Controllable nonlocal interactions between dark solitons in dipolar condensates

Bland, Thomas; Edmonds, Matthew; Proukakis, N. P.; Martin, A. M.; O’Dell, D. H. J.; Parker, N. G.

doi:10.1103/physreva.92.063601

Cited by 36 publications

(42 citation statements)

References 71 publications

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“…several individual solitons forming bound objects) and also breathers, which are single solitonic entities that can be thought of as excited states of the focussing nonlinear Schrödinger equation, which have recently been engineered experimentally with matter waves for the first time [70] using an attractive gas of 85 Rb. Soliton molecules have been studied in various guises within the context of ultracold matter, for example the realization of degeneracy with atomic species possessing significant dipole-dipole interactions has led to the prediction of novel molecular states in these systems [71][72][73]. Related to this are the realisation of 'droplets' of both dipolar matter [74][75][76] and intriguingly, also light with a non-trivial angular momentum structure [77], as well as the prediction of soliton molecules in systems with nonlocal interactions [78].…”

Section: Soliton Molecules 41 Soliton Trimersmentioning

confidence: 99%

Coherent impurity transport in an attractive binary Bose–Einstein condensate

2019

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We study the dynamics of a soliton-impurity system modeled in terms of a binary Bose-Einstein condensate. This is achieved by 'switching off' one of the two self-interaction scattering lengths, giving a two component system where the second component is trapped entirely by the presence of the first component. It is shown that this system possesses rich dynamics, including the identification of unusual 'weak' dimers that appear close to the zero inter-component scattering length. It is further found that this system supports quasi-stable trimers in regimes where the equivalent single-component gas does not, which is attributed to the presence of the impurity atoms which can dynamically tunnel between the solitons, and maintain the required phase differences that support the trimer state. that the single component focussing nonlinear Schrödinger equation can possess chaotic solutions in the presence of an axial harmonic potential [29,30], as well as the observed interaction induced frequency shift of pairs of trapped bright solitons [31] in the experiment of [13]. Complementary to this, theoretical work has focussed on solitary waves in higher spin systems, revealing the existance of integrable points in the full parameter space of the spin-1 condensate, in the form of so-called 'polar' bright solitons [32,33]. Although solitons are usually studied as the solutions to one-dimensional nonlinear models, there have also been predictions of stable two-dimensional solitary wave solutions in dipolar Bose-Einstein condensates [34,35], where the additional nonlocal nonlinearity provides the stabilizing mechanism for these solitons. Very recently the Jones-Roberts soliton was realized experimentally, a true two-dimensional solitary wave structure [36].The realization of artificial electromagnetism with cold gases, and in particular spin-orbit coupling for Bose-Einstein condensates opens a novel route towards studying nonlinear wave structures. Here, the coupling of the condensates momentum to a quasi-spin leads to stripe-like soliton phases, related to the underlying immiscible phase of these systems [37,38]. Spin-orbit coupling forms a key ingredient in simulating more exotic scenarios, such as Dirac-like equations, where confined solutions have been predicted [39] that resemble their bright soliton cousins in single component condensates.Atomic condensates benefit from being exceptionally pure systems-this in turn allows one to investigate the effects of disorder and defects with an unprecedented level of control. The presence of impurities in ensembles of ultracold matter has led to predictions of impurity-molecules and lattices at the mean-field level [40], as well as the role of many-body correlations for a single impurity out-of-equilibrium [41]. Experimental work has studied the role that spin impurities have in the strongly correlated Tonks-Girardeau limit [42] and also magnetic spin models [43], which have also been the focus of subsequent theoretical investigations [44][45][46]. Complementary to this, recent exper...

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Section: Soliton Molecules 41 Soliton Trimersmentioning

confidence: 99%

Coherent impurity transport in an attractive binary Bose–Einstein condensate

2019

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“…For purely dipolar (g = 0), oblate condensates, Wilson et al [120,122] numerically found vortex ripples for moderate trap ratios 17 γ ∼ , see figure 7 (top) [120], and established the link to roton mixing into the vortex solution, similar to the biconcave structure that they found was induced in vortex-free dipolar condensates (energetic favourability of dipoles aligning head-to-tail). Vortex ripples have since been studied in other works [123,129,134], and similar ripples arise in the presence of other localized density depletions, such as due to localized repulsive potentials [122,130] and dark solitons [149,150]. The presence of the vortex slightly reduces the stable parameter space for the condensate relative to the vortex-free condensate [120,144].…”

Section: General Features Of a Vortex In A Quantum Ferrofluidmentioning

confidence: 99%

Vortices and vortex lattices in quantum ferrofluids

Martin

Marchant

O’Dell

et al. 2017

J. Phys.: Condens. Matter

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The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose-Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross-Pitaevskii equation, ranging from analytic treatments based on the Thomas-Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii-Kosterlitz-Thouless transition.

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“…Thus, in the rapid-rotation limit, the tilt angle ϕ may be used to tune the effective strength of the DDI and in particular, when cos 2 ϕ > 1 3, the effective DDI strength becomes negative, corresponding to an unusual 'antidipolar' regime in which side-by-side alignment of the dipole moments is energetically preferred to head-to-tail alignments. Subsequent theoretical studies of dipolar BECs in this regime, which invoked the rotational tuning mechanism by setting C dd < 0, led to predictions of novel physics such as molecular bound states in dark solitons [24], multi-dimensional dark [25] and bright [26,27] solitons, stratified turbulence [28] and the roton instability of vortex lines [29]. In this direction, a recent experimental study of rotational tuning by Tang et al [30] has reported a realization of the anti-dipolar regime.…”

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confidence: 99%

Instability of Rotationally Tuned Dipolar Bose-Einstein Condensates

et al. 2019

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The possibility of effectively inverting the sign of the dipole-dipole interaction, by fast rotation of the dipole polarization, is examined within a harmonically trapped dipolar Bose-Einstein condensate. Our analysis is based on the stationary states in the Thomas-Fermi limit, in the corotating frame, as well as direct numerical simulations in the Thomas-Fermi regime, explicitly accounting for the rotating polarization. The condensate is found to be inherently unstable due to the dynamical instability of collective modes. This ultimately prevents the realization of robust and long-lived rotationally tuned states. Our findings have major implications for experimentally accessing this regime.

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Controllable nonlocal interactions between dark solitons in dipolar condensates

Cited by 36 publications

References 71 publications

Coherent impurity transport in an attractive binary Bose–Einstein condensate

Coherent impurity transport in an attractive binary Bose–Einstein condensate

Vortices and vortex lattices in quantum ferrofluids

Instability of Rotationally Tuned Dipolar Bose-Einstein Condensates

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