Splitting Times of Doubly Quantized Vortices in Dilute Bose-Einstein Condensates

Huhtamäki, Jukka; Möttönen, Mikko; Isoshima, Tomoya; Pietilä, Ville; Virtanen, Seppo

doi:10.1103/physrevlett.97.110406

Cited by 68 publications

(80 citation statements)

References 18 publications

(30 reference statements)

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“…In their recent Letter [1], Huhtamäki et al theoretically investigated the splitting of a topologically imprinted doubly charged vortex into two singly charged vortices as occurring in a dilute atomic Bose-Einstein condensate. They compare the results of simulation with recent experiment [2] and show that the combination of gravitational sag and the time dependence of the trapping potential alone are enough to explain the observed splitting times.…”

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confidence: 99%

Splitting of doubly quantized vortices in dilute Bose-Einstein condensates

et al. 2008

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We investigate the dynamics of doubly charged vortices generated in dilute Bose-Einstein condensates by using the topological phase imprinting technique. We find splitting times of such vortices and show that thermal atoms are responsible for their decay.In their recent Letter [1], Huhtamäki et al. theoretically investigated the splitting of a topologically imprinted doubly charged vortex into two singly charged vortices as occurring in a dilute atomic Bose-Einstein condensate. They compare the results of simulation with recent experiment [2] and show that the combination of gravitational sag and the time dependence of the trapping potential alone are enough to explain the observed splitting times. Based on such an outcome the authors of Ref. [1] claim that, contrary to previous theoretical results [3], the thermal excitations are not relevant in modeling the experiment of Ref. [2]. We are going to show in this Brief Report that, indeed, the opposite is true. In fact, a number of thermal (uncondensed) atoms appears in the system while disturbing the gas. They continue to appear after the perturbation is over and until the doubly quantized vortex breaks into two singly quantized vortices. The overall number of uncondensed atoms remains approximately on the level of 20%, which is already at the edge of experimental detection capabilities. However, the uncondensed atoms do not form the broad cloud allowing the identification by fitting to a bimodal distribution -they are rather located in the core of the vortex and therefore are harder to detect. Perhaps, the signatures of the presence of thermal atoms in vortices cores are already visible in experiment in a way that after splitting the cores of two singly charged vortices get darker in comparison with the core of initially imprinted doubly quantized vortex (see Fig. 2 in Ref. [2]).To investigate the thermal excitations in a Bose gas we use the classical fields approximation [4] -an approach that treats both condensed and thermal atoms at the same footing until the detection time when the splitting into the condensate and the thermal cloud occurs. Technically, such a decomposition requires calculation of time and space average of a one-particle density matrix built of the classical field evolving according to the GrossPitaevskii equation [4].Therefore, we have repeated the calculations of Ref. Fig. 1 clearly shows that the uncondensed atoms appear in the system during the evolution. Although initially all atoms are in the condensate (i.e., the condensate fraction equals 1 as in Fig. 1(e)), already after 6 ms distinguishable fraction of uncondensed atoms is produced. This is not surprising since the process of imprinting the vortex is accompanied by a sudden squeeze of the condensate in the radial direction and a kick of it in the vertical direction [2]. The thermal atoms continue to appear after the imprinting is over and until the doubly quantized vortex splits into two singly charged vortices (production of thermal atoms while the system was initially at zero ...

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Splitting of doubly quantized vortices in dilute Bose-Einstein condensates

et al. 2008

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“…This instability is observed experimentally in various situations whose typical examples include the splitting of a multiply quantized vortex [1] and the decaying of a condensate flowing in an optical lattice [2]. Theoretically, the dynamics of condensates are well described by the time-dependent Gross-Pitaevskii (TDGP) equation [3], and theoretical studies solving the TDGP equation successfully explained the experiment of vortex splitting [4,5]. When judging whether the condensate is dynamically unstable, we may employ the Bogoliubov-de Gennes (BdG) equation [6][7][8], which is obtained by linearizing the TDGP equation.…”

Section: Introductionmentioning

confidence: 95%

Analytical study of parameter regions of dynamical instability for two-component Bose-Einstein condensates with coaxial quantized vortices

Hoashi

Nakamura²,

Yamanaka³

2016

Phys. Rev. A

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The dynamical instability of weakly interacting two-component Bose-Einstein condensates with coaxial quantized vortices is analytically investigated in a two-dimensional isotopic harmonic potential. We examine whether complex eigenvalues appear on the Bogoliubov-de Gennes equation, implying dynamical instability. Rather than solving the Bogoliubov-de Gennes equation numerically, we rely on a perturbative expansion with respect to the coupling constant which enables a simple, analytic approach. For each pair of winding numbers and for each magnetic quantum number, the ranges of inter-component coupling constant where the system is dynamically unstable are exhaustively obtained. Co-rotating and counter-rotating systems show distinctive behaviors. The latter is much more complicated than the former with respect to dynamical instability, particularly because radial excitations contribute to complex eigenvalues in counter-rotating systems.

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“…(5)]. In the case of a multiquantum vortex, dynamical instability typically signifies that the vortex is unstable against splitting into singly quantized vortices [24][25][26][27][28][29][30][31].…”

Section: Theoretical and Numerical Methodsmentioning

confidence: 99%

“…However, a serious challenge is posed by the dynamical instability of the giant vortices that becomes more pronounced as the vorticity increases [20,23]. Dynamical instabilities can lead to dissociation of the vortex even in the absence of dissipation [24][25][26][27][28][29][30][31], and therefore their effect cannot be disposed of by reducing temperature.…”

Section: Introductionmentioning

confidence: 99%

Stabilization and Pumping of Giant Vortices in Dilute Bose–Einstein Condensates

Kuopanportti

Möttönen

2010

J Low Temp Phys

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Recently, it was shown that giant vortices with arbitrarily large quantum numbers can possibly be created in dilute Bose-Einstein condensates by cyclically pumping vorticity into the condensate. However, multiply quantized vortices are typically dynamically unstable in harmonically trapped nonrotated condensates, which poses a serious challenge to the vortex pump procedure. In this theoretical study, we investigate how the giant vortices can be stabilized by the application of a Gaussian potential peak along the vortex core. We find that achieving dynamical stability is feasible up to high quantum numbers. To demonstrate the efficiency of the stabilization method, we simulate the adiabatic creation of an unsplit 20-quantum vortex with the vortex pump.

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Splitting Times of Doubly Quantized Vortices in Dilute Bose-Einstein Condensates

Cited by 68 publications

References 18 publications

Splitting of doubly quantized vortices in dilute Bose-Einstein condensates

Splitting of doubly quantized vortices in dilute Bose-Einstein condensates

Analytical study of parameter regions of dynamical instability for two-component Bose-Einstein condensates with coaxial quantized vortices

Stabilization and Pumping of Giant Vortices in Dilute Bose–Einstein Condensates

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