Time crystals are a new phase of matter that break translation symmetry in time and exhibit perpetual time-dependent behavior without an external energy source.
Quantum platforms like Google's Sycamore chip offer opportunities to experimentally realize time crystals and explore new phases of quantum matter.
Deep dives
Introduction to Time Crystals
Time crystals are a unique phase of matter that exist in the quantum world. While perpetual motion machines are impossible in our classical world due to friction, time crystals challenge this impossibility by continuously changing back and forth in the quantum realm. Time crystals break translation symmetry in time and exhibit periodic time-dependent behavior forever, without the need for an external source of energy. This new phase of matter is stable, robust, and goes against the laws of equilibrium thermodynamics.
Crystal Structure and Symmetry
To understand time crystals, it's important to grasp the concept of crystals and the symmetries they break. Crystals are defined by symmetries and their breaking. In terms of translation symmetry in space, crystal structures arrange atoms in a periodic array, breaking the continuous translation symmetry. Solids like ice are crystals, while liquids and gases maintain translation symmetry. This breaking of symmetry in space distinguishes different phases of matter.
Translation Symmetry in Time
Just as crystals break translation symmetry in space, time crystals break translation symmetry in time. In our classical world, systems tend to evolve towards entropy maximizing equilibrium states, making time crystals seemingly impossible. However, in the quantum realm, and in particular, in non-equilibrium settings, time crystals can be realized. Time crystals exhibit a periodic pulsing behavior that persists forever, without any input or drain of energy.
Quantum Platforms and Time Crystal Realization
Time crystals have been experimentally realized using quantum platforms like Google's Sycamore chip. Quantum computers, while still far from being fully functional, provide a unique opportunity to explore and understand quantum matter in non-equilibrium regimes. These quantum platforms allow for controlled interactions and measurements, enabling the realization and study of time crystals and other non-equilibrium phenomena. While practical applications may not be immediately apparent, the study of time crystals pushes the boundaries of our understanding of quantum dynamics and the possibilities of new phases of matter.
A new phase of matter called a “time crystal” plays with our expectations of thermodynamics. The physicist Vedika Khemani talks with Steven Strogatz about its surprising quantum behavior.
