Researchers from the University of Bonn have just shown how a single atom can be split into its two halves, pulled apart and put back together again. While the word “atom” literally means “indivisible,” the laws of quantum mechanics allow dividing atoms – similarly to light rays – and reuniting them. The researchers want to build quantum mechanics bridges by letting the atom touch adjacent atoms while it is being pulled apart so that it works like a bridge span between two pillars. The results have just been published in the journal Proceedings of the National Academy of Sciences.
Dividing atoms? What sounds like nuclear fission and radioactivity is, however, a precision process using quantum mechanics. The laws of quantum mechanics allow objects to exist in several states simultaneously. This is what the so-called double-slit experiment is based on, where a particle can go through two slits at the same time. The Bonn scientists working with Prof. Dr. Dieter Meschede from the Institute for Applied Physics of the University of Bonn succeeded in keeping a single atom simultaneously in two places that were more than ten micrometers, or one hundredth of a millimeter, apart. This is an enormous distance for an atom. Afterwards, the atom was put back together undamaged.
The fragile quantum effects can only occur at the lowest temperatures and with careful handling. One method is cooling a cesium atom enormously using lasers – to a temperature of a tenth of a million above absolute zero – and then holding it with another laser. This laser beam is key to splitting the atom. It works because atoms have a spin that can go in two directions. Depending on the direction, the atom can be moved to the right or the left by the laser like on a conveyor. Key is that the atom’s spin can be in both directions simultaneously. So, if the atom is moved to the right and left at the same time, it will split. “The atom has kind of a split personality, half of it is to the right, and half to the left, and yet, it is still whole,” explained Andreas Steffen, the publication’s lead author.
But you cannot see the split directly; if you shine a light on the atom to take a picture, the split will collapse immediately. The atom can then be seen in several images; sometimes on the left, sometimes on the right – but never in both places. And yet, the split can be proved successfully by putting the atom back together. Thus an interferometer can be built from individual atoms that can, e.g., be used to measure external impacts precisely. Here, the atoms are split, moved apart and joined again. What will become visible, e.g., are differences between the magnetic fields of the two positions or accelerations since they become imprinted in the quantum mechanical state of the atom. This principle has already been used to very precisely survey forces such as the earth’s acceleration.
via Physicists split an atom using quantum mechanics precision.
