Hidden-symmetry-protected Z_2 topological insulator in a cubic lattice

Abstract

Usually $Z_2$ topological insulators are protected by time reversal symmetry. Here, we present a new type of $Z_2$ topological insulators in a cubic lattice which is protected by a novel hidden symmetry, while time reversal symmetry is broken. The hidden symmetry has a composite antiunitary operator consisting of fractional translation, complex conjugation, sublattice exchange, and local gauge transformation. Based on the hidden symmetry, we define the hidden-symmetry polarization and $Z_2$ topological invariant to characterize the topological insulators. The surface states have band structures with odd number of Dirac cones, where pseudospin-momentum locking occurs. When the hidden-symmetry-breaking perturbations are added on the boundaries, a gap opens in the surface band structure, which confirms that the topological insulator and the surface states are protected by the hidden symmetry. We aslo discuss the realization and detection of this new kind of $Z_2$ topological insulator in optical lattices with ultracold atom techniques.

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Cited by in corpus (4)

• Long-range hopping and indexing assumption in one-dimensional topological insulators
• Duality,Hidden Symmetry and Dynamic Isomerism in 2D Hinge Structures
• Protection of all nondefective twofold degeneracies by anti-unitary symmetries in non-Hermitian systems
• Tunable zero modes and quantum interferences in flat-band topological insulators