Title | Topological features without a lattice in Rashba spin-orbit coupled atoms |
Publication Type | Journal Article |
Year of Publication | 2021 |
Authors | A.. Valdes-Curiel, D.. Trypogeorgos, Q.. - Y. Liang, R.. P. Anderson, and I.. B. Spielman |
Journal | Nat. Commun. |
Volume | 12 |
Date Published | jan |
ISSN | 2041-1723 |
Abstract | Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical current, light, and atmospheric disturbances. These topological effects are quantified in terms of integer-valued `invariants', such as the Chern number, applicable to the quantum Hall effect, or the Z2 invariant suitable for topological insulators. Here, we report the engineering of Rashba spin-orbit coupling for a cold atomic gas giving non-trivial topology, without the underlying crystalline structure that conventionally yields integer Chern numbers. We validated our procedure by spectroscopically measuring both branches of the Rashba dispersion relation which touch at a single Dirac point. We then measured the quantum geometry underlying the dispersion relation using matter-wave interferometry to implement a form of quantum state tomography, giving a Berry's phase with magnitude . This implies that opening a gap at the Dirac point would give two dispersions (bands) each with half-integer Chern number, potentially implying new forms of topological transport.Here, the authors study topology in spin-orbit coupled 87Rb atoms by using time domain spectroscopy and quantum state tomography. They measure full quantum state to extract the Berry phase of the system and show signatures of a half-integer Chern index. |
DOI | 10.1038/s41467-020-20762-4 |