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arXiv · 2201.03577

Topological space-time crystal

Yang Peng
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Abstract

We introduce a new class of out-of-equilibrium noninteracting topological phases, the topological space-time crystals. These are time-dependent quantum systems which do not have discrete spatial translation symmetries, but instead are invariant under discrete space-time translations. Similar to the Floquet-Bloch systems, the space-time crystals can be described by a frequency-domain-enlarged Hamiltonian, which is used to classify topologically distinct space-time crystals. We show that these space-time crystals can be engineered from conventional crystals with an additional time-dependent drive that behaves like a traveling wave moving across the crystal. Interestingly, we are able to construct 1D and 2D examples of topological space-time crystals based on tight-binding models which involve only one orbital, in contrast to the two-orbital minimal models for any previous discovered static or Floquet topological phases with crystalline structures.

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Yang Peng. 2022-01-10. Topological space-time crystal. https://doi.org/10.1103/physrevlett.128.186802

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