Browsing by Author "Scarola, V. W."
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Item Dzyaloshinskii-Moriya Interaction and Spiral Order in Spin-Orbit Coupled Optical Lattices(Nature Publishing Group, 2015-05-27) Gong, Ming; Qian, Yinyin; Yan, Mi; Scarola, V. W.; Zhang, Chuanwei; H-3571-2011 (Zhang, C); Zhang, ChuanweiWe show that the recent experimental realization of spin-orbit coupling in ultracold atomic gases can be used to study different types of spin spiral order and resulting multiferroic effects. Spin-orbit coupling in optical lattices can give rise to the Dzyaloshinskii-Moriya (DM) spin interaction which is essential for spin spiral order. By taking into account spin-orbit coupling and an external Zeeman field, we derive an effective spin model in the Mott insulator regime at half filling and demonstrate that the DM interaction in optical lattices can be made extremely strong with realistic experimental parameters. The rich finite temperature phase diagrams of the effective spin models for fermions and bosons are obtained via classical Monte Carlo simulations.Item Emergent Kinetics and Fractionalized Charge in 1D Spin-Orbit Coupled Flatband Optical Lattices(2014-03-18) Lin, Fei; Zhang, Chuanwei; Scarola, V. W.; Zhang, ChuanweiRecent ultracold atomic gas experiments implementing synthetic spin-orbit coupling allow access to flatbands that emphasize interactions. We model spin-orbit coupled fermions in a one-dimensional flatband optical lattice. We introduce an effective Luttinger-liquid theory to show that interactions generate collective excitations with emergent kinetics and fractionalized charge, analogous to properties found in the two-dimensional fractional quantum Hall regime. Observation of these excitations would provide an important platform for exploring exotic quantum states derived solely from interactions.Item Spin-Orbit-Driven Transitions between Mott Insulators and Finite-Momentum Superfluids of Bosons in Optical Lattices(Amer Physical Soc, 2018-11-05) Yan, Mi; Qian, Yinyin; Hui, Hoi-Yin; Gong, Ming; Zhang, Chuanwei; Scarola, V. W.; 0000 0000 3722 2361 (Zhang, C); 4042455 (Zhang, C); Qian, Yinyin; Gong, Ming; Zhang, ChuanweiSynthetic spin-orbit coupling in ultracold atomic gases can be taken to extremes rarely found in solids. We study a two-dimensional Hubbard model of bosons in an optical lattice in the presence of spin-orbit coupling strong enough to drive direct transitions from Mott insulators to superfluids. Here we find phase-modulated superfluids with finite momentum that are generated entirely by spin-orbit coupling. We investigate the rich phase patterns of the superfluids, which may be directly probed using time-of-flight imaging of the spin-dependent momentum distribution.Item Superfluidity in the Absence of Kinetics in Spin-Orbit-Coupled Optical Lattices(Amer Physical Soc) Hui, Hoi-Yin; Zhang, Yongping; Zhang, Chuanwei; Scarola, V. W.; 0000 0000 3722 2361 (Zhang, C); 4042455 (Zhang, C); Zhang, ChuanweiAt low temperatures bosons typically condense to minimize their single-particle kinetic energy while interactions stabilize superfluidity. Optical lattices with artificial spin-orbit coupling challenge this paradigm, because here kinetic energy can be quenched in an extreme regime where the single-particle band flattens. To probe the fate of superfluidity in the absence of kinetics we construct and numerically solve interaction-only tight-binding models in flatbands. We find that superfluid states arise entirely from interactions operating in quenched kinetic energy bands, thus revealing a distinct and unexpected condensation mechanism. Our results have important implications for the identification of quantum condensed phases of ultracold bosons beyond conventional paradigms.