Transistors are getting smaller and smaller, but current technology can't facilitate indefinite miniaturisation.
AMD and Intel often boast smaller manufacturing processes with revised processor architecture releases. Ivy Bridge currently resides at a 22nm process, about 8,000 times smaller than the width of a human hair. At these sizes transistors experience increased leakage current (electron flow which passes though the transistor while in an off state), causing what's known as static power.
Static power dissipation is microprocessor enemy number one. It makes for hotter chips, which become harder to cool as transistor density increases. Intel have already attempted to combat this with their 3D transistor technology, but there's only so far they can take it before hitting another hurdle. There's also the issue of AMD and ARM based processors which don't have access to such technology.
A solution proposed by the University of Notre Dame suggests the use of quantum tunneling. As the name suggests, quantum tunnelling utilises the effects on electrons at a quantum level. Specifically, the quantum property of electrons "tunnelling" through solid material.
Professor Alan Seabaugh from Notre Dame explains the phenomenon, “A transistor today acts much like a dam with a moveable gate. The rate at which water flows, the current, depends on the height of the gate. With tunnel transistors, we have a new kind of gate, a gate that the current can flow through instead of over. We adjust the thickness of the gate electrically to turn the current on and off."
Transistors utilising this technology are known as TFETs (tunnelling field-effect transistors). So far their energy efficiency isn't quite as good as traditional transistors, but there's little doubt that they will soon match and surpass what's available today. Prof. Alan Seabaugh adds, "If we’re successful, the impact will be significant in terms of low-power integrated circuits. These, in turn, raise the possibility of self-powered circuits which, in conjunction with energy-harvesting devices, could enable active health monitoring, ambient intelligence and implantable medical devices."
Amazingly, this technology is far from science fiction. Chances are that you already own a device which relies on the effects of quantum tunnelling to function, namely devices which use flash based memory such as thumb drives and SSDs. This also means that existing circuit designs and manufacturing processes can be used to produce these new TFETs.
Bring on the power efficient chips, we say!