Topology of the Rashba model (Experiment) and quantum gases with weak measurement and classical feedback (Theory)

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Ian Spielman / JQI, NIST, University of Maryland
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Event Details & Abstracts

(1) We experimentally realized Rashba spin–orbit with 87-Rb in the F=1 ground state manifold by Raman coupling three `synthetic clocks states’ generated by a continuous dynamical decoupling scheme.  We use Fourier transform spectroscopy to directly reveal the Dirac point and construct a three-arm Ramsey interferometer to read out the associated singular Berrys curvature.  Because this realization minimizes all inelastic collisional processes and is first-order insensitive to external magnetic fields, it makes an ideal stepping off point for studying the physics of strongly interacting bosons with 2D SOC. (2) Weakly measuring many-body systems and allowing for feedback in real-time may simultaneously create and measure new phenomena in strongly correlated quantum systems. We study the dynamics of continuously measured one- and two-component Bose-Einstein condensate (BEC). Each weakly measured system yields a measurement record from which we extract real-time dynamics. We show that suitable feedback can maintain the system at ultra-low temperatures, while adding spin-dependent feedback can drive transitions between easy-axis and easy-plane ferromagnetism