Universal behavior is a central property of phase transitions, which can be seen, for example, in magnets that are no longer magnetic above a certain temperature. A team of researchers from Kaiserslautern, Berlin and Hainan, China, has succeeded for the first time in observing such universal behavior in the temporal development of an open quantum system, a single cesium atom in a bath of rubidium atoms.
This finding helps to understand how quantum systems reach equilibrium. This is of interest to the development of quantum technologies, for example. The study has been published in Nature Communications.
Phase transitions in chemistry and physics are changes in the state of a substance, for example, the change from a liquid to a gaseous phase, when an external parameter such as temperature or pressure is changed.
"Magnets are a good example," says Professor Dr. Artur Widera, who heads the Individual Quantum Systems unit at University Kaiserslautern-Landau (RPTU).
"Ferromagnets show spontaneous magnetization without an external magnetic field, i.e. they are inherently magnetic, but only below a certain critical temperature. When the temperature rises above this point, the system undergoes a continuous phase transition; above this temperature, the material is no longer magnetic."
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