Dispersive Effects in the Unitary Fermi Gas

Ancilotto, Francesco; Salasnich, Luca; Toigo, Flavio

doi:10.1007/s10909-012-0772-7

Cited by 5 publications

(14 citation statements)

References 38 publications

(77 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar coarse graining of the evolved etf was performed in [36] to compare with the shock-wave experiment [9]. The agreement there confirms this picture that the etf is suitable for modelling bulk dynamical properties.…”

Section: Nonlinear Responsesupporting

confidence: 60%

“…Despite these differences in microscopic behaviour, the etf remains a useful tool for modelling bulk dynamics. This is perhaps best demonstrated by the remarkable quantitative agreement between the etf simulations [36] and the observed shock-wave phenomena obtained experimentally by colliding two ufg clouds [9]. The quantitative agreement conclusively demonstrates that [9] is not probing dissipative effects such as viscosity which are missing in the conservative etf approach.…”

Section: Discussionmentioning

confidence: 55%

“…The etf [33,34] is essentially a bosonic theory describing dimers/Cooper-pairs in the ufg with a single collective condensate wavefunction that has been used to analyze the expansion and breathing mode frequencies of cold atomic gases in a trap [33,34], their surface oscillations [35], collisions of clouds of fermions [36], vortex generation [37], vortex pinning [32], instabilities [38], and soliton dynamics [39]. While the etf has the same symmetries, and can be tuned to have the same eos as the full theory, one expects poor behaviour when excitations approach the pair-breaking threshold set by the gap hω > 2∆ ≈ E F .…”

mentioning

confidence: 99%

See 2 more Smart Citations

Validating simple dynamical simulations of the unitary Fermi gas

Forbes

Sharma

2014

Phys. Rev. A

View full text Add to dashboard Cite

We present a comparison between simulated dynamics of the unitary fermion gas using the superfluid local density approximation (slda) and a simplified bosonic model, the extended Thomas Fermi (etf) with a unitary equation of state. Small amplitude fluctuations have similar dynamics in both theories for frequencies far below the pair breaking threshold and wave vectors much smaller than the Fermi momentum, and the low frequency linear responses match well for surprisingly large wave vectors, even up to the Fermi momentum. For non-linear dynamics such as vortex generation, the etf provides a semi-quantitative description of slda dynamics as long as the fluctuations do not have significant power near the pair breaking threshold, otherwise the dynamics of the etf cannot be trusted. Nonlinearities in the etf tends to generate high-frequency fluctuations, and with no normal component to remove this energy from the superfluid, features like vortex lattices cannot relax and crystallize as they do in the slda. We present a heuristic diagnostic for validating the reliability of etf dynamics by considering the approximate conservation of square of the gap: |∆| 2 .

show abstract

Section: Nonlinear Responsesupporting

confidence: 60%

Section: Discussionmentioning

confidence: 55%

mentioning

confidence: 99%

See 1 more Smart Citation

Validating simple dynamical simulations of the unitary Fermi gas

Forbes

Sharma

2014

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…The etf approach that has been used to analyze the expansion [28] and [28,44] breathing mode frequencies of cold atomic gases in a trap, their surface oscillations [45], collisions of clouds of fermions [46], vortex generation [47], vortex pinning [48], and soliton dynamics [49]. The etf is equivalent to the quantum hydrodynamics approach at zero temperature, which has been used extensively by many authors for modelling the unitary Fermi gas during the last decade, but etf also includes the quantum pressure term typically neglected in a hydrodynamic approach.…”

Section: Etf Modelmentioning

confidence: 99%

Quantized Superfluid Vortex Rings in the Unitary Fermi Gas

et al. 2014

View full text Add to dashboard Cite

In a recent article, Yefsah et al. [Nature (London) 499, 426 (2013)] report the observation of an unusual excitation in an elongated harmonically trapped unitary Fermi gas. After phase imprinting a domain wall, they observe oscillations almost an order of magnitude slower than predicted by any theory of domain walls which they interpret as a "heavy soliton" of inertial mass some 200 times larger than the free fermion mass or 50 times larger than expected for a domain wall. We present compelling evidence that this "soliton" is instead a quantized vortex ring, by showing that the main aspects of the experiment can be naturally explained within the framework of time-dependent superfluid density functional theories.

show abstract

“…It is noticed that the above mentioned references [24][25][26][27]31] mainly present the results of one dimensional (1D) dynamics of fermonic shock waves by integrating over the transverse coordinate. There is a lack of discussion on the transversal effect on shock wave dynamics, however, which is always present in Fermi gas experiments and of considerable practical interest.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of shock waves in a superfluid unitary Fermi gas

Wen

Shui

Shan

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

We study the formation and dynamics of shock waves initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of shock waves mediated by the quantum pressure term is purely dispersive. Our results show good agreement with the experiment of Joseph et al. [Phys. Rev. Lett. 106, 150401 (2011)]. We reveal that the boxlike-shaped density peak observed in the experiment consists of many vortex rings due to the transverse instability of the dispersive shock wave. In addition, we study the transition from a sound wave to subsonic shock waves by increasing the strength of the repulsive potential and show a strong qualitative change in the propagation speed of the wavefronts. In the relatively small strength regime, the speed decreases below the sound speed with increasing the strength as a scaling behavior, while in the large regime the speed remains almost unchanged, which is found to be the same expansion speed of the proliferation of the vortex rings.

show abstract

Dispersive Effects in the Unitary Fermi Gas

Cited by 5 publications

References 38 publications

Validating simple dynamical simulations of the unitary Fermi gas

Validating simple dynamical simulations of the unitary Fermi gas

Quantized Superfluid Vortex Rings in the Unitary Fermi Gas

Dynamics of shock waves in a superfluid unitary Fermi gas

Contact Info

Product

Resources

About