Pith. sign in

REVIEW 5 minor 57 references

Native collisions plus any quadratic Zeeman shift produce scalable one-axis-twisting spin squeezing in spinor condensates.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · grok-4.5

2026-07-10 20:10 UTC pith:SREHRFML

load-bearing objection Clean theory result: spinor BECs with any quadratic Zeeman shift give universal OAT-like scalable squeezing, including a freezable stroboscopic regime.

arxiv 2607.06842 v1 pith:SREHRFML submitted 2026-07-07 quant-ph cond-mat.quant-gas

Universal spin-squeezing dynamics in spinor condensates

classification quant-ph cond-mat.quant-gas PACS 03.75.Mn42.50.Dv03.65.Ud
keywords spin squeezingspinor Bose-Einstein condensateone-axis twistingquadratic Zeeman shiftcollective spinquantum metrologyentanglement
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Spinor Bose-Einstein condensates of atoms with large internal spin already contain spin-changing collisions, but those collisions alone leave a coherent spin state unentangled. This paper shows that adding a controllable quadratic Zeeman shift is enough to drive the same ensemble into scalable spin-squeezed states. The resulting dynamics follow the universal scaling of the classic one-axis-twisting model for every strength of the Zeeman term: best squeezing improves as N to the minus two-thirds and appears after a time that grows only as N to the one-third. When the shift is weak the squeezing is continuous; when it is strong the squeezing appears only at regular stroboscopic instants. Switching the Zeeman shift off freezes the collective spin, so the prepared squeezed state can sit idle while an external field to be measured is applied. The result therefore converts an already-available experimental platform into a source of large-scale metrological entanglement without engineered multi-body interactions.

Core claim

The combination of the native spin-dependent contact interaction and an arbitrary quadratic Zeeman shift generates scalable spin squeezing of the collective spin that obeys the one-axis-twisting scalings ξ_R^{2}_min ∼ N^{-2/3} and t_min ∼ N^{1/3} for every value of the reduced Zeeman parameter q. The same dynamics can be frozen by extinguishing q, leaving the squeezed state available for arbitrary interrogation times.

What carries the argument

Two complementary effective Hamiltonians obtained by Schrieffer-Wolff (small |q|) and rotating-wave (large |q|) projections, both of which reduce to one-axis twisting plus controllable corrections; their predictions are confirmed by exact diagonalization of the full single-mode Hamiltonian up to N = 3000.

Load-bearing premise

All atoms occupy exactly the same spatial orbital, so the many-body problem collapses exactly onto a pure collective-spin Hamiltonian.

What would settle it

Measure the Wineland squeezing parameter versus atom number for a fixed small or large quadratic Zeeman shift in a spin-1 condensate; if the optimal squeezing fails to track N^{-2/3} once N exceeds a few thousand, the claim is false.

Watch this falsifier — get emailed when new claim-graph text bears on it.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

0 major / 5 minor

Summary. The manuscript shows that a spin-1 Bose-Einstein condensate in the single-mode approximation, governed by the Hamiltonian of spin-changing collisions plus a quadratic Zeeman term (Eq. 1), generates scalable collective-spin squeezing from a coherent spin state for essentially any value of the reduced quadratic shift q. For |q| ≪ 1 a Schrieffer-Wolff effective Hamiltonian reduces to one-axis twisting (Eq. 2); for |q| ≫ 1 a rotating-wave approximation yields an effective Hamiltonian (Eq. 4) that produces stroboscopic OAT-like squeezing. Exact diagonalization up to N = 3000 confirms that the optimal Wineland parameter and the optimal time obey the universal OAT scalings (ξ_R^{2})_min ∼ N^{-2/3} and t_min ∼ N^{1/3} across the explored range of q. Quenching q freezes the collective-spin observables because the residual Hamiltonian is SU(2)-invariant, allowing arbitrarily long interrogation times in a subsequent Ramsey sequence. The same framework is argued to apply to larger-spin atoms that can be prepared close to an effective S = 1 coherent state.

