Excited spin states and phase separation in spinor Bose-Einstein condensates

Matuszewski, Michał; Alexander, Tristram J.; Kivshar, Yuri S.

doi:10.1103/physreva.80.023602

Cited by 41 publications

(94 citation statements)

References 49 publications

(112 reference statements)

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“…Since the Hamiltonian is invariant with respect to such spin rotations, we consider only the effects of the quadratic Zeeman shift [17,18]. For sufficiently weak magnetic field we can approximate it by a positive energy shift of the m f = ±1 sublevels…”

Section: The Model and Its Phase Diagrammentioning

confidence: 99%

Dynamics of the modified Kibble-Żurek mechanism in antiferromagnetic spin-1 condensates

et al. 2013

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We investigate the dynamics and outcome of a quantum phase transition from an antiferromagnetic to phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We explicitly demonstrate double universality in dynamics within experiments with various quench time. Furthermore, we show that spin domains created in the nonequilibrium transition constitute a set of mutually incoherent quasicondensates. The quasicondensates appear to be positioned in a semiregular fashion, which is a result of the conservation of local magnetization during the post-selection dynamics.

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Section: The Model and Its Phase Diagrammentioning

confidence: 99%

Dynamics of the modified Kibble-Żurek mechanism in antiferromagnetic spin-1 condensates

et al. 2013

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“…In the case of a homogeneous system V (x) = 0, one has to take into account the possibility of phase separation which occurs due to the relation between the self-and cross-scattering terms in the Hamiltonian, as it has been observed experimentally [23]. [22]. Moreover, the antiferromagnetic 2C state remains dynamically stable, up to a critical field b c > b 1 [12].…”

Section: Antiferromagnetic Spinor Condensates In One Dimensionmentioning

confidence: 99%

“…Since the Hamiltonian is invariant with respect to such spin rotations, we consider only the effects of the quadratic Zeeman shift [21,22]. For a sufficiently weak magnetic field we can approximate it by a positive energy shift of the m f = ±1 sublevels δ = (E + + E − − 2E 0 )/2 ≈ B 2 A, where B is the magnetic field strength and A = (g I + g J ) 2 μ 2 B /16E HFS , where g I and g J are the gyromagnetic ratios of the electron and nucleus, μ B is the Bohr magneton, and E HFS is the hyperfine energy splitting at zero magnetic field [21,22]. Finally, the spin-dependent Hamiltonian (2) becomes…”

Section: Antiferromagnetic Spinor Condensates In One Dimensionmentioning

confidence: 99%

Nonadiabatic quantum phase transition in a trapped spinor condensate

2016

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We study the effect of an external harmonic trapping potential on an outcome of the nonadiabatic quantum phase transition from an antiferromagnetic to a phase-separated state in a spin-1 atomic condensate. Previously, we demonstrated that the dynamics of an untrapped system exhibits double universality with two different scaling laws appearing due to the conservation of magnetization. We show that in the presence of a trap, double universality persists. However, the corresponding scaling exponents are strongly modified by the transfer of local magnetization across the system. The values of these exponents cannot be explained by the effect of causality alone, as in the spinless case. We derive the appropriate scaling laws based on a slow diffusive-drift relaxation process in the local density approximation.

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“…, where E HFS is the hyperfine energy splitting at zero magnetic field, α = (g I + g J )µ B B/E HFS , µ B is the Bohr magneton, g I and g J are the gyromagnetic ratios of electron and nucleus, and B is the magnetic field strength [17].…”

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confidence: 99%

“…This argument also allows to understand the absence of rotonlike instability in ferromagnetic condensates. In this case, the excited nematic and 2C states [17] are characterized by zero transverse spin, and the spin conservation does not prevent energy relaxation.…”

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Rotonlike Instability and Pattern Formation in Spinor Bose-Einstein Condensates

Matuszewski

2010

Phys. Rev. Lett.

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We show that metastable phases of an antiferromagnetic spin-1 condensate in a simple model with pure contact interactions can exhibit a rotonlike minimum in the excitation spectrum. The introduction of magnetic field gives rise to the instability of roton modes, which can lead to spontaneous emergence of regular periodic, polygonal, polyhedral or crystalline patterns, as shown in numerical simulations within the truncated Wigner approximation. An explanation of the occurrence of rotonlike instability is given based on the energy and spin conservation laws.PACS numbers: 03.75. Kk, 03.75.Mn, 67.85.De, 67.85.Fg Bose-Einstein condensates with spin degrees of freedom [1] attracted in recent years great interest due to the unique possibility of exploring fundamental concepts of quantum mechanics in a remarkably controllable and tunable environment. The ability to generate spin squeezing and entanglement [2] makes spinor Bose gases promising candidates for applications as quantum simulators [3], in quantum information [4], and for precise measurements [5]. Moreover, spinor condensates were successfully used to recreate many of the phenomena of condensed matter physics in experiments displaying an unprecedented level of control over the quantum system. In particular, spin domains [6], spin mixing [7], and spin vortices [8] were predicted and observed.The fundamental concept of a roton excitation, first introduced by Landau in the context of superfluid helium, is crucial for understanding of its physical properties [9]. It is characterized by a minimum in the spectrum of excitations occurring at a finite wavelength,. If the roton gap ∆ can be decreased by changing the system parameters, the softening of the roton mode can eventually lead to an instability. This instability scenario is encountered also in many other branches of quantum physics, including strongly correlated Fermions [10], quantum Hall systems [11], and Bose-Einstein condensates with long range interactions [12][13][14]. The roton instability is characterized by unstable modes with wavevector lengths close to the roton minimum k 0 . It was suggested that it can lead to the emergence of the peculiar supersolid state [15], and several other physical phenomena [16].Here, we show that rotonlike instability can occur in spinor Bose-Einstein condensates in a simple model with pure contact interactions. It can take place in appropriately prepared metastable states of an antiferromagnetic spin-1 condensate [17] under the influence of magnetic field. Moreover, we show that, depending on the geometry and the trapping potential, it can lead to spontaneous emergence of variety of transient ordered patterns, including polygonal, polyhedral and crystalline structures. We show that these results can be verified in experiments with 23 Na condensate, which is characterized by very weak dipolar interactions [18]. We provide an explanation for the occurrence of rotonlike instability based on energy and spin conservation laws, and demonstrate how the pattern characteristic...

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Excited spin states and phase separation in spinor Bose-Einstein condensates

Cited by 41 publications

References 49 publications

Dynamics of the modified Kibble-Żurek mechanism in antiferromagnetic spin-1 condensates

Dynamics of the modified Kibble-Żurek mechanism in antiferromagnetic spin-1 condensates

Nonadiabatic quantum phase transition in a trapped spinor condensate

Rotonlike Instability and Pattern Formation in Spinor Bose-Einstein Condensates

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