The first logic gate to operate at femtosecond timescales could help usher in an era of information processing at petahertz frequencies – a million times faster than today’s gigahertz-scale computers. The new gate, developed by researchers at the University of Rochester in the US and the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in Germany, is an application of lightwave electronics – essentially, shuffling electrons around with light fields – and harnesses both real and virtual charge carriers.

In lightwave electronics, scientists use laser light to guide the motion of electrons in matter, then exploit this control to create electronic circuit elements. “Since light oscillates so fast (roughly a few hundred million times per second), using light could speed up electronics by a factor of roughly 10 000 as compared to computer chips,” says Tobias Boolakee, a laser physicist in Peter Hommelhoff’s group at the FAU and the first author of a study in Nature on the new gate. “With our present work, we have been able propose the idea for a first light field-driven logic gate (the fundamental building block for any computer architecture) and also demonstrate its working principle experimentally.”

In the work, Boolakee and colleagues prepared tiny graphene-based wires connected to two gold electrodes and illuminated them with a laser pulse lasting a few tens of femtoseconds (10^-15 s). This laser pulse excites, or sets in motion, the electrons in graphene and causes them to propagate in a particular direction – so generating a net electrical current.

Researchers at the University of Central Florida are developing new photonic materials which may one day be used to enable ultra-fast, low-power light-based computing. The unique materials referred to as topological insulators, resemble wires that have been flipped inside out, with the insulation on the inside and the current flowing along the exterior.

In order to avoid the overheating issue that today’s ever-smaller circuits encounter, topological insulators could be incorporated into circuit designs to enable the packing of more processing power into a given area without generating heat.

The researchers’ most recent study, which was published on April 28 in the journal Nature Materials, presented a brand-new process for creating the materials that make use of a unique, chained honeycomb lattice structure. The linked, honeycombed pattern was laser etched onto a piece of silica, a material often used to create photonic circuits, by the researchers.