{"id":"b54ecafa-6550-406e-bf57-f580796bde96","arxiv_id":"2607.24152","paper_version":1,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"low","formal_verification":"none","parameter_count":3,"one_line_summary":"Reanalysis of Widmann et al. polariton coherence data shows exponential-Gaussian decays and a normalization artifact, not KPZ universal scaling in the reported space-time windows.","lead":"A comment reanalyzes polariton-condensate coherence data from a Science paper and finds exponential-in-time and Gaussian-in-space decay, not KPZ stretched exponentials. The reported KPZ data collapse is attributed to incorrect normalization, so the original claim of 2D KPZ scaling is not supported in the windows studied.","discovery_kind":"replication","skeptic_critique":{"model":"moonshotai/kimi-k3","headline":"The pure-line-shape comparison may misrepresent KPZ at fixed nonzero separation: finite-offset KPZ is a crossover form, not necessarily a stretched exponential within the selected windows.","rationale":"The reader correctly identified the fixed-window, pure-model comparison as the weakest assumption. I think that concern is concrete enough that the present evidence should not yet receive an unconditional high-confidence ACCEPT: the temporal KPZ model appears to have been tested in an asymptotic form although the measurement cut is at nonzero spatial separation. The comment’s evidence is nevertheless substantial: it covers both lattices and multiple powers, directly reproduces the reported collapse without normalization, and gives an analytic demonstration of how a normalization offset can manufacture apparent KPZ asymptotes. Those results justify treating the original collapse as suspect. What remains unsettled is the stronger inference that KPZ dynamics is not an appropriate description anywhere within the analyzed windows. A finite-offset KPZ fit using the known scaling function, with model-selection penalties and propagated normalization uncertainty, would directly test that inference. I would therefore make acceptance conditional on that reanalysis rather than reject the comment.","tokens_in":9463,"tokens_out":6313,"duration_ms":213115,"concrete_test":"For every released temporal cut at the actual \\(r_0\\), fit \\(-2\\ln|\\kappa g^{(1)}|\\) using the tabulated 2D FRG function in the finite-offset KPZ form \\(t^{2\\beta}F(C_1r_0/t^{1/z})\\), rather than \\(At^{2\\beta}\\), and fit the same points with the exponential-Gaussian model. Use identical weights/windows, report AIC/BIC and bootstrap parameter uncertainties. If finite-offset KPZ is preferred or statistically competitive in an intermediate subwindow, the comment’s exclusion claim weakens; if exponential-Gaussian wins decisively across powers and lattices, the concern does not land.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The comment’s Table I and Sec. II compare a pure KPZ stretched exponential in time with a pure Schawlow–Townes exponential inside Widmann et al.’s fixed gray windows. But Eq. (3) gives the stretched-exponential temporal form only at \\(|\\delta r|=0\\), whereas the analyzed temporal cuts are identified in Figs. 1–3 as \\(|\\delta r|=a/\\sqrt2\\). At fixed nonzero \\(r_0\\), the KPZ prediction is the full scaling form in Eq. (8), \\(C_{\\theta\\theta}=t^{2\\beta}F(C_1r_0/t^{1/z})\\). Over a finite window this crosses between short- and long-time asymptotes and can appear curved on a \\(t^{2\\beta}\\) plot or be locally approximated by another power, particularly as finite-size effects begin.\n\nThus the WLS comparison establishes that the two pure asymptotic models favor exponential-Gaussian behavior, but not by itself that an intermediate KPZ regime is absent or statistically unnecessary. The full-map collapses provide important supporting evidence, but the central exclusion claim still leans on this potentially misspecified temporal model comparison. This is a correctness-risk issue in the model test, not a disagreement with KPZ consensus.","agreement_with_reader":"agree"},"referee_report":{"model":"moonshotai/kimi-k3","summary":"This Comment reanalyzes the experimental g^(1)(δr,δt) maps of Widmann et al. (Science 392, 221 (2026)), which reported KPZ universal scaling in a 2D polariton condensate lattice. The authors argue that within the space-time windows used in the original analysis, the temporal decay is exponential (Schawlow–Townes) and the spatial decay Gaussian, for all pump powers