Significance. If correct, the result supplies a concrete, experimentally accessible route to scalable spin squeezing in spinor condensates that does not require engineered interactions or Floquet driving. The ability to freeze the squeezed state by simply turning off the quadratic Zeeman field is a practical advantage unique to this platform and directly relevant to entanglement-enhanced magnetometry. The combination of controlled effective Hamiltonians, high-N exact diagonalization, and universal scaling constitutes a solid theoretical foundation that can guide near-term experiments with ^{87}Rb, ^{23}Na and larger-spin species such as Cr, Er or Dy.

minor comments (5)
  1. End Matter, paragraph after Eq. (10): the statement that higher-order terms produce a polynomial in J_z^{2} is plausible but not demonstrated; a short remark on the radius of convergence of the Schrieffer-Wolff series would strengthen the claim that the OAT form remains dominant for all |q| ≪ 1.
  2. Fig. 2 and associated text: the exception at q = -1 is noted only in a footnote; a brief physical explanation (or a statement that the scaling is recovered for larger N) would remove any residual ambiguity about universality.
  3. Fig. 1 caption and panels (b,d): the comparison between exact dynamics and the two effective Hamiltonians is visually clear, yet the quantitative discrepancy (e.g., relative error on ξ_R^{2}) is never stated; a single sentence or inset would help the reader gauge the quality of the approximations.
  4. End Matter, preparation of S > 1 atoms: the claim of >90 % fidelity is supported by Fig. 5, but the subsequent many-body dynamics under the full spin-dependent Hamiltonian is not simulated; a short caveat that residual population in |m| > 1 may generate additional dephasing would be useful.
  5. Notation: the reduced quadratic shift q is defined with the sign of the interaction coefficient absorbed; a parenthetical reminder that experimental q_B and c_2 may have independent signs would avoid confusion when comparing with literature values.

Circularity Check

0 steps flagged

No significant circularity: scalable OAT-like squeezing is obtained from controlled effective Hamiltonians (Schrieffer-Wolff / rotating-wave) plus exact diagonalization of the microscopic single-mode Hamiltonian, with no fitted parameters or self-referential definitions entering the claimed exponents.

full rationale

The derivation chain is self-contained and non-circular. The microscopic Hamiltonian (Eq. 1) is the standard single-mode spinor-BEC model. For |q|≪1 an effective OAT Hamiltonian is obtained by a standard Schrieffer-Wolff projection onto the maximal-spin Dicke manifold (End Matter, Eqs. 5–11); the resulting α₂Jz² term is not assumed but computed order-by-order from the matrix elements of the quadratic Zeeman operator. For |q|≫1 a rotating-wave approximation in the interaction picture yields another effective Hamiltonian (Eq. 4) that again contains an explicit OAT piece. Intermediate-q regimes are treated by exact diagonalization (block-diagonal in magnetization sectors, up to N=3000) that directly measures ξ_R^{2}(t) and extracts the observed scalings (ξ_R^{2})_min∼N^{-2/3}, t_min∼N^{1/3}. Prefactors A_q, B_q are post-hoc numerical summaries of those same simulations; they are never used as inputs to “predict” the exponents. Freezing by quenching q follows immediately from residual SU(2) invariance of the interaction term. Self-citations ([45,46] for the SWT technique, [47] for a contrasting lattice case) supply standard methods or comparisons and do not underwrite the central claim. No quantity is defined in terms of the result it is said to predict, and no uniqueness theorem is imported from prior author work to force the conclusion. The single-mode premise is an explicit modeling assumption, not a circular step.

