Spin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate

Year: 2019

Authors: Li CH., Qu CL., Niffenegger RJ., Wang SJ., He MY., Blasing DB., Olson AJ., Greene CH., Lyanda-Geller Y., Zhou Q., Zhang CW., Chen YP.

Autors Affiliation: Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47907 USA; Univ Texas Dallas, Dept Phys, Richardson, TX 75080 USA; Univ Trento, INO CNR BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, I-38123 Povo, Italy; Univ Colorado, JILA, Boulder, CO 80309 USA; Univ Colorado, Dept Phys, Boulder, CO 80309 USA; Purdue Univ, Dept Phys & Astron, W Lafayette, IN 47907 USA; Hong Kong Univ Sci & Technol, Dept Phys, Clear Water Bay, Hong Kong, Peoples R China; Purdue Univ, Purdue Quantum Ctr, W Lafayette, IN 47907 USA; MIT, Lincoln Lab, 244 Wood St, Lexington, MA 02421 USA; Kansas State Univ, Dept Phys, JR Macdonald Lab, Cardwell Hall, Manhattan, KS 66506 USA.

Abstract: Understanding the effects of spin-orbit coupling (SOC) and many-body interactions on spin transport is important in condensed matter physics and spintronics. This topic has been intensively studied for spin carriers such as electrons but barely explored for charge-neutral bosonic quasiparticles (including their condensates), which hold promises for coherent spin transport over macroscopic distances. Here, we explore the effects of synthetic SOC (induced by optical Raman coupling) and atomic interactions on the spin transport in an atomic Bose-Einstein condensate (BEC), where the spin-dipole mode (SDM, actuated by quenching the Raman coupling) of two interacting spin components constitutes an alternating spin current. We experimentally observe that SOC significantly enhances the SDM damping while reducing the thermalization (the reduction of the condensate fraction). We also observe generation of BEC collective excitations such as shape oscillations. Our theory reveals that the SOC-modified interference, immiscibility, and interaction between the spin components can play crucial roles in spin transport.

Journal/Review: NATURE COMMUNICATIONS

Volume: 10      Pages from: 375-1  to: 375-14

More Information: We thank Hui Zhai for helpful discussions and Ting-Wei Hsu for his help in experiments. This work has been supported in part by the Purdue University OVPR Research Incentive Grant and the NSF grant PHY-1708134. D.B.B. also acknowledges support by the Purdue Research Foundation Ph.D. fellowship. C.Q. and C.Z. are supported by NSF (PHY-1505496, PHY-1806227), ARO (W911NF-17-1-0128), and AFOSR (FA9550-16-1-0387). M.H. and Q.Z. acknowledge support from Hong Kong Research Council through CRF C6026-16W and start up funds from Purdue University. S.J.W. and C.H.G. are supported by NSF grant PHY-1607180. Y.L.-G. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award DE-SC0010544.
KeyWords: Collective Excitations; Room-temperature; Coulomb Drag; Dynamics; Oscillations; Spintronics; Transport; Matter; Phase
DOI: 10.1038/s41467-018-08119-4

Citations: 25
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