Spin waves and quantum collective phenomena in Boltzmann gases

Bashkin, Eugene P.

doi:10.1070/pu1986v029n03abeh003179

Cited by 26 publications

(18 citation statements)

References 4 publications

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“…If the range of interaction is shorter than the DeBroglie wavelength, such excitations are also predicted [8][9][10][11][12][13] and observed 14,15 in dilute spin-polarized gases. The transverse spin-wave dynamics has been the subject of a series of theoretical investigations 12,16 .…”

Section: Introductionmentioning

confidence: 99%

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Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Morawetz

2015

Phys. Rev. B

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The spin and density response functions in the random phase approximation (RPA) are derived by linearizing the kinetic equation including a magnetic field, the spin-orbit coupling, and mean fields with respect to an external electric field. Different polarization functions appear describing various precession motions showing Rabi satellites due to an effective Zeeman field. The latter turns out to consist of the mean-field magnetization, the magnetic field, and the spin-orbit vector. The collective modes for charged and neutral systems are derived and a threefold splitting of the spin waves dependent on the polarization and spin-orbit coupling is shown. The dielectric function including spin-orbit coupling, polarization and magnetic fields is presented analytically for long wave lengths and in the static limit. The dynamical screening length as well as the long-wavelength dielectric function shows an instability in charge modes, which are interpreted as spin segregation and domain formation. The spin response describes a crossover from damped oscillatory behavior to exponentially damped behavior dependent on the polarization and collision frequency. The magnetic field causes ellipsoidal trajectories of the spin response to an external electric field and the spin-orbit coupling causes a rotation of the spin axes. The spin-dephasing times are extracted and discussed in dependence on the polarization, magnetic field, spin-orbit coupling and single-particle relaxation times.

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Section: Introductionmentioning

confidence: 99%

“…The transverse spin-wave dynamics has been the subject of a series of theoretical investigations 12,16 . In ultracold gases, spin waves have been observed, even spatially resolved 17,18 , and were described by longitudinal spin waves 19 .…”

Section: Introductionmentioning

confidence: 99%

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Morawetz

2015

Phys. Rev. B

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“…Our conclusion is nevertheless that the equivalence is perfect to first order in the scattering length a but does not hold to higher orders in a. We finally remark that, when describing a non-degenerate dilute atomic gas in terms of quasi-particles (see the work of Bashkin [16], for example), a quasi-particle is just a particle whose kinetic energy p 2 /2m is shifted by a local mean field term, so that the kinetic drift term of the quasi-particle transport equation is left unchanged.…”

Section: Discussionmentioning

confidence: 94%

“…For a discussion of the hydrodynamic-like description of spin waves in the collisionless regime of non-degenerate dilute gases, see Refs. [16,41].…”

Section: Large Non-hydrodynamic Spin Wavesmentioning

confidence: 99%

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Large amplitude spin waves in ultra-cold gases

Fuchs

Gangardt

Laloë

2003

The European Physical Journal D - Atomic, Molecular and Optical

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We discuss the theory of spin waves in non-degenerate ultra-cold gases, and compare various methods which can be used to obtain appropriate kinetic equations. We then study non-hydrodynamic situations, where the amplitude of spin waves is sufficiently large to bring the system far from local equilibrium. The full position and momentum dependence of the distribution function must then be retained.In the first part of the article, we compare two general methods which can be used to derive a kinetic equation for a dilute gas of atoms (bosons or fermions) with two internal states (treated as a pseudo-spin 1/2). The collisional methods are in the spirit of Boltzmann's original derivation of his kinetic equation where, at each point of space, the effects of all sorts of possible binary collisions are added. We discuss two different versions of collisional methods, the Yvon-Snider approach and the S matrix approach. The second method uses the notion of mean field, which modifies the drift term of the kinetic equation, in the line of the Landau theory of transport in quantum liquids. For a dilute cold gas, it turns out that all these derivations lead to the same drift terms in the transport equation, but differ in the precise expression of the collision integral and in higher order gradient terms.In the second part of the article, the kinetic equation is applied to spin waves (or internal conversion) in trapped ultra-cold gases. Numerical simulations are used to illustrate the strongly non-hydrodynamic character of the spin waves recently observed with trapped 87 Rb atoms. The decay of the phenomenon, which takes place when the system relaxes back towards equilibrium, is also discussed, with a short comment on decoherence.In two appendices we calculate the Wigner transform of the interaction term in the S matrix method, to first order in gradients; appendix I treats the case of spin-independent interactions, appendix II that of spin-dependent interactions.

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Semiquantum Gases: Quantum Collective Phenomena in Classical Temperature Range

Bashkin

1988

Condensed Matter Theories

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Spin waves and quantum collective phenomena in Boltzmann gases

Cited by 26 publications

References 4 publications

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Large amplitude spin waves in ultra-cold gases

Semiquantum Gases: Quantum Collective Phenomena in Classical Temperature Range

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