Axiom & Free-Parameter Ledger

0 free parameters · 4 axioms · 0 invented entities

The central claim rests on the standard single-mode spinor Hamiltonian plus two controlled approximations (degenerate perturbation theory and rotating-wave). No free parameters are fitted to produce the claimed exponents; q and N are scanned. No new physical entities are postulated.

axioms (4)
  • domain assumption All atoms occupy a single spatial mode ϕ(r), so the many-body Hamiltonian reduces exactly to the collective-spin form of Eq. (1).
    Stated in Model Hamiltonian section; required for every subsequent mapping and for the ED Hilbert space of size O(N).
  • standard math Schrieffer-Wolff transformation to second order yields an effective OAT Hamiltonian inside the maximal-J Dicke manifold when |q|≪1.
    End Matter; higher-order terms ~J_z^{2n} appear but do not alter the leading OAT scaling.
  • standard math Rotating-wave approximation is valid for |q|≫1, discarding terms oscillating at 2|q|.
    Used to obtain H_eff^{q>} (Eq. 4); justified by timescale separation and verified against full ED.
  • domain assumption Unitary evolution from a pure coherent spin state; no decoherence, particle loss or multimode dynamics.
    Implicit throughout; required for the claimed freezability and for the long-time metrological utility.

pith-pipeline@v1.1.0-grok45 · 18688 in / 2293 out tokens · 33097 ms · 2026-07-10T20:10:52.431489+00:00 · methodology

0 comments
read the original abstract

The production of large-scale entangled states is one of the main goals of next-generation quantum technologies, with an immediate potential for applications in the context of entanglement-assisted quantum sensing. A very promising platform to achieve this goal is offered by ultracold spinor gases, made of atoms with a large internal spin sensitive to magnetic fields. Here we show that the native spin-changing collisions in a spinor Bose-Einstein condensate, combined with an arbitrary quadratic Zeeman shift, can generate scalable spin squeezing in the collective spin of the ensemble, following the universal paradigm of the celebrated one-axis-twisting model. Squeezing dynamics is driven by the quadratic Zeeman shift when this shift is small; and by the spin-changing collisions for large shifts, in the form of stroboscopic squeezing. Turning off the Zeeman shift freezes out the collective-spin dynamics, so that the ensuing collective spin dynamics can be uniquely governed by an external field to be sensed. Our theoretical results pave the way for the use of spinor Bose gases with a large spin in fundamental studies of entanglement, as well as in advanced metrological applications.

Figures

Figures reproduced from arXiv: 2607.06842 by Emilia Witkowska, Fabio Mezzacapo, Navid Kazemiseresht, Nikolaos Giovanoudis, Tommaso Roscilde.

Figure 1
Figure 1. Figure 1: (b) shows that the effective Hamiltonian H (eff) q< of Eq. (2) captures very accurately the full dynamics for |q| ≪ 1, clearly exhibiting scalable squeezing. In the opposite limit |q| ≫ 1, scalability is preserved, modulo a fast modulation of the squeezing parameter at the frequency of 2q – namely, scalable squeezing is real￾ized stroboscopically. This modulation corresponds to an oscillation of the contra… view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5 [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4 [PITH_FULL_IMAGE:figures/full_fig_p008_4.png] view at source ↗

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

57 extracted references · 57 canonical work pages · 3 internal anchors

  1. [1]

    Gilder,The Age of Entanglement: When Quantum Physics Was Reborn(Knopf Doubleday, 2009)

    L. Gilder,The Age of Entanglement: When Quantum Physics Was Reborn(Knopf Doubleday, 2009)

  2. [2]

    M. A. Nielsen and I. L. Chuang,Quantum Computation and Quantum Information(Cambridge University Press, 2010)

  3. [3]

    I. M. Georgescu, S. Ashhab, and F. Nori, Rev. Mod. Phys.86, 153 (2014), URLhttps://link.aps.org/doi/ 10.1103/RevModPhys.86.153

  4. [4]

    Pezz` e, A

    L. Pezz` e, A. Smerzi, M. K. Oberthaler, R. Schmied, and P. Treutlein, Rev. Mod. Phys.90, 035005 (2018), URL https://link.aps.org/doi/10.1103/RevModPhys.90. 035005

  5. [5]

    Simon, Ady Stern, Michael Freedman, and Sankar Das Sarma

    R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, Rev. Mod. Phys.81, 865 (2009), URLhttp://link.aps.org/doi/10.1103/RevModPhys. 81.865

