Australian scientists have fabricated a silicon wire just four atoms wide. Although it is a mere 10,000th the size of a human hair, it conducts electricity as well as copper, the researchers say.
The breakthrough could mean a bit of breathing space for chip designers, who would have expected to run into weird quantum effects (loss of conductivity due to electron tunnelling, for instance) at this scale.
But they have shown that Ohm’s law - which describes the relationship between current, resistance and potential difference between two points in a circuit – holds, even in a wire just four atoms across.
The researchers explain that keeping resistivity low at this scale is a challenge, but by spiking the silicon crystal with phosphorus atoms every nanometre or so, the team was able to demonstrate diameter-independent resistivity.
From the abstract: "Atomistic tight-binding calculations conﬁrm the metallicity of these atomic-scale wires, which pave the way for single-atom device architectures for both classical and quantum information processing."
Put another way, it offers a glimpse of a physical architecture to match the theoretical requirements of a quantum computer.
The work was published in early January in the journal Science.