Engineering Rashba Spin-Orbit Coupling for a Bose-Einstien Condensate
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Abstract
Topological order can be found in a wide range of physical systems, from crystalline solids to opto-mechanic, 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.
I will describe our engineered 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 of pi. 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.
Bio
Ian B. Spielman received his Ph.D. degree in physics from the California Institute of Technology in 2004 for studying quantum Hall bilayers. As a postdoc he spent two years at NIST, Gaithersburg (USA) studying the physics of the superfluid‐to‐insulator transition in 2D atomic Bose gases. Since 2006 he is a physicist at NIST. His research focuses on realizing Hamiltonians familiar in condensed matter physics in atomic systems, including pioneering work creating artificial gauge fields for neutral atoms.
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