SciPost Submission Page
Quenching a Fermi superfluid across the BEC-BCS crossover
by Moritz Breyer, Daniel Eberz, Andreas Kell, Michael Köhl
Submission summary
| Authors (as registered SciPost users): | Michael Köhl |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202407_00017v1 (pdf) |
| Date submitted: | 2024-07-10 10:11 |
| Submitted by: | Köhl, Michael |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
We study the response of a Fermi superfluid to a rapid change of the interaction strength. For a broad range of quench parameters, the order parameter exhibits damped oscillations, however, we also identify quench regimes in which these oscillations are absent. By comparing our data to a numerical model we find that the damping time constants are explainable by a dephasing in a local density approximation, however, the oscillation frequencies, while being comparable to the superconducting gap parameter, display in detail significant differences to the integrable BCS model.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Strengths
1 The considered problem of the quenches in BEC-BCS crossover in itself is quite interesting
2 The experimental results on the condensate fraction are presented with a high accuracy
3 There is a comparison between experimental and theoretical results. In some cases, there is a disagreement, which opens a question for future studies
Weaknesses
1 Presentation of the data and its interpretation can be improved
Report
The Authors consider the problem of quenching the two-component fermi gas between two values of the interaction parameter in the BCS-BEC crossover. Different physical regimes are considered and the resulting phase diagram is discussed.
Although I find the obtained results interesting, and, most probably valid, I believe that the presentation should be improved before the Manuscript can be accepted for publication.
Requested changes
1 The article uses a number of concepts to quantify the properties of the quantum system, such as superconducting parameter, order parameter, and condensate fraction. It could be useful to clearly define, what exactly is meant by each quantity.
2 The title uses the term "BEC-BCS crossover ", where the term "crossover" highlights the absence of a phase transition when changing the interaction parameter. That is, nothing special happens at the point, where the chemical potential becomes equal to zero. On the other hand, in Fig 1, seems to denote a phase transition line. If this is not the case, make it dashed and provide a discussion.
3 Figures. I find it convenient to have self-sufficient explanation of the figures in the captions. The first phrase of the caption should explain what will be shown in the figure (this is done in Fig 1, but not in Fig 2 or Fig 3). Here Fig 2 and Fig 3 are grouped, so there should be a phrase before explaining panels (a),(b) and so on. Fig 1 has regions (phases?) I, II, II', III shown but not defined in the caption. Please add a description.
4 Fig 2. The font size of the axes it much smaller as compared to the size of the text. Increase the font size. Also the panels are too small. On a computer screen one can enlarge the figures, this is not possible in a printed article. I would suggest to separate one of the panels (maybe (b)) into a different figure. Also it would be good to have a legend with the quench parameters like "$0.27 \to 1.08$" together with the color code and "BEC$\to$ BEC", "BEC $\to$ BCS", etc. title.
5 Fig2b reports "signal" on the vertical axis, change it with the quantity which is measured.
6 Figure 2 is discussed twice in the text (on page 3 and page 5). Please, introduce it better the second time. Now the discussion sounds completely disconnected. It is said that "In Figure 2, we show the results of the LDA modeling in comparison with the experimental data". Well, from the legend and the caption, it is not actually clear which data is experimental and which is the prediction.
7 There is a long text description of the piecewise function which is used but its expression is not shown. It might be useful to add it explicitly.
8 I do not understand what is meant by "two" in the following sentence "We estimate the overestimation of the density to be below two ...", please rephrase.
9 expand "BCS" abbreviation in the Abstract
10 we follow [33] change to we follow Ref. ~[33]
11 "steady-states" check hyphenation, actually it might be correct
Recommendation
Ask for minor revision