  6. [6]

    Fr´ erot, M

    I. Fr´ erot, M. Fadel, and M. Lewenstein, Reports on Progress in Physics86, 114001 (2023), URLhttps: //doi.org/10.1088/1361-6633/acf8d7

  7. [7]

    C. Song, K. Xu, H. Li, Y.-R. Zhang, X. Zhang, W. Liu, Q. Guo, Z. Wang, W. Ren, J. Hao, et al., Science365, 574 (2019), URLhttps://doi.org/10.1126/science. aay0600

  8. [8]

    Javadi-Abhari, S

    A. Javadi-Abhari, S. Martiel, A. Seif, M. Takita, and K. X. Wei,Big cats: entanglement in 120 qubits and be- yond(2025), 2510.09520, URLhttps://arxiv.org/abs/ 2510.09520

  9. [9]

    T. Monz, P. Schindler, J. T. Barreiro, M. Chwalla, D. Nigg, W. A. Coish, M. Harlander, W. H¨ ansel, M. Hennrich, and R. Blatt, Phys. Rev. Lett.106, 130506 (2011), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.106.130506

  10. [10]

    Franke, S

    J. Franke, S. R. Muleady, R. Kaubruegger, F. Kranzl, R. Blatt, A. M. Rey, M. K. Joshi, and C. F. Roos, Nature 621, 740 (2023), ISSN 1476-4687, URLhttps://doi. org/10.1038/s41586-023-06472-z

  11. [11]

    Est` eve, C

    J. Est` eve, C. Gross, A. Weller, S. Giovanazzi, and M. K. Oberthaler, Nature455, 1216 (2008), URLhttps:// doi.org/10.1038/nature07332

  12. [12]

    M. F. Riedel, P. B¨ ohi, Y. Li, T. W. H¨ ansch, A. Sinatra, and P. Treutlein, Nature464, 1170 (2010), URLhttps: //doi.org/10.1038/nature08988

  13. [13]

    L¨ ucke, M

    B. L¨ ucke, M. Scherer, J. Kruse, L. Pezz´ e, F. Deuret- zbacher, P. Hyllus, O. Topic, J. Peise, W. Ert- mer, J. Arlt, et al., Science334, 773 (2011), https://www.science.org/doi/pdf/10.1126/science.1208798, URLhttps://www.science.org/doi/abs/10.1126/ science.1208798

  14. [14]

    Gross, Journal of Physics B: Atomic, Molecular and Optical Physics45, 103001 (2012), URLhttps://dx

    C. Gross, Journal of Physics B: Atomic, Molecular and Optical Physics45, 103001 (2012), URLhttps://dx. doi.org/10.1088/0953-4075/45/10/103001. 6

  15. [15]

    L¨ ucke, J

    B. L¨ ucke, J. Peise, G. Vitagliano, J. Arlt, L. San- tos, G. T´ oth, and C. Klempt, Phys. Rev. Lett.112, 155304 (2014), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.112.155304

  16. [16]

    Luo, Y.-Q

    X.-Y. Luo, Y.-Q. Zou, L.-N. Wu, Q. Liu, M.-F. Han, M. K. Tey, and L. You, Science355, 620 (2017), https://www.science.org/doi/pdf/10.1126/science.aag1106, URLhttps://www.science.org/doi/abs/10.1126/ science.aag1106

  17. [17]

    Zou, L.-N

    Y.-Q. Zou, L.-N. Wu, Q. Liu, X.-Y. Luo, S.-F. Guo, J.-H. Cao, M. K. Tey, and L. You, Proceedings of the National Academy of Sciences115, 6381 (2018), https://www.pnas.org/doi/pdf/10.1073/pnas.1715105115, URLhttps://www.pnas.org/doi/abs/10.1073/pnas. 1715105115

  18. [18]

