Snake instability of dark solitons across the BEC-BCS crossover: An effective-field-theory perspective

Lombardi, Giovanni; Alphen, Wout Van; Klimin, S. N.; Tempere, J.

doi:10.1103/physreva.96.033609

Cited by 17 publications

(36 citation statements)

References 35 publications

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“…The soliton propagates towards the edge of the cloud and vanishes, indicating suppression of the snake instability. Phenomenon of stabilization of a dark soliton due to spin-imbalance was studied in papers [32,33] under hypothesis of system uniformity-trap effects were completely neglected and dynamics were investigated effectively in 2D. Here we confirm, that the effect survives in full 3D calculations, which is not a priori obvious, as dimensionality as well as trap effects play a very important role in the context of stability of topological defects.…”

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confidence: 65%

Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas

et al. 2018

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Cold atoms experiments offer invaluable information on superfluid dynamics, including decay cascades of topological defects. While the cascade properties are well established for Bose systems, our understanding of their behavior in Fermi counterparts is very limited, in particular in spin-imbalanced systems, where superfluid (paired) and normal (unpaired) particles naturally coexist giving rise to complex spatial structure of the atomic cloud. Here we show, based on a newly developed microscopic approach, that the decay cascades of topological defects are dramatically modified by the spin polarization. We demonstrate that decay cascades end up at different stages: "dark soliton," "vortex ring," or "vortex line," depending on the polarization. We reveal that it is caused by sucking of unpaired particles into the soliton's internal structure. As a consequence vortex reconnections are hindered and we anticipate that quantum turbulence phenomenon can be significantly affected, indicating new physics induced by polarization effects.

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confidence: 65%

Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas

et al. 2018

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“…in a 2D geometry, alias dark soliton stripes (DSS), into vortex-antivortex pairs. A significant volume of theoretical studies examined this dynamical instability [62][63][64][65][66][67][68][69][70][71][72] and the conditions under which it can be suppressed [73][74][75][76].…”

Section: Introductionmentioning

confidence: 99%

Many-body quantum dynamics in the decay of bent dark solitons of Bose–Einstein condensates

et al. 2017

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The beyond mean-field dynamics of a bent dark soliton embedded in a two-dimensional repulsively interacting Bose-Einstein condensate is explored. We examine the case of a single bent dark soliton comparing the mean-field dynamics to a correlated approach, the Multi-Configuration Time-Dependent Hartree method for Bosons. Dynamical snaking of this bent structure is observed, signaling the onset of fragmentation which becomes significant during the vortex nucleation. In contrast to the mean-field approximation "filling" of the vortex core is observed, leading in turn to the formation of filled-core vortices, instead of the mean-field vortex-antivortex pairs. The resulting smearing effect in the density is a rather generic feature, occurring when solitonic structures are exposed to quantum fluctuations. Here, we show that this filling owes its existence to the dynamical building of an antidark structure developed in the next-to-leading order orbital. We further demonstrate that the aforementioned beyond mean-field dynamics can be experimentally detected using the variance of single shot measurements. Additionally, a variety of excitations including vortices, oblique dark solitons, and open ring dark soliton-like structures building upon higher-lying orbitals is observed. We demonstrate that signatures of the higher-lying orbital excitations emerge in the total density, and can be clearly captured by inspecting the one-body coherence. In the latter context, the localization of one-body correlations exposes the existence of the multi-orbital vortex-antidark structure.

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“…The consequent limitations and validity of the EFT are discussed in section 2.2. The theory has already been successfully employed in the description of both stable dark solitons and the snake instability mechanism in different regimes of temperature and population imbalance [25][26][27]. In this work, we use the EFT equation of motion that governs the dynamics of the order parameter to numerically simulate the collision of two solitons in a 1D Fermi superfluid and study the properties of the re-emerging solitons across the BEC-BCS crossover.…”

Section: Introductionmentioning

confidence: 99%

“…The (quasi-)1D setting in which we investigate the collisions ensures that the solitons are stable with respect to the snake instability [27] and is indeed the regime of interest for most of the current theoretical and experimental studies on this subject. The 1D propagating soliton solutions which constitute the initial states for the numerical simulations are obtained from analytic expressions for the phase and amplitude profile of the order parameter, which were derived in [25,26] for the case of a dark soliton on a uniform background.…”

Section: Introductionmentioning

confidence: 99%

Dark soliton collisions in superfluid Fermi gases

et al. 2018

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In this work dark soliton collisions in a one-dimensional superfluid Fermi gas are studied across the BEC-BCS crossover by means of a recently developed finite-temperature effective field theory (2015 Eur. Phys. J. B 88 122). The evolution of two counter-propagating solitons is simulated numerically based on the theory's nonlinear equation of motion for the pair field. The resulting collisions are observed to introduce a spatial shift into the trajectories of the solitons. The magnitude of this shift is calculated and studied in different conditions of temperature and spin-imbalance. When moving away from the BEC-regime, the collisions are found to become inelastic, emitting the lost energy in the form of small-amplitude density oscillations. This inelasticity is quantified and its behavior analyzed and compared to the results of other works. The dispersion relation of the density oscillations is calculated and is demonstrated to show a good agreement with the spectrum of collective excitations of the superfluid.

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Snake instability of dark solitons across the BEC-BCS crossover: An effective-field-theory perspective

Cited by 17 publications

References 35 publications

Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas

Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas

Many-body quantum dynamics in the decay of bent dark solitons of Bose–Einstein condensates

Dark soliton collisions in superfluid Fermi gases

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