Anisotropic instabilities in trapped spinor Bose-Einstein condensates

Baraban, M.; Song, Hongwen; Girvin, S. M.; Glazman, L. I.

doi:10.1103/physreva.78.033609

Cited by 6 publications

(9 citation statements)

References 15 publications

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“…Initially, we take q = q i to be the largest energy parameter in the Hamiltonian and quench to a final state q = q f where 0 ≤ q f < q 0 . For short times, the dynamics is expected to be well-described by expanding the Hamiltonian to quadratic order around the initial polar state [3][4][5][6][7][8][9], Ψ = √ n 0 (0, 1, 0) T . Under this expansion the Hamiltonian becomes…”

Section: Short-time Theorymentioning

confidence: 99%

“…Motivated by this experiment, here we consider the evolution of spin textures following a quench from the polar phase to the ferromagnetic phase. While the short-time growth of magnetization during such a quench has been analyzed [3][4][5][6][7][8][9][10][11], here we consider the evolution over much longer periods and study the manner in which the spin degrees of freedom thermalize following the quench. Applying the truncated Wigner approximation (TWA) to this problem (for an overview of the TWA method and its applications, see Refs.…”

Section: Introductionmentioning

confidence: 99%

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Prethermalization in quenched spinor condensates

2011

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Motivated by recent experiments, we consider the dynamics of spin-one spinor condensates after a quantum quench from the polar to ferromagnetic state from varying the quadratic Zeeman field q. We apply the Truncated Wigner Approximation (TWA) to the spinor system, including all spatial and spin degrees of freedom. For short times, we find full agreement with the linearized Bogoliubov analysis. For longer times, where the Bogoliubov theory fails, we find that the system reaches a quasi-steady prethermalized state. We compute the Bogoliubov spectrum about the ferromagnetic state with general q and show that the resulting finite temperature correlation functions grossly disagree with the full TWA results, thus indicating that the system does not thermalize even over very long time scales. Finally we show that the absence of thermalization over realistic time scales is consistent with calculations of Landau damping rates of excitations in the finite-temperature condensate.Comment: 7 page

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Section: Short-time Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prethermalization in quenched spinor condensates

2011

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“…An analysis based on spin excitation modes allows for a good understanding of recent experiments in F = 1 87 Rb condensates, including spin-texture formation after a quench [20,23], and -in combination with dipolar interaction -the instability of externally induced helices [24,25,26]. The initial state may be represented by a spinor wave function Ψ 0 ( r) = (ψ −2 , ψ −1 , ψ 0 , ψ 1 , ψ 2 ) T = (0, 0, n 0 ( r) 1/2 , 0, 0) T .…”

Section: Figmentioning

confidence: 99%

“…This instability rate presents pronounced maxima and minima as a function of the applied field, which result in the striking multi-resonant magnetic field dependence of the pair creation efficiency (from m F = 0 to m F = ±1) observed in our experiments. Along with these resonances we observe characteristic magnetization patterns which depend on both the magnetic field [9,18,19] and the external confinement [19,20]. To investigate this magnetic field dependence experimentally, we initially prepare a sample of 10 6 87 Rb-atoms in the F = 2, m F = 2 state in a crossed beam optical dipole trap at a wavelength of 1064 nm (see Refs.…”

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Multiresonant Spinor Dynamics in a Bose-Einstein Condensate

