Quantum enhancement of spin drag in a Bose gas

Koller, Sonja; Groot, Adrien E.; Bons, Pieter; Duine, R. A.; Stoof, H. T. C.; Straten, P. van der

doi:10.1088/1367-2630/17/11/113026

Cited by 13 publications

(15 citation statements)

References 25 publications

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“…Finally, the above-described situation concerning magnons in a spinor gas is also different from the binary-mixture situation. There, longitudinal spin kinetics is comparable to the incoherent dynamics of the scalar fields, and hence longitudinal spin currents relax in milliseconds as well [74,75].…”

Section: E Incoherent Dynamicsmentioning

confidence: 99%

Superfluidity and spin superfluidity in spinor Bose gases

Armaitis

Duine

2017

Phys. Rev. A

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We show that spinor Bose gases subject to a quadratic Zeeman effect exhibit coexisting superfluidity and spin superfluidity, and study the interplay between these two distinct types of superfluidity. To illustrate that the basic principles governing these two types of superfluidity are the same, we describe the magnetization and particle-density dynamics in a single hydrodynamic framework. In this description spin and mass supercurrents are driven by their respective chemical potential gradients. As an application, we propose an experimentally-accessible stationary state, where the two types of supercurrents counterflow and cancel each other, thus resulting in no mass transport. Furthermore, we propose a straightforward setup to probe spin superfluidity by measuring the in-plane magnetization angle of the whole cloud of atoms. We verify the robustness of these findings by evaluating the four-magnon collision time, and find that the timescale for coherent (superfluid) dynamics is separated from that of the slower incoherent dynamics by one order of magnitude. Comparing the atom and magnon kinetics reveals that while the former can be hydrodynamic, the latter is typically collisionless under most experimental conditions. This implies that, while our zero-temperature hydrodynamic equations are a valid description of spin transport in Bose gases, a hydrodynamic description that treats both mass and spin transport at finite temperatures may not be readily feasible.

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Section: E Incoherent Dynamicsmentioning

confidence: 99%

Superfluidity and spin superfluidity in spinor Bose gases

Armaitis

Duine

2017

Phys. Rev. A

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“…From power counting, C nm ∝ dp p 7+2n+2m , we expect that C 00 < C 01 < C 11 ; hence, C 01 /C 00 C 11 1 and C 00 /C 11 1. Thus, to leading order in the ratios C 01 /C 00 C 11 and C 00 /C 11 , the spin conductivity is given by …”

Section: Angular Integrationsmentioning

confidence: 99%

“…Even for this stationary gas, without any spin polarization, a pure spin current can be established in response to opposite forces on each spin, i.e., a spin force, due to interspin scattering that transfer momentum between opposite spins. This viscosity between spins is called spin drag and has been calculated and measured in Bose and Fermi gases [9][10][11][12], and its contribution to the spin diffusion coefficient for electrons, called spin Coulomb drag, has been measured in GaAs quantum wells [13]. Due to the Peltier effect, this spin current is accompanied by a spin-heat current, a difference in the heat currents carried by each spin.…”

Section: Introductionmentioning

confidence: 99%

Spin-heat relaxation and thermospin diffusion in atomic Bose and Fermi gases

2015

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We study spin-dependent heat transport in quantum gases, focusing on transport phenomena related to pure spin currents and spin-dependent temperatures. Using the Boltzmann equation, we compute the coupled spin-heat transport coefficients as a function of temperature and interaction strength for energy-dependent s-wave scattering. We address the issue of whether spin-dependent temperatures can be sustained on a time and length scale relevant for experiments by computing the spin-heat relaxation time and diffusion length. We find that the time scale for spin-heat relaxation time diverges at low temperatures for both bosons and fermions, indicating that the concept of spin-heat accumulation is well defined for degenerate gases. For bosons, we find power-law behavior on approach to Bose condensation above the critical temperature, as expected from the theory of dynamical critical phenomena.

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“…Other promising avenues of research include a more careful account of interactions, especially with the Bose-Einstein condensation in mind, and also considering the kinetic effects in this system, e.g., the relaxation of spin current also known as spin drag [111], which was not considered here. …”

Section: Summary and Future Workmentioning

confidence: 99%

Omnidirectional spin Hall effect in a Weyl spin-orbit-coupled atomic gas

2017

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We show that in the presence of a three-dimensional (Weyl) spin-orbit coupling, a transverse spin current is generated in response to either a constant spin-independent force or a time-dependent Zeeman field in an arbitrary direction. This effect is the non-Abelian counterpart of the universal intrinsic spin Hall effect characteristic to the two-dimensional Rashba spin-orbit coupling. We quantify the strength of such an omnidirectional spin Hall effect by calculating the corresponding conductivity for fermions and non-condensed bosons. The absence of any kind of disorder in ultracold-atom systems makes the observation of this effect viable.

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Quantum enhancement of spin drag in a Bose gas

Cited by 13 publications

References 25 publications

Superfluidity and spin superfluidity in spinor Bose gases

Superfluidity and spin superfluidity in spinor Bose gases

Spin-heat relaxation and thermospin diffusion in atomic Bose and Fermi gases

Omnidirectional spin Hall effect in a Weyl spin-orbit-coupled atomic gas

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