    Braverman, A

    B. Braverman, A. Kawasaki, E. Pedrozo-Pe˜ nafiel, S. Colombo, C. Shu, Z. Li, E. Mendez, M. Yamoah, L. Salvi, D. Akamatsu, et al., Phys. Rev. Lett.122, 223203 (2019), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.122.223203

  19. [19]

    Bornet, G

    G. Bornet, G. Emperauger, C. Chen, B. Ye, M. Block, M. Bintz, J. A. Boyd, D. Barredo, T. Comparin, F. Mez- zacapo, et al.,Scalable spin squeezing in a dipolar rydberg atom array(2023), URLhttps://arxiv.org/abs/2303. 08053

  20. [20]

    Finkelstein, R

    R. Finkelstein, R. B.-S. Tsai, X. Sun, P. Scholl, S. Di- rekci, T. Gefen, J. Choi, A. L. Shaw, and M. Endres, Nature634, 321 (2024), ISSN 1476-4687, URLhttps: //doi.org/10.1038/s41586-024-08005-8

  21. [21]

    A. Cao, W. J. Eckner, T. Lukin Yelin, A. W. Young, S. Jandura, L. Yan, K. Kim, G. Pupillo, J. Ye, N. Darkwah Oppong, et al., Nature634, 315 (2024), ISSN 1476-4687, URLhttps://doi.org/10. 1038/s41586-024-07913-z

  22. [22]

    J. Ma, X. Wang, C. Sun, and F. Nori, Physics Reports509, 89 (2011), ISSN 0370-1573, URL https://www.sciencedirect.com/science/article/ pii/S0370157311002201

  23. [23]

    Muessel, H

    W. Muessel, H. Strobel, D. Linnemann, D. B. Hume, and M. K. Oberthaler, Phys. Rev. Lett.113, 103004 (2014), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.113.103004

  24. [24]

    Pedrozo-Pe˜ nafiel, S

    E. Pedrozo-Pe˜ nafiel, S. Colombo, C. Shu, A. F. Adiy- atullin, Z. Li, E. Mendez, B. Braverman, A. Kawasaki, D. Akamatsu, Y. Xiao, et al., Nature588, 414 (2020), ISSN 1476-4687, URLhttps://doi.org/10. 1038/s41586-020-3006-1

  25. [25]

    Schulte, C

    M. Schulte, C. Lisdat, P. O. Schmidt, U. Sterr, and K. Hammerer, Nature Communications11, 5955 (2020), ISSN 2041-1723, URLhttps://doi.org/10. 1038/s41467-020-19403-7

  26. [26]

    G. P. Greve, C. Luo, B. Wu, and J. K. Thompson, Nature 610, 472 (2022), ISSN 1476-4687, URLhttps://doi. org/10.1038/s41586-022-05197-9

  27. [27]

    W. J. Eckner, N. Darkwah Oppong, A. Cao, A. W. Young, W. R. Milner, J. M. Robinson, J. Ye, and A. M. Kaufman, Nature621, 734 (2023), ISSN 1476-4687, URL https://doi.org/10.1038/s41586-023-06360-6

  28. [28]

    Moreno-Pineda, C

    E. Moreno-Pineda, C. Godfrin, F. Balestro, W. Werns- dorfer, and M. Ruben, Chem. Soc. Rev.47, 501 (2018), URLhttp://dx.doi.org/10.1039/C5CS00933B

  29. [29]

    Erhard, M

    M. Erhard, M. Krenn, and A. Zeilinger, Nature Reviews Physics2, 365 (2020), ISSN 2522-5820, URLhttps:// doi.org/10.1038/s42254-020-0193-5

  30. [30]

    M. S. Blok, V. V. Ramasesh, T. Schuster, K. O’Brien, J. M. Kreikebaum, D. Dahlen, A. Morvan, B. Yoshida, N. Y. Yao, and I. Siddiqi, Phys. Rev. X11, 021010 (2021), URLhttps://link.aps.org/doi/10. 1103/PhysRevX.11.021010

  31. [31]