et al. 2009

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We analyze the spinor dynamics of a 87 Rb F = 2 condensate initially prepared in the mF = 0 Zeeman sublevel. We show that this dynamics, characterized by the creation of correlated atomic pairs in mF = ±1, presents an intriguing multi-resonant magnetic field dependence induced by the trap inhomogeneity. This dependence is directly linked to the most unstable Bogoliubov spin excitations of the initial mF = 0 condensate, showing that, in general, even a qualitative understanding of the pair creation efficiency in a spinor condensate requires a careful consideration of the confinement.Spinor Bose-Einstein condensates (BECs), consisting of atoms with non-zero spin, constitute an ideal scenario to investigate the interplay between internal and external degrees of freedom in a multi-component superfluid. The competition between spin-dependent collisional interactions, Zeeman effect, and inhomogeneous trapping results in an exciting range of fundamental phenomena. As a result, spinor BECs have attracted large attention since the pioneering experiments in optical traps [1] concerning their ground state properties [2,3,4,5] and the spinor dynamics induced by the spin-changing collisions, which allow for a coherent transfer between different spin components [6,7].Spinor BECs also provide exciting perspectives as novel sources of non-classical states of matter. In this sense, condensates initially prepared in the m F = 0 Zeeman sublevel are especially fascinating [6,7,8,9]. In that case, the creation of correlated pairs results in the growth of macroscopic populations in m F = ±1. This amplification process is ideally triggered by quantum spin fluctuations [10]. Interestingly, it closely resembles parametric amplification in optical parametric down conversion [11], opening exciting new routes for matter-wave squeezing and atomic Einstein-Podolsky-Rosen entanglement experiments [12,13].Correlated pair creation, and in general any spinor dynamics, demands a significant rate of spin-changing collisions. In typical experiments these collisions are suppressed by the quadratic Zeeman effect (QZE) already in the presence of moderate magnetic fields [6]. However, the influence of the QZE at low fields is far from trivial [8,14,15,16,17]. In particular, spin-mixing can reach a pronounced maximum for low but finite fields. This resonance, contrary to those discussed below, has a non-linear character and has been explained in terms of phase matching [16].The understanding of the magnetic-field dependence of the pair creation efficiency is hence crucial for the characterization of novel spinor-based sources of non-classical matter waves. In this Letter we show that this dependence generally presents an intriguing non-monotonous character which is crucially determined by the trap inhomogeneity and cannot be explained from the physics of homogeneous BECs [18]. The pair creation efficiency is directly linked to the instability rate, which characterizes the exponential growth of the most unstable spin excitations of the initial BEC in m F...

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Dipolar and spinor bosonic systems

Yukalov

2018

Laser Phys.

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The main properties and methods of describing dipolar and spinor atomic systems, composed of bosonic atoms or molecules, are reviewed. The general approach for the correct treatment of Bose-condensed atomic systems with nonlocal interaction potentials is explained. The approach is applied to Bose-condensed systems with dipolar interaction potentials. The properties of systems with spinor interaction potentials are described. Trapped atoms and atoms in optical lattices are considered. Effective spin Hamiltonians for atoms in optical lattices are derived. The possibility of spintronics with cold atom is emphasized. The present review differs from the previous review articles by concentrating on a thorough presentation of basic theoretical points, helping the reader to better follow mathematical details and to make clearer physical conclusions.Cold atomic and molecular bosonic systems have recently been the objects of intensive research, both experimental and theoretical. First, the attention has been concentrated on dilute systems, composed of particles characterized by local interaction potentials, independent of spins, whose properties are well described by the s-wave scattering length. There are several books [1-4] and review articles [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] covering different aspects of such bosonic systems with spin-independent local interaction potentials.In the present review, bosonic atoms or molecules are treated interacting through nonlocal interaction potentials, such as dipolar potential, and interacting through spinor forces that are local but depending on the effective spins related to hyperfine states. Although there exist reviews devoted to dipolar [20][21][22][23][24][25] and spinor [26,27] systems (see also [3,28]) the present paper differs from them in the following aspects. First, our aim here is not a brief enumeration of particular cases, numerical calculations, and different experiments, but the attention here is concentrated on the principal theoretical points allowing for the correct treatment of dipolar and spinor systems. Second, more attention is payed to the derivation of effective spin Hamiltonians for atoms and molecules in optical lattices. Third, the possibility of spintronics with cold atoms and molecules, interacting through dipolar and spinor forces, is discussed.The exposition of the material is organized so that the main mathematical points be clear to the reader. More technical details can be found in the tutorials [29,30]. Throughout the paper, the system of units is employed where the Boltzmann and Planck constants are set to one, k B = 1 and = 1.As is evident, the equation for the vacuum coherent field (2.40) differs form the equation (2.34) for the condensate function that is a coherent field, but, generally, not the vacuum coherent field. Equation (2.40) is a particular case of (2.34), where there are no uncondensed particles, so that ρ 1 , σ 1 , as well as ξ, are zero.One often confuses equation (2.40) for the vacuum coherent field with me...

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Anisotropic instabilities in trapped spinor Bose-Einstein condensates

Cited by 6 publications

References 15 publications

Prethermalization in quenched spinor condensates

Prethermalization in quenched spinor condensates

Multiresonant Spinor Dynamics in a Bose-Einstein Condensate

Dipolar and spinor bosonic systems

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