SciPost Submission Page
Mechanical stability of resonant Bose-Fermi mixtures
by Christian Gualerzi, Leonardo Pisani, Pierbiagio Pieri
Submission summary
| Authors (as registered SciPost users): | Pierbiagio Pieri · Leonardo Pisani |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2504.06681v2 (pdf) |
| Data repository: | https://zenodo.org/records/15169400 |
| Date accepted: | July 17, 2025 |
| Date submitted: | June 25, 2025, 10:26 a.m. |
| Submitted by: | Leonardo Pisani |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
We investigate the mechanical stability of Bose-Fermi mixtures at zero temperature in the presence of a tunable Feshbach resonance, which induces a competition between boson condensation and boson-fermion pairing when the boson density is smaller than the fermion density. Using a many-body diagrammatic approach validated by fixed-node Quantum Monte Carlo calculations and supported by recent experimental observations, we determine the minimal amount of boson-boson repulsion required to guarantee the stability of the mixture across the entire range of boson-fermion interactions from weak to strong coupling. Our stability phase diagrams indicate that mixtures with boson-to-fermion mass ratios near two, such as the $^{87}$Rb-$^{40}$K system, exhibit optimal stability conditions. Moreover, by applying our results to a recent experiment with a $^{23}$Na-$^{40}$K mixture, we find that the boson-boson repulsion was insufficient to ensure stability, suggesting that the experimental timescale was short enough to avoid mechanical collapse. On the other hand, we also show that even in the absence of boson-boson repulsion, Bose-Fermi mixtures become intrinsically stable beyond a certain coupling strength, preceding the quantum phase transition associated with the vanishing of the bosonic condensate. We thus propose an experimental protocol for observing this quantum phase transition in a mechanically stable configuration.
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
Author comments upon resubmission
Thank you for your Editorial Recommendation of June 17th, 2025.
As you recommended, we have considered all suggestions and requested changes by the Referees, and have implemented them in the revised version of our manuscript. Together with this resubmission, we have also sent a point-by-point response to both Referees and uploaded a list of changes.
We thank both Referees for their valuable comments and suggestions which helped us to improve our manuscript.
Yours sincerely,
Christian Gualerzi, Leonardo Pisani, Pierbiagio Pieri
List of changes
-Sec. 1, added new paragraph “In our calculations, we will focus on homogeneous mixtures…” (second to last paragraph of Sec. 1).
-Sec. 2.1, added “(see Eq. (4) below)” at the end of the second sentence of the first paragraph after Eq. (1).
-Sec. 2.2, added “and $\Theta(x)$ is the Heaviside step function of argument x .” in the first line after Eq. (5).
-Sec. 2.2, added new paragraph starting with “Equation (4) is obtained by ...” (first paragraph after Eq. (5)). This new paragraph contains two new equations (6) and (7).
-Sec. 3.1, added 4 new sentences (last four sentences of Sec. 3.1).
-Sec. 3.3, added footnote 1 at the end of Sec. 3.3.
-Bibliography, added Refs [59,61,77,78,81,85,95,97,98,101,102].
- Bibliography, eliminated former Ref. [26], which was an old preprint version of former Ref. [30], now Ref. [29].
Published as SciPost Phys. 19, 039 (2025)
Reports on this Submission
Report #2 by Anonymous (Referee 2) on 2025-7-1 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2504.06681v2, delivered 2025-07-01, doi: 10.21468/SciPost.Report.11497
Strengths
2-the paper is, in general, well organized and well written. For this reason, despite the focus on a rather specific field (the BF mixtures and their properties) and the presence of some rather technical parts, I think it should be accessible to a broad audience.
Report
Requested changes
no further changes are requested
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)
Strengths
- The presented results are original and will have an important impact on the study of Fermi-Bose ultracold mixtures
- The topic addressed is timely and relevant
Report
Requested changes
no further revisions are needed
Recommendation
Publish (easily meets expectations and criteria for this Journal; among top 50%)