To achieve the ultra-fast changes needed, they hit the metamaterial with powerful laser pulses. This violently accelerated the material’s free-floating electrons, dynamically altering their energy and making their “effective mass” shift by up to 80% of their rest mass in fractions of a trillionth of a second. This massive, rapid shift forced the material into a time-crystal state.

A plasmonic metamaterial driven at terahertz frequencies achieves strong, ultrafast temporal modulation and shows a transition to the photonic time crystal regime with reduced plasmonic losses.