and both square and triangular lattices, supported by semi-log curvature tests (Figs. 1–3) and weighted least-squares residuals (Table I). They further show that the KPZ collapse reported in Ref. [1] is an artifact of omitting the normalization factor κ: with proper normalization the KPZ representation fails to collapse, while a β=1/2, χ=1 representation collapses cleanly (Figs. 8–11). Analytic toy datasets (Figs. 6–7) demonstrate that an incorrect κ can both destroy a genuine KPZ collapse and manufacture a spurious KPZ-like collapse from exponential-Gaussian data.","tokens_in":9735,"tokens_out":2484,"duration_ms":75334,"significance":"If correct, the Comment overturns the central claim of a high-profile Science paper and, equally important, identifies a general mechanism — a normalization offset 2 ln κ / t^{2β} — by which scaling collapses of coherence maps can be spuriously produced or destroyed. This is a falsifiable, methodologically portable point relevant to all KPZ experiments on driven-dissipative systems. The strengths are concrete: the reanalysis covers both lattice geometries and all available pump powers, uses model-insensitive curvature diagnostics, provides analytic control datasets (Figs. 6–7) that demonstrate both the destruction of a true KPZ collapse and the fabrication of a fake one under wrong κ, and supplies full-map collapses in both representations with and without normalization (Figs. 4–5, 10–11). The toy-model construction reproducing the qualitative features of Ref. [1]'s Fig. 3B from non-KPZ data is a genuinely sharp argument.","major_comments":[{"comment":"Sec. II and Table I: the temporal fits compare a pure stretched exponential (the |δr|=0 asymptote of Eq. (3)) against a pure exponential, but the analyzed temporal cuts (Figs. 1–3) are taken at |δr|=a/√2, not zero. At fixed nonzero separation the KPZ prediction is the crossover form of Eq. (8), t^{2β}F(C1 r0/t^{1/z}), which over a finite window is not a stretched exponential and can curve on a t^{2β} semilog plot. The full-map collapses (Figs. 4, 10, 11) do address the full scaling form and substantially mitigate this, but Table I as presented only excludes the asymptotic model. The authors should either fit the full form (8) to the temporal cut or state explicitly why the asymptotic comparison is adequate within the gray windows.","section":"§II, Table I"},{"comment":"Table I: no degrees of freedom, fit-parameter counts, or weight definitions are given for the WLS values, so the phrase 'systematically and significantly larger' cannot be assessed as a statistical statement. The triangular-lattice temporal row (204.6 vs 125.5) has both residuals very large relative to the square-lattice values (12.97 vs 4.07), suggesting neither model fits that cut well; reduced chi-square values (or residuals plots) for each fit are needed to support the exclusion claim, particularly since this is the load-bearing quantitative evidence in Sec. II.","section":"Table I"},{"comment":"Sec. IV B and Figs. 8–9: the procedure determining κ needs to be stated precisely and reproducibly. The caption of Fig. 8 indicates κ is set by the δt→0 extrapolation of the temporal fit within the KPZ window, while Sec. I B defines it via g_fit(0,0)=1/κ. It should be made explicit (i) which fit (stretched exponential or exponential) is used to set κ in each representation, (ii) that the same κ is used when comparing representations (i) and (ii), and (iii) how sensitive the collapse quality in panels b of Figs. 10–11 is to the κ value. Fairness of the (i)-vs-(ii) comparison hinges on this.","section":"§IV B, Figs. 8–9"}],"minor_comments":[{"comment":"Captions of Figs. 8 and 9: the panel lettering in the caption text ('obtained b using the KPZ exponents and without normalization, c ... with normalization, d using β=0.5, χ=1') appears offset by one relative to the panels described in Sec. IV B (a: no normalization, b: normalized, c: exponential-Gaussian). Please reconcile.","section":"Figs. 8–9 captions"},{"comment":"Typo in Conclusion: 'Scahwlow-Townes' should be 'Schawlow–Townes' (also 'Shawlow-Townes' in the Fig. 8/9 captions).","section":"§V"},{"comment":"Sec. IV A: the phrase 'hide the true features of a dataset and mislead for alien ones' is unclear; please rephrase (e.g. 