Greg Borzo in Phys.org:
The findings, published in the Nov. 4 issue of Science, provide the first clear demonstration of the Kibble-Zurek mechanism for a quantum phase transition in both space and time. Prof. Cheng Chin and his team of UChicago physicists observed the transition in gaseous cesium atoms at temperatures near absolute zero.
In a phase transition, matter changes its form and properties as in transitions from solid to liquid (for example, ice to water) or from liquid to gas (for example, water to steam). Those are known as first-order phase transitions.
A continuous phase transition, or second-order transition, forms defects—such as domain walls, cosmic strings and textures—where some of the matter is stuck between regions in distinct states. The Kibble-Zurek mechanism predicts how such defects and complex structures will form in space and time when a physical system goes through a continuous phase transition. Examples of continuous phase transitions include the spontaneous symmetry breaking in the early universe and, in the case of the experiment by Chin's team, a ferromagnetic phase transition in gaseous cesium atoms.
More here.