Summary
What happens when a refractive-index change is faster than an optical cycle?
Experimentally drives a large, abrupt index change and studies time refraction.
Measures an enhanced frequency shift as the transition becomes faster.
Related modelling approaches
Relation labels come from the method guide and are editorial. Unlabelled links are conceptual connections or comparison methods; the paper does not necessarily implement them.
Commentary
This is a temporal-interface experiment, not a complete optical time-crystal demonstration.
Provides an experimental ingredient for temporal periodicity; Floquet theory describes the repeated-modulation problem.
Interpretation and connections in this note, separate from the authors’ reported findings.