A time crystal is a phase of a matter which is ordered in time, similar to classical crystals which are ordered spatially. In other words, the structure of a time crystal is ever-changing but with some period. In fact, time crystals are quantum systems whose ground states are characterized by periodic motion (so-called non-equilibrium matter), e.g. periodically changing spins in a chain of ions. See more for example here and on Wiki.
Time crystals were proposed in 2012 by Frank Wilczek as a theoretical concept, however, later their existence was proved (see e.g. references on Wiki page). In July 2021, Google claimed that its team prepared the time crystal on Sycamore processor, see the paper Observation of Time-Crystalline Eigenstate Order on a Quantum Processor.
In many articles on time crystals, I see a statement that time crystals can help to design quantum memories (qRAM) and on this forum e.g. here. I can imagine that the periodic time change can help somehow increase decoherence times which are low in current qRAMs. However, I was not able to find any details on how time crystals can actually help in qRAM design. Could anybody shed more light on this?
Additional question to Google's claim - did they really prepare the time crystal or rather did they simulate a quantum system behaving like the time crystal?
