Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review Letters

Quadrupole spin oscillations in polarized rarefied media

Eugene P. Bashkin, Oleg L. Puzyrko

Published Apr 12, 1993• 1 citation
Publisher

Abstract

A new branch of weakly damped collective magnetic excitations in spin-polarized low-density systems is predicted. This type of wave corresponds to the transverse oscillations of the macroscopic quadrupole moment while the magnetization does not oscillate. The spectra of both spin waves and quadrupole modes are calculated. The theory can be applied to gaseous H\ensuremath{\downarrow}, D\ensuremath{\downarrow}, and other rarefied gases of S=1 particles.

DOI
10.1103/physrevlett.70.2309

Related papers

Linear spin waves in a trapped Bose gas

Tetsuro Nikuni, JAMES E. JUN. WILLIAMS, C. W. Clark

An ultracold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with ${}^{87}\mathrm{Rb}$ atoms confined in a harmonic trap. We present a theory of the spin-wave collective modes based on the moment method for trapped gases. In the collisionless and hydrodynamic limits, we derive analytic expressions for the frequencies and damping rates of modes with dipole and quadrupole symmetry. We find that the frequency for a given mode is given by a temperature-independent function of the peak density n, and falls off as $1/n.$ We also find that, to a very good approximation, excitations in the radial and axial directions are decoupled. We compare our model to the numerical integration of a one-dimensional version of the kinetic equation and find very good qualitative agreement. The damping rates, however, show the largest deviation for intermediate densities, where one expects Landau damping---which is unaccounted for in our moment approach---to play a significant role.

arXiv:cond-mat/0205450•Physical Review A•Oct 11, 2002•21 citations

Collective Spin Oscillations in Spin-Polarized Gases: Spin-Polarized Hydrogen

Laurent P. Lévy, Andrei E. Ruckenstein

The spin dynamics of weakly interacting, spin-polarized quantum gases are discussed in terms of a quasiparticle picture of these systems. Quantum mechanical exchange between identical particles introduces "molecular" magnetic fields which give rise to the precession of the spin current; this in turn leads to coherent oscillations of the magnetization. The theory is used to discuss magnetic resonance experiments in spin-polarized atomic hydrogen.

Physical Review Letters•Apr 23, 1984•87 citations

Spin rotation effects and spin waves in gaseous 3He↑

Pierre-Jean Nacher, Geneviève Tastevin, Michèle Leduc +2 more

Spin polarized gases such as H↑ or 3He↑ can propagate damped spin waves at low temperatures; their origin is the so-called « identical spin rotation effect » in collisions between identical particles. We report here the observation of such effects in 3He↑ in the temperature range 2 < T < 6 K, and preliminary measurements of the coefficient μ which characterizes the quality factor of the spin oscillations. The measurements are in agreement with the numerical calculations of C. Lhuillier.

Journal de Physique Lettres•Jan 1, 1984•71 citations

Symmetry and relaxation dynamics of spins = 1 magnets

Mikhail Yurievich Kovalevsky, Anton V. Hlushchenko

Pure and mixed quantum states of spin s = 1 magnets are examined by introducing a polarization density matrix. Uniaxial and biaxial quadrupole orderings corresponding to pure magnetic states are found and the degrees of polarization are calculated. The types of normal and degenerate magnetic states associated with subalgebras of Poisson brackets of the magnetic degrees of freedom are established. The spectra of collective magnetic excitations are calculated taking damping in the normal and degenerate states into account.

Low Temperature Physics•May 1, 2014•8 citations

Elementary excitations in dipolar spin-1 Bose-Einstein condensates

J. A. M. Huhtamäki, Pekko Kuopanportti

We have numerically solved the low-energy excitation spectra of ferromagnetic Bose-Einstein condensates subject to dipolar interparticle interactions. The system is assumed to be harmonically confined by purely optical means, thereby maintaining the spin degree of freedom of the condensate order parameter. Using a zero-temperature spin-1 model, we solve the Bogoliubov excitations for different spin textures, including a spin-vortex state in the absence of external magnetic fields and a rapidly rotating polarized spin texture in a finite homogeneous field. In particular, we consider the effect of dipolar interactions on excitations characteristic of ferromagnetic condensates. The energies of spin waves and magnetic quadrupole modes are found to increase rapidly with the dipolar coupling strength, whereas the energies of density oscillations change only slightly.

arXiv:1107.2061•Physical Review A•Oct 25, 2011•8 citations

Collective Excitations in Spin-Density-Wave Systems

A. K. Rajagopal

The collective excitations of systems which have Overhauser spin-densing-wave ground states are here investigated using a Bogolyubov transformation and the random-phase approximation. It is found that there may be transverse oscillations of the antiferromagnetic spin-wave character as well as longitudinal oscillations of the plasma type. The calculations are based on a short-range model.

Physical Review•Mar 1, 1965•13 citations
A new branch of weakly damped collective magnetic excitations in spin-polarized low-density systems is predicted. This type of wave corresponds to the transverse oscillations of the macroscopic quadrupole moment while the magnetization does not oscillate. The spectra of both spin waves and quadrupole modes are calculated. The theory can be applied to gaseous H\ensuremath{\downarrow}, D\ensuremath{\downarrow}, and other rarefied gases of S=1 particles.
An ultracold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with 87Rb{}^{87}\mathrm{Rb}87Rb atoms confined in a harmonic trap. We present a theory of the spin-wave collective modes based on the moment method for trapped gases. In the collisionless and hydrodynamic limits, we derive analytic expressions for the frequencies and damping rates of modes with dipole and quadrupole symmetry. We find that the frequency for a given mode is given by a temperature-independent function of the peak density n, and falls off as 1/n.1/n.1/n. We also find that, to a very good approximation, excitations in the radial and axial directions are decoupled. We compare our model to the numerical integration of a one-dimensional version of the kinetic equation and find very good qualitative agreement. The damping rates, however, show the largest deviation for intermediate densities, where one expects Landau damping---which is unaccounted for in our moment approach---to play a significant role.
Spin polarized gases such as H↑ or 3He↑ can propagate damped spin waves at low temperatures; their origin is the so-called « identical spin rotation effect » in collisions between identical particles. We report here the observation of such effects in 3He↑ in the temperature range 2 < T < 6 K, and preliminary measurements of the coefficient μ which characterizes the quality factor of the spin oscillations. The measurements are in agreement with the numerical calculations of C. Lhuillier.
Pure and mixed quantum states of spin s = 1 magnets are examined by introducing a polarization density matrix. Uniaxial and biaxial quadrupole orderings corresponding to pure magnetic states are found and the degrees of polarization are calculated. The types of normal and degenerate magnetic states associated with subalgebras of Poisson brackets of the magnetic degrees of freedom are established. The spectra of collective magnetic excitations are calculated taking damping in the normal and degenerate states into account.
We have numerically solved the low-energy excitation spectra of ferromagnetic Bose-Einstein condensates subject to dipolar interparticle interactions. The system is assumed to be harmonically confined by purely optical means, thereby maintaining the spin degree of freedom of the condensate order parameter. Using a zero-temperature spin-1 model, we solve the Bogoliubov excitations for different spin textures, including a spin-vortex state in the absence of external magnetic fields and a rapidly rotating polarized spin texture in a finite homogeneous field. In particular, we consider the effect of dipolar interactions on excitations characteristic of ferromagnetic condensates. The energies of spin waves and magnetic quadrupole modes are found to increase rapidly with the dipolar coupling strength, whereas the energies of density oscillations change only slightly.