Single Atom in an Ion Trap

In the centre of the picture, a small bright dot is visible – a single positively-charged strontium atom. It is held nearly motionless by electric fields emanating from the metal electrodes surrounding it. (The distance between the small needle tips is about two millimetres.) When illuminated with a specific shade of blue-violet laser light, the atom absorbs and re-emits photons sufficiently quickly for an ordinary camera to capture it in a long exposure photograph. This picture was taken through a window of the ultra-high vacuum chamber that houses the trap. Laser-cooled atomic ions provide a pristine platform for exploring and harnessing the unique properties of quantum physics. They are used to construct extremely accurate clocks or, as in our research, as building blocks for future quantum computers, which could tackle problems that stymie even today’s largest supercomputers.