'and mimic features of a different universality class').","section":"§IV A"},{"comment":"Sec. IV B: the authors note that Ref. [1] discarded certain data points within the gray windows while the Comment uses all points. It would help the reader to mark (e.g. by symbol or color) which points were excluded in Ref. [1] in Figs. 8–11, so the effect of that selection can be judged directly.","section":"§IV B"},{"comment":"Eq. (7) contains a stray extra parenthesis in 'F(C1|δr|/δt^{1/z}))'; also the rendering of g^{(1)} is inconsistent between the abstract and main text.","section":"Eq. (7)"}],"recommendation":"minor_revision","confidential_remarks":"Several authors of this Comment (Bloch, Ravets, Fontaine, Minguzzi, Canet) are authors of the Nature 608, 687 (2022) paper reporting KPZ scaling in 1D polaritons and of the FRG calculation of the 2D scaling function used here as a reference curve. This does not affect the technical assessment, but the editor may wish to ensure the chosen second referee has no involvement in either the original Science paper or the 2022 Nature paper, and that a Reply from Widmann et al. is solicited in the usual way for Comments. The scientific question — correct normalization practice for scaling collapses of g^(1) maps — is of broad methodological interest beyond this dispute."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"The one thing to know is that this comment does the unglamorous work of re-fitting the released Widmann et al. coherence maps and shows, pretty cleanly, that inside those gray windows the decays look exponential in time and Gaussian in space for every pump and both lattices. The KPZ-looking collapse in the Science paper largely disappears once you normalize with a proper κ; with wrong κ you can even fake a KPZ asymptote on pure expo–Gauss toy data. That is the real contribution.\n\nWhat they do well: side-by-side semi-log and curvature plots, WLS residuals, multi-power and dual-lattice checks, analytic counter-examples on κ, and full-map collapses with and without normalization (including the appendix). The theory section is standard Altman/Fontaine material, used correctly—not reinvented. Circularity is low; they are arguing about someone else’s public maps.\n\nSoft spots, in proportion. The pure stretched-exponential vs Schawlow–Townes comparison in Table I is slightly misspecified: the temporal cuts sit at |δr|=a/√2, not zero, so finite-offset KPZ is a crossover form, not a pure t^{2β} line. That weakens the WLS line-shape test alone. It does not sink the paper—the full space-time collapses under proper κ are the stronger evidence, and those still favor β=0.5, χ=1. Other limits are ordinary for a comment: fixed windows inherited from the original, no shipped analysis code, dependence on released products. They do not claim KPZ is impossible in these systems, only that it is not justified in the windows and analysis of the Science paper.\n\nWho it is for: anyone citing or following 2D polariton KPZ claims, and people who care about collapse hygiene. It deserves a serious referee, not a desk reject. I would engage—read it, and if you work this area, cite the correction when you discuss Widmann.","headline":"Solid public reanalysis: Widmann’s KPZ collapse is mostly a normalization artifact; the data prefer exponential–Gaussian over the windows they actually used.","tokens_in":10882,"tokens_out":506,"would_cite":true,"duration_ms":18545,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"Reanalysis finds polariton coherence decays exponentially in time and Gaussian in space, not with KPZ stretched exponentials.","keywords":["Kardar-Parisi-Zhang","polariton condensate","first-order coherence","Schawlow-Townes","data collapse","normalization","driven-dissipative","two-dimensional scaling"],"falsifier":"A re-fit of the same public data sets inside the identical gray-shaded windows that recovers lower residuals for KPZ stretched exponentials than for exponential/Gaussian forms, or a properly normalized collapse onto the KPZ scaling function that remains tight for all pump powers.","tokens_in":10765,"feed_emoji":"ₐ","tokens_out":908,"duration_ms":16632,"temperature":0.7,"pith_summary":"This comment re-examines interferometry data on a two-dimensional polariton condensate that were claimed to show Kardar–Parisi–Zhang (KPZ) universal scaling in the decay of first-order coherence. Over the same space-time windows used in the original analysis, and for both square and triangular lattices at every reported pump power, the measured coherence instead follows a simple exponential decay in time (Schawlow–Townes) and a