Browsing by Author "Zheng, Zhen"
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Item Artificial topological models based on a one-dimensional spin-dependent optical lattice(American Physical Society, 2017) Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan; Rice Center for Quantum MaterialsTopological matter is a popular topic in both condensed matter and cold-atom research. In the past decades, a variety of models have been identified with fascinating topological features. Some, but not all, of the models can be found in materials. As a fully controllable system, cold atoms trapped in optical lattices provide an ideal platform to simulate and realize these topological models. Here we present a proposal for synthesizing topological models in cold atoms based on a one-dimensional spin-dependent optical lattice potential. In our system, features such as staggered tunneling, staggered Zeeman field, nearest-neighbor interaction, beyond-near-neighbor tunneling, etc. can be readily realized. They underlie the emergence of various topological phases. Our proposal can be realized with current technology and hence has potential applications in quantum simulation of topological matter.Item Effective p-wave interaction and topological superfluids in s-wave quantum gases(American Physical Society, 2016) Wang, Bin; Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan; Rice Center for Quantum Materialsp-wave interaction in cold atoms may give rise to exotic topological superfluids. However, the realization of p-wave interaction in a cold atom system is experimentally challenging. Here we propose a simple scheme to synthesize effective p-wave interaction in conventional s-wave interacting quantum gases. The key idea is to load atoms into a spin-dependent optical lattice potential. Using two concrete examples involving spin-1/2 fermions, we show how the original system can be mapped into a model describing spinless fermions with nearest-neighbor p-wave interaction, whose ground state can be a topological superfluid that supports Majorana fermions under proper conditions. Our proposal has the advantage that it does not require spin-orbit coupling or loading atoms onto higher orbitals, which is the key in earlier proposals to synthesize effective p-wave interaction in s-wave quantum gases, and may provide a completely new route for realizing p-wave topological superfluids.Item Thermodynamic properties of Rashba spin-orbit-coupled Fermi gas(American Physical Society, 2014) Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan; Rice Quantum InstituteWe investigate the thermodynamic properties of a superfluid Fermi gas subject to Rashba spin-orbit coupling and effective Zeeman field. We adopt a T-matrix scheme that takes beyond-mean-field effects, which are important for strongly interacting systems, into account. We focus on the calculation of two important quantities: the superfluid transition temperature and the isothermal compressibility. Our calculation shows very distinct influences of the out-of-plane and the in-plane Zeeman fields on the Fermi gas. We also confirm that the in-plane Zeeman field induces a Fulde-Ferrell superfluid below the critical temperature and an exotic finite-momentum pseudogap phase above the critical temperature.