions at best around 10 nanometers, or ten-billionths of a meter. Our fullerene switch enhances this and allows for resolutions of around 300 picometers, or three-hundred-trillionths of a meter.”

The results achieved with support from the PETACom (Petahertz Quantum Optoelectronic Communication) project pave the way for switches that perform computational tasks much faster than today’s microchips. However, there are still many obstacles to overcome before we see the fullerene switch-based technology in our computer devices.