    M. Qiao, G. Emperauger, C. Chen, L. Home- ier, S. Hollerith, G. Bornet, R. Martin, B. G´ ely, L. Klein, D. Barredo, et al., Nature644, 889 (2025), ISSN 1476-4687, URLhttps://doi.org/10. 1038/s41586-025-09377-1

  32. [32]

    D. M. Stamper-Kurn and M. Ueda, Rev. Mod. Phys. 85, 1191 (2013), URLhttps://link.aps.org/doi/10. 1103/RevModPhys.85.1191

  33. [34]

    Chomaz, I

    L. Chomaz, I. Ferrier-Barbut, F. Ferlaino, B. Laburthe- Tolra, B. L. Lev, and T. Pfau, Reports on Progress in Physics86, 026401 (2022), URLhttps://dx.doi.org/ 10.1088/1361-6633/aca814

  34. [35]

    C. D. Hamley, C. S. Gerving, T. M. Hoang, E. M. Bookjans, and M. S. Chapman, Nature Physics8, 305 (2012), ISSN 1745-2481, URLhttps://doi.org/10. 1038/nphys2245

  35. [36]

    T.-W. Mao, Q. Liu, X.-W. Li, J.-H. Cao, F. Chen, W.- X. Xu, M. K. Tey, Y.-X. Huang, and L. You, Nature Physics19, 1585 (2023), ISSN 1745-2481, URLhttps: //doi.org/10.1038/s41567-023-02168-3

  36. [37]

    Kitagawa and M

    M. Kitagawa and M. Ueda, Phys. Rev. A47, 5138 (1993), URLhttps://link.aps.org/doi/10. 1103/PhysRevA.47.5138

  37. [38]

    Lepoutre, K

    S. Lepoutre, K. Kechadi, B. Naylor, B. Zhu, L. Gabar- dos, L. Isaev, P. Pedri, A. M. Rey, L. Vernac, and B. Laburthe-Tolra, Phys. Rev. A97, 023610 (2018), URLhttps://link.aps.org/doi/10.1103/PhysRevA. 97.023610

  38. [39]

    C. K. Law, H. Pu, and N. P. Bigelow, Phys. Rev. Lett. 81, 5257 (1998), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.81.5257

  39. [40]

    J. Jie, Q. Guan, S. Zhong, A. Schwettmann, and D. Blume, Phys. Rev. A102, 023324 (2020), URLhttps: //link.aps.org/doi/10.1103/PhysRevA.102.023324

  40. [41]

    Kawaguchi and M

    Y. Kawaguchi and M. Ueda, Physics Reports520, 253 (2012), ISSN 0370-1573, spinor Bose–Einstein conden- sates, URLhttps://www.sciencedirect.com/science/ article/pii/S0370157312002098

  41. [42]

    Chalopin, C

    T. Chalopin, C. Bouazza, A. Evrard, V. Makhalov, D. Dreon, J. Dalibard, L. A. Sidorenkov, and S. Nascimbene, Nature Communications9, 4955 (2018), ISSN 2041-1723, URLhttps://doi.org/10. 1038/s41467-018-07433-1

  42. [43]

    Evrard, V

    A. Evrard, V. Makhalov, T. Chalopin, L. A. Sidorenkov, J. Dalibard, R. Lopes, and S. Nascimbene, Phys. Rev. Lett.122, 173601 (2019), URLhttps://link.aps.org/ doi/10.1103/PhysRevLett.122.173601

  43. [44]

    Niezgoda, D

    A. Niezgoda, D. Kajtoch, J. Dzieka´ nska, and E. Witkowska, New Journal of Physics21, 093037 (2019), URLhttps://dx.doi.org/10.1088/1367-2630/ ab4099

  44. [45]

    T. H. Yanes, M. P lodzie´ n, M. M. Sinkeviˇ cien˙ e, G.ˇZlabys, G. Juzeli¯ unas, and E. Witkowska, Physical Review Letters129(2022), URLhttps://doi.org/10.1103% 2Fphysrevlett.129.090403. 7

