For centuries, physics defined crystals as ordered lattices of atoms repeating an unchanging geometric pattern in three-dimensional space. However, in 2012, Nobel laureate Frank Wilczek posed a bold hypothesis: could an ordered structure exist whose pattern repeated periodically not in space, but in time?
Although the scientific community initially suspected it contradicted the laws of thermodynamics, in 2017 several laboratories succeeded in synthesizing the first time crystals. Unlike an ordinary clock, which requires a battery or winding to make its pendulum swing, these quantum systems change configuration rhythmically and infinitely while in their lowest-energy ground state, meaning without consuming energy in the process.
The secret of this behavior lies in the spontaneous breaking of time-translation symmetry:
- Subharmonic response: When stimulating a chain of ions or spins with regular electromagnetic pulses, the system responds by oscillating at a rate that is a multiple of the stimulus, setting its own internal beat.
- Immunity to noise: Even if the environment experiences thermal fluctuations or microscopic disturbances, the time crystal does not lose its quantum synchrony.
- Computational revolution: In 2021, researchers used quantum computers such as Google's Sycamore processor to keep hundreds of qubits stable in this phase, demonstrating their potential to create quantum memories ultra-resistant to decoherence.
Although they do not allow the creation of perpetual motion machines usable for extracting free energy, time crystals opened an uncharted territory in non-equilibrium condensed matter physics.
Source: Nature / Physical Review Letters
