Observation of period-doubling Bloch oscillations

Abstract

Bloch oscillations refer to the periodic oscillation of a wavepacket in a lattice under a constant force. Typically, the oscillation has a fundamental period that corresponds to the wavepacket traversing the first Brillouin zone once. Here we demonstrate, both theoretically and experimentally, the optical Bloch oscillations where the wavepacket must traverse the first Brillouin zone twice to complete a full cycle, resulting in a period of oscillation that is two times longer than that of usual Bloch oscillations. The unusual Bloch oscillations arise due to the band crossing of valley-Hall topological edge states at the Brillouin boundary for zigzag domain walls between two staggered honeycomb lattices with inverted on-site energy detuning, which are protected by the glide-reflection symmetry of the underlying structures. Our work sheds light on the direct detection of band crossings resulting from intrinsic symmetries that extend beyond the fundamental translational symmetry in topological systems.

4 pages, 4 figures, to appear in Phys. Rev. Lett

References in corpus (9)

• Topological Photonics
• Measuring the Chern number of Hofstadter bands with ultracold bosonic atoms
• Strongly Correlated Quantum Walks in Optical Lattices
• Fractional Bloch oscillations in photonic lattices
• Observation of Bloch oscillations in complex PT-symmetric photonic lattices
• Bloch Oscillations in Optical and Zeeman Lattices in the Presence of Spin-Orbit Coupling
• Topological flat Wannier-Stark bands
• Wannier-Stark states and Bloch oscillations in the honeycomb lattice
• Bloch oscillations of topological edge modes