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We investigate the superfluidity of attractive Fermi gas in a square optical lattice with spin-orbit coupling (SOC). We show that the system displays a variety of new features. At half filling, SOC induces a Dirac semimetal and the system undergoes a semimetal-superfluid transition. Near half filling, we find that the superfluidity tends to be suppressed due to the emerging Dirac cones. While for small fillings, SOC can induce a BCS-BEC crossover beyond the conventional attractive Hubbard model, which is characterized by a bound state in the lattices. Moreover, we demonstrate that the superfluid density also exhibits many unusual properties in the lattices. [ABSTRACT FROM AUTHOR]

We systematically investigate the weakly trapped spin-1 Bose-Einstein condensates with spin-orbit coupling in an external Zeeman field. We find that the mean-field ground state favors either a magnetized standing-wave phase or plane-wave phase when the strength of the Zeeman field is below a critical value related to the strength of spin-orbit coupling. The Zeeman field can induce a phase transition between standing-wave and plane-wave phases, and we determine the phase boundary analytically and numerically. The magnetization of these two phases responds to the external magnetic field in a very unique manner: the linear Zeeman effect magnetizes the standing-wave phase along the direction of the magnetic field, but the quadratic Zeeman effect demagnetizes the plane-wave phase. When the strength of Zeeman field surpasses the critical value, the system is completely polarized to a ferromagnetic state or polar state with zero momentum. [ABSTRACT FROM AUTHOR]

In this Brief Report, we observed the dynamic guiding of 10-keV O- ions (50 pA/mm2) transmitting through A12O3 nanocapillaries. The transmitted O- ions shift gradually to the direction of the capillary axis, and the angular FWHM also increases significantly. However, the transmission rate of O- ions decreases. The data imply that the charges deposited in capillaries provide a sufficient guiding force to the incident O- ions. [ABSTRACT FROM AUTHOR]

We explore a way of producing the Rashba spin-orbit coupling (SOC) for ultracold atoms by using a two-component (spinor) atomic Bose-Einstein condensate (BEC) confined in a bilayer geometry. The SOC of the Rashba type is created if the atoms pick up a π phase after completing a cyclic transition between four combined spin-layer states composed of two spin and two layer states. The cyclic coupling of the spin-layer states is carried out by combining an intralayer Raman coupling and an interlayer laser assisted tunneling. We theoretically determine the ground-state phases of the spin-orbit-coupled BEC for various strengths of the atom-atom interaction and the laser-assisted coupling. It is shown that the bilayer scheme provides a diverse ground-state phase diagram. In an intermediate range of the atom-light coupling two interlacing lattices of half-skyrmions and half-antiskyrmions are spontaneously created. In the strong-coupling regime, where the SOC of the Rashba type is formed, the ground state represents plane-wave or standing-wave phases depending on the interaction between the atoms. A variational analysis is shown to be in good agreement with the numerical results. [ABSTRACT FROM AUTHOR]