Mixtures of Bose liquids at finite temperature

Colson, W.B.; Fetter, Alexander L.

doi:10.1007/bf00114996

Cited by 62 publications

(77 citation statements)

References 5 publications

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“…For the simplest case of two uniform BECs in a box, if g 2 12 > g 1 g 2 , the two components are immiscible and separate into nonoverlapping phases. Otherwise, if g 2 12 < g 1 g 2 , they form two uniform interpenetrating BECs [in the context of dilute BECs, this result apparently was first obtained by Nepomnyashchi (1974); see also (Colson and Fetter, 1978)]. …”

Section: Vortex Behavior In Two-component Bec Mixtures (Jila)mentioning

confidence: 89%

Rotating trapped Bose-Einstein condensates

2008

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After reviewing the ideal Bose-Einstein gas in a box and in a harmonic trap, I discuss the effect of interactions on the formation of a Bose-Einstein condensate (BEC), along with the dynamics of small-amplitude perturbations (the Bogoliubov equations). When the condensate rotates with angular velocity Ω, one or several vortices nucleate, with many observable consequences. With more rapid rotation, the vortices form a dense triangular array, and the collective behavior of these vortices has additional experimental implications. For Ω near the radial trap frequency ω ⊥ , the lowest-Landau-level approximation becomes applicable, providing a simple picture of such rapidly rotating condensates. Eventually, as Ω → ω ⊥ , the rotating dilute gas is expected to undergo a quantum phase transition from a superfluid to various highly correlated (nonsuperfluid) states analogous to those familiar from the fractional quantum Hall effect for electrons in a strong perpendicular magnetic field.

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Section: Vortex Behavior In Two-component Bec Mixtures (Jila)mentioning

confidence: 89%

Rotating trapped Bose-Einstein condensates

2008

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“…In the more general case of two interpenetrating species, even a uniform system can have imaginary frequencies for sufficiently strong interspecies repulsion [93,94]; this dynamical instability signals the onset of phase separation.…”

Section: Bogoliubov Equations: Stability Of Small-amplitude Pertumentioning

confidence: 99%

Vortices in a trapped dilute Bose-Einstein condensate

Fetter¹,

Svidzinsky²

2001

J. Phys.: Condens. Matter

556

758

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We review the theory of vortices in trapped dilute Bose-Einstein condensates and compare theoretical predictions with existing experiments. Mean-field theory based on the time-dependent Gross-Pitaevskii equation describes the main features of the vortex states, and its predictions agree well with available experimental results. We discuss various properties of a single vortex, including its structure, energy, dynamics, normal modes and stability, as well as vortex arrays. When the nonuniform condensate contains a vortex, the excitation spectrum includes unstable ("anomalous") mode(s) with negative frequency. Trap rotation shifts the normal-mode frequencies and can stabilize the vortex. We consider the effect of thermal quasiparticles on vortex normal modes as well as possible mechanisms for vortex dissipation. Vortex states in mixtures and spinor condensates are also discussed.

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“…Phase-separation in two-component condensate mixtures is predicted by mean-field theory [15][16][17][18][19]. The mean-field interaction energy of such condensates is given by 2πh 2 /m × (n 2 a a a + n 2 b a b + 2n a n b a ab ) where m is the common atomic mass, n a and n b are the densities of each of the components, a a and a b are the same-species scattering lengths, and a ab is the scattering length for interspecies collisions.…”

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confidence: 99%

Observation of Metastable States in Spinor Bose-Einstein Condensates

et al. 1999

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Bose-Einstein condensates have been prepared in long-lived metastable excited states. Two complementary types of metastable states were observed. The first is due to the immiscibility of multiple components in the condensate, and the second to local suppression of spin-relaxation collisions. Relaxation via re-condensation of non-condensed atoms, spin relaxation, and quantum tunneling was observed. These experiments were done with F = 1 spinor Bose-Einstein condensates of sodium confined in an optical dipole trap.Metastable states of matter, excited states which relax only slowly to the ground state, are commonly encountered. This slow relaxation often arises from the presence of free-energy barriers that prevent a system from directly evolving toward its ground state; if the thermal energy to overcome this barrier is not available, the metastable state may be long-lived.Many properties of Bose-Einstein condensates in dilute atomic gases [1][2][3][4] arise from metastability; indeed, such condensates are themselves metastable, since the true equilibrium state is a solid at these low temperatures. Bose-Einstein condensates in gases with attractive interactions (scattering length a < 0) [3] are metastable against collapse due to a kinetic energy barrier [5]. The persistence of rotations in condensates with repulsive interactions (a > 0) hinges on whether vortices are metastable in singly- [6] or multiply-connected [7,8] geometries. Similarly, dark solitons in restricted geometries are predicted to be long-lived [9] akin to the recently observed metastable states in superfluid 3 He-B [10]. Finally, Pu and Bigelow discussed spatial distributions of two-species condensates which are metastable due to mean-field repulsion between the two species [11].In this Letter, we report on the observation of two complementary types of metastability in F = 1 spinor Bose-Einstein condensates of sodium. In one, a twocomponent condensate in the |F = 1, m F = 1, 0 hyperfine states was stable in spin composition, but spontaneously formed a metastable spatial arrangement of spin domains. In the other, a single component |m F = 0 condensate was metastable in spin composition with respect to the development of |m F = ±1 ground-state spin domains. In both cases, the energy barriers which caused the metastability (as low as 0.1 nK) were much smaller than the temperature of the gas (about 100 nK) which would suggest a rapid thermal relaxation. However, this thermal relaxation was slowed considerably due to the high condensate fraction and the extreme diluteness of the non-condensed cloud.Spinor Bose-Einstein condensates were created as in previous work [12]. Condensates in the |F = 1, m F = −1 state were created in a magnetic trap [13] and then transfered to an optical dipole trap formed by a single infrared laser beam [14]. The beam was weakly focused, producing cigar-shaped traps with depths of 1 -2 µK, radial trap frequencies of about 500 Hz, and aspect ratios of about 70. After transfer, Landau-Zener rf-sweeps placed the optically trappe...

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Mixtures of Bose liquids at finite temperature

Cited by 62 publications

References 5 publications

Rotating trapped Bose-Einstein condensates

Rotating trapped Bose-Einstein condensates

Vortices in a trapped dilute Bose-Einstein condensate

Observation of Metastable States in Spinor Bose-Einstein Condensates

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