Time crystal

A time crystal is a kind of quantum system.  
It changes in a repeating way over time, even when it is in its lowest-energy state (the ground state).  
It does this without taking in energy from outside.

An ordinary crystal has atoms in a pattern that repeats in space.  
A time crystal has a pattern that repeats in time.

 History 
 2012: Nobel Prize winner Frank Wilczek first suggested the idea.  
 2017: Chris Monroe and his team found signs of time-crystal behaviour in chains of ytterbium ions.  
 2021: Scientists made the first video of a time crystal.  
 2024: Scientists at the Technical University of Dortmund said they built a time crystal that lasted for forty minutes.  

 Possible uses 
Time crystals may one day be used as quantum memory.

 In fiction 
Writers of science fiction sometimes use the name "time crystal" for imaginary objects.  
These are not the same as real time crystals.

 See also 
 Quantum entanglement

 References 

Category:Quantum mechanics
Category:States of matter