Crystals, such as salt, sugar and ice, have a self-repeating structure in space and are very common in everyday life. Time crystals have a self-repeating structure in time and have only recently been made for the first time in materials that consist of a large number of small magnets. Utrecht researchers have for the first time succeeded in combining these two types of crystals in a droplet of sodium atoms that has been cooled down to the almost absolute zero of temperature. The researchers are publishing their results today in Physical Review Letters.
At such a low temperature, the droplet forms a so-called superfluid in which the atoms can move without experiencing friction. This prevents the space-time crystal from melting and ensures that it can exist for a long time. Since the researchers use a non-magnetic fluid, the work shows that space-time crystals can not only occur in magnetic materials. In addition, the work is of fundamental importance for the study of new phases of matter and may eventually lead to the creation of so-called atomic lasers with unusual temporal properties.
Observation of a Space-Time Crystal in a Superfluid Quantum Gas
J. Smits, L. Liao, H. T. C. Stoof, and P. van der Straten
Physical Review Letters, 2018, Editor’s suggestion