arXiv:1902.00634 · Physical Review A

Bloch oscillations of spin-orbit-coupled cold atoms in an optical lattice and spin-current generation

Wei Ji, Keye Zhang, Weiping Zhang, Lu Zhou

Published Feb 1, 2019• 17 citations

Abstract

We study the Bloch oscillation dynamics of a spin-orbit-coupled cold atomic gas trapped inside a one-dimensional optical lattice. The eigenspectra of the system is identified as two interpenetrating Wannier-Stark ladders. Based on that, we carefully analyzed the Bloch oscillation dynamics and found out that intraladder coupling between neighboring rungs of the Wannier-Stark ladder give rise to ordinary Bloch oscillation, while interladder coupling leads to small-amplitude high-frequency oscillation superimposed on it. Specifically, spin-orbit interaction breaks Galilean invariance, which can be reflected by out-of-phase oscillation of the two spin components in the accelerated frame. The possibilities of generating spin current in this system are also explored.

DOI: 10.1103/physreva.99.023604

Related papers

Bloch Oscillations in Optical and Zeeman Lattices in the Presence of Spin-Orbit Coupling

Yaroslav V. Kartashov, V. V. Konotop, Dmitry A. Zezyulin +1 more

We address Bloch oscillations of a spin-orbit coupled atom in periodic potentials of two types: optical and Zeeman lattices. We show that in optical lattices the spin-orbit coupling allows controlling the direction of atomic motion and may lead to complete suppression of the oscillations at specific values of the coupling strength. In Zeeman lattices the energy bands are found to cross each other at the boundaries of the Brillouin zone, resulting in period doubling of the oscillations. In all cases, the oscillations are accompanied by rotation of the pseudospin, with a dynamics that is determined by the strength of the spin-orbit coupling. The predicted effects are discussed also in terms of a Wannier-Stark ladder, which in optical lattices consist of two mutually shifted equidistant subladders.

arXiv:1610.04716Physical Review LettersNov 18, 201667 citations

Chiral Bloch–Zener oscillations of spin–orbit coupled cold atoms in an optical superlattice

Z. B. Li, Lu Zhou, Yan Li

Abstract We study the Bloch oscillation (BO) dynamics of spin–orbit coupled cold atoms in a one-dimensional Su–Schrieffer–Heeger optical lattice. The Hamiltonian of our system can be mapped into a tilted SSH ladder pierced by an effective magnetic flux. Based on the calculation of Wannier–Stark states, we investigate dynamical properties of BOs with the chiral character of spin-momentum locking. Importantly, the chiral Bloch–Zener oscillations can be induced by adjusting system parameters. The corresponding Landau–Zener (LZ) tunneling probability is analytically derived by the LZ model and we found a good agreement with the numerical simulation.

Journal of Physics B Atomic Molecular and Optical PhysicsJan 5, 20213 citations

Spin-orbit-coupled Bose-Einstein condensate in a tilted optical lattice

Jonas Larson, J.-P. Martikainen, Anssi Collin +1 more

Bloch oscillations appear for a particle in a weakly tilted periodic potential. The intrinsic spin Hall effect is an outcome of a spin-orbit coupling. We demonstrate that both of these phenomena can be realized simultaneously in a gas of weakly interacting ultracold atoms exposed to a tilted optical lattice and to a set of spatially dependent light fields inducing an effective spin-orbit coupling. It is found that both the spin Hall and the Bloch oscillation effects may coexist, showing, however, a strong correlation between the two. These correlations are manifested as a transverse spin current oscillating in-phase with the Bloch oscillations. On top of the oscillations originating from the periodicity of the model, a trembling motion is found which is believed to be atomic Zitterbewegung. It is argued that the damping of these Zitterbewegung oscillations may to a large extent be prevented in the present setup considering a periodic optical lattice potential.

arXiv:1001.2527Physical Review AOct 25, 201054 citations

Quasi-periodic Wannier–Stark ladders from driven atomic Bloch oscillations

M. Artoni, Giuseppe Carlo La Rocca, G. Ferrari

Periodic Wannier–Stark ladder structures of the energy resonances associated with Bloch oscillations can be readily modified into quasi-periodic ones that exhibit peculiar self-similar effects. A compact theoretical description of the dynamics of driven Bloch oscillations is developed here within the quasi-momentum representation. We identify a rather viable scheme based on ultracold atomic wavepackets subject to gravity in a driven optical lattice potential where a self-similar scaling could be observed. Its feasibility in terms of realistic experimental parameters is also discussed.

Proceedings of the Royal Society A Mathematical Physical and Engineering SciencesSep 10, 20140 citations

The Bloch oscillations of spin-orbit coupled Bose-Einstein condensates in deep optical lattices

Yanchao Zhang, Chen Jiao, Ai‐Xia Zhang +1 more

Abstract We study the ground state and the Bloch oscillations of the spin-orbit coupled Bose-Einstein condensates in one-dimensional deep optical lattices. The phase transition between the zero-momentum phase and the plane-wave phase in untilted deep optical lattices is studied analytically. The Bloch oscillations in tilted lattices started in different ground state phases are analyzed. It is found that the Bloch dynamics is harmonic (anharmonic) in the zero-momentum phase (plane-wave phase). Furthermore, the modification of the Bloch oscillations induced by spin-orbit coupling, tunnelling coefficient and the external force (the inclination of the tilt) is revealed. In addition, the analytical condition for emerging the long-lived Bloch oscillations is obtained and the corresponding diagram in parameter space is provided. Particularly, we find that the spin-orbit coupling can extend the duration of the Bloch oscillations in the plane-wave phase. We provide an effective method to manipulate the Bloch dynamics in the deep optical lattices.

Europhysics Letters (EPL)May 23, 20223 citations

Observation of the Wannier-Stark fan and the fractional ladder in an accelerating optical lattice

Kirk W. Madison, Martin C. Fischer, Mark G. Raizen

We report an experimental study of the Wannier-Stark fan and the fractional Wannier-Stark ladder using laser-cooled sodium atoms in an accelerating one-dimensional standing wave of light. We prepare the atoms in the lowest motional band of the optical lattice and then impose a constant acceleration. A weak oscillatory component is added to the acceleration in order to resonantly drive interband transitions, and the number of atoms that remain in the lowest band is measured as a function of the probe frequency. The spectrum is characterized by a ladder of resonances spaced by the atomic Bloch oscillation frequency ${\ensuremath{\omega}}_{B}.$ When an additional, strong ac component at frequency $\ensuremath{\Omega}$ is added, a fractional ladder is observed with a spacing related to the electric matching ratio $\ensuremath{\Omega}/{\ensuremath{\omega}}_{B}.$

Physical Review ASep 1, 199938 citations