There we have in the mint what a crystal is. At school we learned that, from grains of sugar to diamonds, these materials share a homogeneous and orderly arrangement of their atoms, forming a pattern that repeats throughout space, giving rise to their beautiful and regular shapes. During a class at the Massachusetts Institute of Technology (MIT) where Professor Frank Wilczek, Nobel Prize in Physics, had an idea: what if there were some 'time crystals' whose structure, instead of repeating itself in space, repeated itself in time?
This 'exotic' hypothesis planted in 2012 generated a strong debate in the scientific community for years. If possible, this type of crystal must be able to maintain its stability but, at the same time, also change its crystal structure periodically; It is decided that if we observe them at different times, we should perceive that their structure (in space) is not always the same, being in a state of perpetual motion, even in a state of minimum energy or ground state.
All this directly undermines the laws of thermodynamics. And these crystals would be neither solid nor liquid nor gas. Not even plasma -ionized gas-. It would be a different state of matter.
After fierce debates in which Wilczek was branded almost crazy, in 2016 a team finally managed to show that it was theoretically possible to create time crystals, a feat that was achieved just a year later. Since then, this field of physics has become a very promising field that could revolutionize everything from quantum technology to telecommunications, through mining or the very understanding of the universe.
However, there is a problem: these crystals only appear in very particular conditions. In concrete terms, the scientists used Bose-Einstein magnon quasiparticle condensates, a state of matter that is created when particles, called bosons, are cooled to near absolute zero (-273,15 degrees Celsius or -460 degrees Fahrenheit). This requires very sophisticated equipment and, of course, cannot leave the laboratories and vacuum chambers, since the interaction with the external environment makes its creation impossible.
Until now. A team from the University of California Riverside has managed to create optical time crystals that can be generated at room temperature, as explained in a study in the journal 'Nature Communications'. To do this, a tiny micro-resonator was taken - a disc made of magnesium fluoride glass of only one millimeter in diameter that entered resonance when receiving waves of certain frequencies. They then bombarded this optical micro-resonator with beams from two lasers.
The subharmonic peaks
The subharmonic spikes (solitons), or frequency tones between the two laser beams, which indicate the breaking of time symmetry and thus created time crystals. The system creates a rotating lattice trap for optical solitons in which their periodicity or structure in time is then displayed.
To maintain the integrity of the system at room temperature, the team will use the autoinjector block, a technique that guarantees that the saline laser maintains a certain optical frequency. This means the system can be taken out of the lab and used for field applications, specifically for measuring time, integrating into quantum computers, or studying the state itself.
“When your experimental system has an energy exchange with its surroundings, dissipation and noise work hand in hand to destroy temporal order,” Hossein Taheri, Marlan and Rosemary Bourns professor of electrical and computer engineering at the UC Riverside and lead author of the study. "On our photonics platform, the system strikes a balance between gain and loss to create and preserve time crystals."
