Spinful topological phases in acoustic crystals with projective PT symmetry

Abstract

For the classification of topological phases of matter, an important consideration is whether a system is spinless or spinful, as these two classes have distinct symmetry algebra that gives rise to fundamentally different topological phases. However, only recently has it been realized theoretically that in the presence of gauge symmetry, the algebraic structure of symmetries can be projectively represented, which possibly enables the switch between spinless and spinful topological phases. Here, we report the first experimental demonstration of this idea by realizing spinful topological phases in "spinless" acoustic crystals with projective space-time inversion symmetry. In particular, we realize a DIII-class one-dimensional topologically gapped phase characterized by a 2Z winding number, which features Kramers degenerate bands and Kramers pair of topological boundary modes. Our work thus overcomes a fundamental constraint on topological phases by spin classes.

6 pages, 4 figures

References in corpus (23)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Photonics
• Classification of topological insulators and superconductors in three spatial dimensions
• Scheme to Achieve Silicon Topological Photonics
• Topological Acoustics
• Observation of phononic helical edge states in a mechanical 'topological insulator'
• Observation of topological valley transport of sound in sonic crystals
• Topological acoustics
• Acoustic realization of quadrupole topological insulators
• Realization of an acoustic third-order topological insulator
• $PT$ Symmetric Real Dirac Fermions and Semimetals
• Projectively enriched symmetry and topology in acoustic crystals
• Landau-Zener Transition in Topological Acoustic Pumping
• Acoustic Möbius insulators from projective symmetry
• Observation of Non-Abelian Thouless Pump
• Observation of degenerate zero-energy topological states at disclinations in an acoustic lattice
• ${\mathbb{Z}}_2$-projective translational symmetry protected topological phases
• Switching spinless and spinful topological phases with projective $PT$ symmetry
• Brillouin Klein Bottle From Artificial Gauge Fields
• The gauge-field extended $k\cdot p$ method and novel topological phases
• Unconventional quantum sound-matter interactions in spin-optomechanical-crystal hybrid systems
• Experimental observation of non-Abelian earring nodal links in phononic crystals

Cited by in corpus (11)

• Demonstration of acoustic high-order Stiefel-Whitney semimetal in bilayer graphene sonic crystals
• Hofstadter Topology with Real Space Invariants and Reentrant Projective Symmetries
• General Theory of Momentum-Space Nonsymmorphic Symmetry
• Higher-order Klein bottle topological insulator in three-dimensional acoustic crystals
• Engineering rich two-dimensional higher-order topological phases by flux and periodic driving
• Projective symmetry determined topology in flux Su-Schrieffer-Heeger model
• A new class of higher-order topological insulators that localize energy at arbitrary multiple sites
• Projective Spacetime Symmetry of Spacetime Crystals
• Brillouin Platycosms and Topological Phases
• Topological phases protected by projective space-time inversion symmetry in alkaline-earth-metal-like atoms
• Breakdown of the symmetry constraint in a Floquet topological insulator