Credit: Image courtesy of Argonne National Laboratory/University of Chicago, David Awschalom
Quantum computers use electron spin orientation at a defect site in diamond to store information. The electron spin can be up (+1), down (-1), or anything in between. The spin (left, red arrow) is represented as a vector on a sphere. To change the spin from Position 1 to 2 normally requires two separate optical pulses. However, here a particular single pulse has accomplished the same electronic transition. This single pulse makes the electron travel on a geometric loop, analogous to a Möbius strip (right, a surface with one side and one boundary), such that its position is changed in a robust way after completing the loop.