Space-Time Crystal

The source dossier uses space-time crystal (STC) for systems in which translational symmetry is broken in both space and time. The term appears in the magnon experiment at the Max Planck Institute for Intelligent Systems and in the two liquid-crystal patent applications, where it is used for both discrete and continuous cases.

Magnon space–time crystal (2021)

The dossier reproduces the abstract of Phys. Rev. Lett. 126, 057201, "Real-Space Observation of Magnon Interaction with Driven Space-Time Crystals," by Nick Träger and co-authors. The abstract states that the concept of space–time crystals — translational symmetry breaking in time and space — was recently proposed and experimentally demonstrated for quantum systems, and that this work transfers the concept to magnons, demonstrating a driven STC at room temperature.

The STC is realized by strong homogeneous microwave pumping of a micron-sized permalloy (Py) stripe and is directly imaged by scanning transmission X-ray microscopy (STXM). Micromagnetic simulations were adapted to model the experimental findings. Beyond generating the STC, the authors observed the formation of a magnonic band structure due to back-folding of modes at the STC's Brillouin zone boundaries, and interactions of magnons with the STC appearing as lattice scattering, generating ultrashort spin waves down to 100-nm wavelengths that cannot be described by classical dispersion relations for linear spin-wave excitation.

The Max Planck press release adds that the German–Polish collaboration involved the Max Planck Institute for Intelligent Systems in Stuttgart, Adam Mickiewicz University and the Polish Academy of Sciences in Poznań, with imaging on the Maxymus microscope at BESSY II. The press release states that the recurring pattern formed before the two converging waves could meet and interfere, and that the pattern, which regularly disappears and reappears on its own, "must therefore be a quantum effect."

Liquid-crystal space–time crystals (patents)

The dossier reproduces excerpts from two PCT applications:

• wo2026174186 — "Discrete Space-Time Crystal Device and Method of Forming Same," claiming classical discrete space–time crystals in a chiral nematic liquid crystal driven by a Floquet electrical signal, with 1+1D and 2+1D DSTCs and period doubling relative to the drive.
• wo2026183497 — "Continuous Space-Time Crystal Device and Method of Forming and Using Same," claiming continuous space–time crystals in a nematic liquid crystal with a photo-responsive dye layer, driven by light, with claimed 0+1D, 1+1D, 2+1D and 3+1D behavior.

These are patent assertions, not independent validation, and describe a classical (soft-matter) regime distinct from the quantum time crystals of Wilczek's original proposal. The dossier does not adjudicate whether the two are the same phenomenon.

Related work

• Time Crystal — the parent concept.
• Discrete Time Crystal (DTC) and Continuous Time Crystal (CTC) — the two symmetry-breaking regimes.
• Magnon (Spin Wave Quasiparticle) — the quasiparticle forming the Max Planck STC.