Superradiance from hydrodynamic vortices: A numerical study

Federici, F.; Cherubini, Christian; Succi, Sauro; Tosi, M. P.

doi:10.1103/physreva.73.033604

Cited by 54 publications

(59 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, our system could be useful for simulating BH physics, while a similar analogy has been discussed by considering a rotating object or a vortex in superfluid systems. [34][35][36][37][38] We are grateful to S. Inouye, H. Ishihara, M. Kimura, Y. Kawaguchi, T. Kuwamoto, and T. Mizushima for useful discussions and comments on this work. This work was supported by KAKENHI from the Japan Society for the Promotion of Science (Grants No.…”

mentioning

confidence: 99%

Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?

2018

View full text Add to dashboard Cite

We revisit the fundamental problem of the splitting instability of a doubly quantized vortex in uniform singlecomponent superfluids at zero temperature. We analyze the system-size dependence of the excitation frequency of a doubly quantized vortex through large-scale simulations of the Bogoliubov-de Gennes equation, and find that the system remains dynamically unstable even in the infinite-system-size limit. Perturbation and semi-classical theories reveal that the splitting instability radiates a damped oscillatory phonon as an opposite counterpart of a quasi-normal mode.Introduction: Vortices appear in many branches of physics. In particular, the structure, stability, and dynamics of vortices in nonlinear fields share common features in many physical systems. 1) Quantized vortices are prototypes among those vortices, playing a key role in the fluid dynamics of superfluid helium and Bose-Einstein condensates (BECs). [2][3][4][5] In general, quantized vortices are characterized by the winding number of the phase of the superfluid order parameter around the vortex core. A vortex whose winding number l is more than unity is called an l-quantized or multiply quantized vortex (MQV). Since the energy of an l-quantized vortex is generally larger than the sum of energies of l singly quantized vortices (SQVs), an MQV is energetically unstable and splits into SQVs in uniform systems. 6) In fact, MQVs have never been observed in equilibrium. However, this argument does not eliminate the possibility that MQVs survive as a metastable state at very low temperatures when energy dissipation is negligible.To investigate the splitting instability precisely, we need to analyze the microscopic structure of the vortex core. It is difficult to demonstrate such an analysis in the strongly correlated superfluid 4 He. Experimentally, there is no established technique to prepare an MQV in helium superfluids as an initial state of the instability problem. The realization of MQV in the BECs of ultra-cold gases sheds light on this problem, and vortex splitting has been observed. [7][8][9] The MQV in trapped systems can be dynamically unstable, and split into vortices with smaller winding numbers according to the Bogoliubovde Gennes (BdG) analysis at zero temperature. [10][11][12][13][14][15][16][17] Dynamic instability may occur when the excitation modes have complex frequencies as a result of coupling or "mixing" between two modes with positive and negative excitation energies. The negative energy mode, called the core mode, is localized at the vortex core and decreases the angular momentum of the system by −l in the direction along the core. The positive energy mode is a collective mode of the condensate. The instability depends on the atomic interaction strength in a complicated

show abstract

mentioning

confidence: 99%

Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?

2018

View full text Add to dashboard Cite

show abstract

“…By simply shaping the amplitude profile of the coherent coupling between the internal states of the atoms, a wide variety of hydrodynamic regimes with different number and shape of the horizons can be achieved. As an example, superradiance from an analogue rotating BH [45,46] could be investigated within the spin-branch of the system without being disturbed by the microscopic structure of the vortex core. The much larger value of the spin healing length compared to the density one, ensures in fact the existence of a wide ergoregion where radiation enhancement effects can take place on top of a very flat density background far from the vortex core.…”

Section: Discussionmentioning

confidence: 99%

Black-hole lasing in coherently coupled two-component atomic condensates

2017

View full text Add to dashboard Cite

We theoretically study the black-hole lasing phenomenon in a flowing one-dimensional, coherently coupled two component atomic Bose-Einstein condensate whose constituent atoms interact via a spin-dependent s-wave contact interaction. We show by a numerical analysis the onset of the dynamical instability in the spin branch of the excitations, once a finite supersonic region is created in this branch. We study both a spatially homogeneous geometry and a harmonically trapped condensate. Experimental advantages of the two-component configuration are pointed out, with an eye towards studies of back-reaction phenomena.

show abstract

“…Assuming a homogeneous density n and a velocity profile v(r, θ) = −car + Ωa 2θ /r where c is the homogeneous speed of sound, superradiance occurs when 0 < ω s < q s Ω [130,131,132]. The increase in energy of the outgoing sound is due to an extraction of energy from the vortex and as such it is expected to lead to slowing of the vortex rotation.…”

Section: Superradiancementioning

confidence: 99%

“…For Hawking radiation it is preferable to avoid the generation of vortices [121,128], and as such will not be discussed here. However, the phenomena of superradiance in BECs, which can be considered as stimulated Hawking radiation, relies on the presence of a vortex [129,130,131,132], which is analogous to a rotating black hole.…”

Section: Analogs Of Gravitational Physics In Becsmentioning

confidence: 99%

See 1 more Smart Citation

Vortices in Bose-Einstein Condensates: Theory

Parker

Jackson

Martin

et al.

Emergent Nonlinear Phenomena in Bose-Einstein Condensates

View full text Add to dashboard Cite

Vortices are pervasive in nature, representing the breakdown of laminar fluid flow and hence playing a key role in turbulence. The fluid rotation associated with a vortex can be parameterized by the circulation $\Gamma=\oint {\rm d}{\bf r}\cdot{\bf v}({\bf r})$ about the vortex, where ${\bf v}({\bf r})$ is the fluid velocity field. While classical vortices can take any value of circulation, superfluids are irrotational, and any rotation or angular momentum is constrained to occur through vortices with quantized circulation. Quantized vortices also play a key role in the dissipation of transport in superfluids. In BECs quantized vortices have been observed in several forms, including single vortices, vortex lattices, and vortex pairs and rings. The recent observation of quantized vortices in a fermionic gas was taken as a clear signature of the underlying condensation and superfluidity of fermion pairs. In addition to BECs, quantized vortices also occur in superfluid Helium, nonlinear optics, and type-II superconductors.Comment: 17 pages, 2 figures. Book chapter to appear in "Emergent Nonlinear Phenomena in Bose-Einstein condensates: Theory and Experiment" (Springer-Verlag)

show abstract

Superradiance from hydrodynamic vortices: A numerical study

Cited by 54 publications

References 31 publications

Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?

Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?

Black-hole lasing in coherently coupled two-component atomic condensates

Vortices in Bose-Einstein Condensates: Theory

Contact Info

Product

Resources

About