In a special arrangement of atomic spins, Max Planck physicists have measured the properties of the so-called Haldane phase in an experiment. To do so, they used a quantum mechanical trick.
In some materials, there are phases between which a transition is not possible because they are protected by a certain form of symmetry. Physicists refer to these as topological phases. One example of this is the Haldane phase, named after the 2016 Nobel Prize winner in physics Duncan Haldane, which occurs in antiferromagnetic spin-1 chains.
A team of researchers at MPQ has now succeeded in realising this exotic state of matter in a simple system of ultracold atoms. Using a quantum gas microscope, they brought the atomic spins into the desired shape, measured the properties of the system and thus found the hidden internal order typical of the Haldane phase.
