Back in the day, electronics were made with vacuum tubes, which are like little light bulbs that function as amplifiers or switches. In the present, electronics use transistors instead, which do the same thing but can be made tiny and for cheap. NASA researchers have now figured out how to make vacuum tubes on the nanoscale, which could mean faster, more reliable computers.
A vacuum tube is called a vacuum tube because it's a tube with a vacuum in it. There's also a filament inside, and in those respects, vacuum tubes are functionally identical to light bulbs. What makes a vacuum tube part of a computer is the addition of two more bits: a metal grid above the filament, and a plate above the grid with a positive charge. The filament spits out a steady stream of electrons, which zip up towards the plate. Meanwhile, the charge on the metal grid in between can be adjusted to either repel the electron stream or let it through, which is how a vacuum tube can work as either a switch or an amplifier.
Super hardcore stereo systems sometimes still use vacuum tubes for amplification because of the perceptibly warmer sound, but vacuum tubes are also better than those newfangled transistors for two other reasons. First, electrons move faster through the nothing in a vacuum tube than they do through the material of a solid-state transistor, meaning that (all other things being equal) vacuum tubes make for significantly faster processors than transistors. And second, vacuum tubes are beastly. Transistors are fragile little things, and if you send them into space (for example), they tend to get fried by radiation. Not so with vacuum tubes, which are much more radiation-resistant.
The trick, of course, is making a vacuum tube that's just as small and easy to fabricate as a transistor, which has been a very not-easy thing to do, because of the whole "vacuum" thing: mass-producing microscopic vacuum chambers is very expensive. The secret, it turns out, is making the nano vacuum tubes so small that the vacuum itself becomes unnecessary. These new nano vacuum tubes have a filament and a plate that are separated by just 150 nanometers, which is a small enough distance that the odds of an electron colliding with an air molecule is pretty much zero, even without an actual vacuum going on.
The first application for these new nano vacuum tubes is probably going to be in spacecraft, where the radiation resistance will make a huge difference. And since nano vacuum tubes can operate at frequencies that allow them to run ten times faster than silicon transistors, in the longer term, they could be integrated into computers that are much faster than the ones we use today. Also, terahertz operation could mean lots of exciting new chemical sensors for the TSA, according to the researchers. Wonderful, just what we've all been hoping for.
Via Science Mag