  45. [46]

    Hern´ andez Yanes, A

    T. Hern´ andez Yanes, A. Niezgoda, and E. Witkowska, Phys. Rev. B109, 214310 (2024), URLhttps://link. aps.org/doi/10.1103/PhysRevB.109.214310

  46. [47]

    Trifa and T

    Y. Trifa and T. Roscilde, Phys. Rev. Lett.133, 083601 (2024), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.133.083601

  47. [48]

    At the exception of the caseq=−1, for which we could not directly observe OAT scaling for the system sizes we had access to

  48. [49]

    M. A. Perlin, C. Qu, and A. M. Rey, Phys. Rev. Lett. 125, 223401 (2020), URLhttps://link.aps.org/doi/ 10.1103/PhysRevLett.125.223401

  49. [50]

    Roscilde, F

    T. Roscilde, F. Mezzacapo, and T. Comparin, Phys. Rev. A104, L040601 (2021), URLhttps://link.aps.org/ doi/10.1103/PhysRevA.104.L040601

  50. [51]

    Comparin, F

    T. Comparin, F. Mezzacapo, M. Robert-de Saint- Vincent, and T. Roscilde, Phys. Rev. Lett.129, 113201 (2022), URLhttps://link.aps.org/doi/10. 1103/PhysRevLett.129.113201

  51. [52]

    Scalable Spin Squeezing from Finite Temperature Easy-plane Magnetism

    M. Block, B. Ye, B. Roberts, S. Chern, W. Wu, Z. Wang, L. Pollet, E. J. Davis, B. I. Halperin, and N. Y. Yao,A universal theory of spin squeezing(2023), URLhttps: //arxiv.org/abs/2301.09636

  52. [53]

    Exponential onset of scalable entanglement via twist-and-turn dynamics in XY models

    T. Roscilde, M. Kumari, A. Cooper, and F. Mezzacapo, Exponential onset of scalable entanglement via twist-and- turn dynamics in xy models(2025), 2507.08206, URL https://arxiv.org/abs/2507.08206

  53. [54]

    Geier, N

    S. Geier, N. Thaicharoen, C. Hainaut, T. Franz, A. Salzinger, A. Tebben, D. Grimshandl, G. Z¨ urn, and M. Weidem¨ uller, Science374, 1149 (2021), https://www.science.org/doi/pdf/10.1126/science.abd9547, URLhttps://www.science.org/doi/abs/10.1126/ science.abd9547

  54. [55]

    Lepoutre, J

    S. Lepoutre, J. Schachenmayer, L. Gabardos, B. Zhu, B. Naylor, E. Mar´ echal, O. Gorceix, A. M. Rey, L. Vernac, and B. Laburthe-Tolra, Nature Communi- cations10, 1714 (2019), ISSN 2041-1723, URLhttps: //doi.org/10.1038/s41467-019-09699-5

  55. [56]

    Aikawa, A

    K. Aikawa, A. Frisch, M. Mark, S. Baier, A. Riet- zler, R. Grimm, and F. Ferlaino, Phys. Rev. Lett. 108, 210401 (2012), URLhttps://link.aps.org/doi/ 10.1103/PhysRevLett.108.210401

  56. [57]

    Claude, L

    F. Claude, L. Lafforgue, J. J. A. Houwman, M. J. Mark, and F. Ferlaino, Phys. Rev. Res.6, L042016 (2024), URLhttps://link.aps.org/doi/10.1103/ PhysRevResearch.6.L042016

  57. [58]

    M. Lu, N. Q. Burdick, S. H. Youn, and B. L. Lev, Phys. Rev. Lett.107, 190401 (2011), URLhttps://link.aps. org/doi/10.1103/PhysRevLett.107.190401. END MATTER Effective Hamiltonian for|q| ≪1.The initial state of the evolution,|CSS x⟩, belongs to the Dicke subspace of states with maximalJ 2 =N(N+ 1); yet the quadratic Zeeman shift leads to a dynamics leaking...