Gaussian decay in space. With the corresponding exponents β = 0.5 and χ = 1, and after proper normalization that removes a short-time non-universal offset, the full space-time maps collapse cleanly onto one non-KPZ curve. The apparent collapse onto the KPZ scaling function is shown to be an artifact of incorrect normalization: when the same data are plotted without that artifact, or with the correct normalization under KPZ exponents, the collapse fails. The central claim of KPZ universal scaling in those windows is therefore not supported by the data.","feed_headline":"Polariton data show exponential, not KPZ, coherence decay","feed_subtitle":"Reanalysis finds the reported KPZ collapse is an artifact of incorrect normalization","key_machinery":"Proper normalization of g^(1) by the factor κ that forces the extrapolated fit through unity at the origin, together with weighted least-squares comparison of pure stretched-exponential (KPZ) versus pure exponential/Gaussian forms and the resulting quality of collapse under the two sets of exponents.","core_discovery":"Over the space-time windows analyzed in the original work, |g^(1)(δr, δt)| exhibits exponential temporal and Gaussian spatial decay for all pump powers and both lattice geometries; the reported data collapse onto the KPZ scaling function is an artifact of incorrect normalization, so KPZ universal scaling is not the appropriate description of those measurements.","pith_inferences":["The same normalization artifact could affect other reported KPZ collapses in driven-dissipative condensates that skip the short-time offset.","If finite-size Schawlow–Townes physics already dominates inside the chosen windows, larger samples or shorter-time probes would be required to expose any intermediate KPZ regime.","A mixed model that interpolates from non-universal short-range coherence through a possible KPZ window into long-time exponential decay could still be tested once the pure forms are properly normalized."],"forward_implications":["Claims of two-dimensional KPZ scaling in polariton coherence must be re-checked with the correct short-time normalization before being accepted.","Exponential (Schawlow–Townes) temporal decay is the operative description over the reported experimental windows.","Gaussian spatial decay with χ = 1, not the KPZ roughness exponent, organizes the spatial data.","Future collapse analyses of condensate coherence will need to treat the non-universal offset κ explicitly or risk spurious scaling."],"fun_headline_variants":["Reanalysis finds Gaussian spatial, exponential temporal polariton decays","KPZ collapse artifact: polariton data fit exponential not KPZ scaling","Comment: polariton coherence shows no KPZ scaling in analyzed windows","Incorrect normalization created false KPZ collapse in polariton data","Polariton |g^(1)| decays Gaussian in space, exponential in time"],"cache_read_input_tokens":128,"weakest_assumption_plain":"That the fixed windows taken from the original paper, plus a direct comparison of pure KPZ stretched exponentials against pure exponential/Gaussian forms under correct normalization, are enough to rule out KPZ scaling inside those same windows.","fun_headline_variants_meta":{"raw":{"variants":["Reanalysis finds Gaussian spatial, exponential temporal polariton decays","KPZ collapse artifact: polariton data fit exponential not KPZ scaling","Comment: polariton coherence shows no KPZ scaling in analyzed windows","Incorrect normalization created false KPZ collapse in polariton data","Polariton |g^(1)| decays Gaussian in space, exponential in time"]},"model":"grok-4.5","effort":"low","cost_usd":0.002237,"raw_usage":{"total_tokens":990,"prompt_tokens":817,"num_sources_used":0,"completion_tokens":73,"cost_in_usd_ticks":22368000,"prompt_tokens_details":{"text_tokens":817,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":100,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":817,"tokens_out":73,"duration_ms":3728,"temperature":1.0,"reasoning_tokens":100,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-31T22:25:54.363151+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"A re-fit of the same public data sets inside the identical gray-shaded windows that recovers lower residuals for KPZ stretched exponentials than for exponential/Gaussian forms, or a properly normalized collapse onto the KPZ scaling function that remains tight for all pump powers.","supporting_citations":[],"review_version":1}