Write your name in letters one atom wide

Scientists have figured out a way to flip the spin of individual atoms caught up in a laser matrix. Using this method, they can literally use the spin of atoms to make two-dimensional designs.

People at county fairs and street festivals who write names on grains of rice are about to get some stiff competition. Scientists have managed to manipulate the spin of single atoms. They can change the spin of carefully arranged atoms so precisely that they can actually make basic designs like squares or straight lines with them. Supposedly this will all pay off in quantum computing, but for now it might just be possible to make the world's tiniest signature. If it happens, it will be accomplished, like all worthy things, by lasers.

First lasers are used to cool down the atoms. Individual atoms can only take in particular frequencies of light. Moving toward oncoming waves makes the crests hit more frequently, while moving away or along the direction will make them hit less frequently. If a laser is tuned precisely, an atom moving toward it will experience the right wavelength for absorption while one moving any other direction won't absorb the light. From the atom's perspective, it's getting 'hit' with photons when it moves one direction, slowing it down. Technically, the atom will pick up this momentum again when it re-emits the photons, but it re-emits the photons in every different direction, so it experiences a net loss of momentum when it moves toward the laser. Using six different lasers, all coming from different directions, the atom is slowed down. This cools the atom.

Next, lasers are used to created an optical lattice. Two beams of light will interfere with each other much the way two sets of waves will. Two troughs will meet and form a larger trough. Two peaks will meet and form a larger peak. And a peak and trough will cancel each other out. If the waves come regularly and in the right sequence from both sides, they form a stable configuration with regular peaks and troughs. The peaks and troughs in an optical lattice form a kind of egg carton shape, keeping the atoms in hollows surrounded by peaks.

Lastly, a laser is employed to change the spin of the atoms. The laser is just a little bit wider than the 'hollow' of the lattice. It changes the shape of the electron shells around the atom, changing the energy of the atom. This nudged the atom to flip its spin.

Scientists found that the process worked 95% of the time, more than enough for the physicist to say, spell out, "Chemists Suck Saline" in a tiny optical web and have it be legible. The process could also be used in quantum computing, but currently smack talk is the most likely application.

Via Nature, Hyperphysics, and USNO.