{"id":"e9586877-6af7-4789-af4b-4b4698ec7ed2","arxiv_id":"2507.10366","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":4,"one_line_summary":"A short tip pulse at the edge of a nu=1/3 Laughlin droplet excites edge modes and bulk magnetoroton excitations, with the balance controlled by pulse position, duration, and strength.","lead":"A numerical simulation of a fractional quantum Hall liquid shows that a short voltage pulse at the edge sends excitations along the edge and into the bulk, with bulk motion dominated by magnetoroton modes. The result offers a microscopic model for recent time-resolved pump-probe experiments on quantum Hall edges.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"V1-only dynamics has zero edge velocity, so the claimed edge propagation and the match to chiral-edge experiments rest on an unverified Coulomb assertion.","rationale":"The reader's weakest assumption correctly identifies the zero edge velocity of the pure V1 model as the point where the central claim is least secure. The paper's own text states that under V1 the tip potential does not propagate along the boundary, yet the abstract and conclusions claim edge propagation and agreement with chiral-edge pump-probe experiments. The Coulomb-interaction paragraph is a single unquantified sentence, so the comparison to Refs. 44-46 is unsupported. I agree with the reader that this is the load-bearing gap. I also note the printed time-evolution equations, Eqs. (5) and (6), are dimensionally wrong as written—the evolution operator should act at fixed tau and t, not be integrated over the evolution time—but this is likely a typographical error if the time-dependent Lanczos calculation was implemented correctly. The more substantive issue remains the V1 model. The fidelity analysis and the alignment of Sbulk with the density maximum are internally plausible and give the paper value as a model-study, but they do not establish the experimental connection unless confirmed with Coulomb dynamics. The verdict should remain conditional: the claimed physics may survive, but the missing Coulomb time-resolved calculation is required before accepting the central claim.","tokens_in":12915,"tokens_out":5475,"duration_ms":66525,"concrete_test":"Run the same quench for Ne=9, Norb=27 with the LLL-projected Coulomb interaction (or V1 plus a small V3 term to give a nonzero edge velocity), with U_delta=1, tau=3, at w=5.4 and 7.0 lB. Compute the time-dependent residual density rho(r,theta,t) and the diagnostics Sbulk(w), Sedge(w), and f(t). If the density packet acquires azimuthal motion with nonzero velocity and the Sbulk(w) peak remains at r about 5.4 lB while Sedge(w) peaks near r about 6.4 lB, the V1 result is representative. If the edge packet propagates and shifts these peak positions or changes the Sbulk/Sedge ratio substantially, the central edge-bulk balance claim is an artifact of the V1 zero-velocity model.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim that the pulse excites density spreading 'both along the edge and into the bulk' is not supported by the model actually simulated. Section III uses the pure V1 short-range interaction, and the paper itself states that for V1 'the edge states are also zero energy eigenstates, and thus the edge velocity is zero. In this scenario, the impact of the tip potential does not propagate along the boundary.' Consequently, in Figs. 2–5 there is no chiral edge propagation: the edge sector cannot transport the pulse azimuthally. The only evidence that realistic interactions change this is one sentence asserting that with Coulomb interaction 'the overall qualitative behavior remains similar,' with no time-resolved density maps, no Sbulk/Sedge curves, and no edge-velocity data. Since the experiments in Ref. 44 are about propagating edge magnetoplasmons, the claimed agreement is not established. The bulk-magnetoroton part may survive, but the edge-propagation half of the central claim—and the Sedge(w) peak at the dipole maximum—is conditioned on an unverified Coulomb calculation. This should be read as a V1-specific study unless that calculation is provided.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript studies the quench dynamics of a ν=1/3 Laughlin droplet in a disk geometry under a time-limited delta-function tip potential. The authors consider 9 electrons in 27 orbitals, evolve the system under the V1 short-range interaction during and after the pulse, and analyze the residual density, the fidelity, and the overlaps of the post-pulse state with eigenstates of the static Hamiltonian. They introduce Sbulk and Sedge to quantify the bulk and edge contributions, and report that the bulk contribution peaks when the tip sits at the electron density maximum (w ≈ 5.4 lB), while the edge contribution peaks at w ≈ 6.4 lB, coinciding with the maximum of the edge dipole moment. They further attribute the bulk excitation predominantly to magnetoroton modes and interpret the pulse-strength/duration dependence as Rabi-like oscillations. The paper claims qualitative agreement with recent pump-probe experiments on chiral edge magnetoplasmons and bulk magnetorotons.","tokens_in":13143,"tokens_out":5684,"duration_ms":66750,"significance":"If the central claims hold, the paper provides a useful microscopic description of how a localized edge pulse couples to bulk and edge excitations in a fractional quantum Hall droplet. The main strengths are that the numerical study is parameter-free (no fitting to the data it explains), that the fidelity oscillation frequencies are internally consistent with energy differences extracted from the same spectrum, and that the pulse-position dependence of Sbulk and Sedge offers concrete, falsifiable predictions for future experiments. However, the significance is currently limited by two issues: the printed time-evolution formulas are non-unitary and the central edge-propagation claim rests on an unverified assertion about the Coulomb interaction. The bulk-magnetoroton part of the paper is likely sound and publishable, but the edge-chiral-transport half of the claim needs either additional calculation or a substantial reframing.","major_comments":[{"comment":"The time evolution is printed as |Ψ(0)⟩ = ∫_0^τ dt exp(-iH2 t/ℏ)|Ψ1⟩ and |Ψ(t)⟩ = ∫_0^t dt′ exp(-iH1 t′/ℏ)|Ψ(0)⟩. These expressions are not unitary, do not conserve the norm, and have incorrect dimensions; the correct forms should be |Ψ(0)⟩ = exp(-iH2 τ/ℏ)|Ψ1⟩ and |Ψ(t)⟩ = exp(-iH1 t/ℏ)|Ψ(0)⟩. Because every subsequent quantity (density, fidelity, overlaps) is computed from these states, this is a load-bearing error. If the numerical code actually used the unitary propagators, the text must be corrected to match the code, and the authors should confirm that the reported results are unaffected.","section":"Section II, Eqs. (5) and (6)"},{"comment":"The residual density is defined as ρ(t) = ⟨Ψ(t)|Ψ(t)⟩ - ρ1. For a normalized many-body state, ⟨Ψ(t)|Ψ(t)⟩ = 1, so this expression cannot generate the spatially resolved density maps shown in Fig. 3. The definition should involve the electron density operator, e.g., ρ(r,t) = ⟨Ψ(t)|Σ_i δ(r-r_i)|Ψ(t)⟩ - ρ1(r). As printed, the paper's central observable is mathematically undefined, so this equation must be corrected before the results can be assessed.","section":"Section III, Eq. (7)"},{"comment":"The model actually simulated is the pure V1 hard-core interaction, and the paper explicitly states that for V1 the edge states are zero-energy eigenstates with zero edge velocity, so the tip impact does not propagate along the boundary. Yet the abstract and conclusions claim that excitations spread both along the edge and into the bulk, and that electrons move along the edge due to chiral edge modes. The only evidence that realistic Coulomb interaction changes this is a single paragraph asserting that the overall qualitative behavior remains similar, without showing any Coulomb-interaction density dynamics, Sbulk/Sedge curves, or edge-velocity data. Since the experiments in Refs. 44-46 concern propagating chiral edge magnetoplasmons, the edge-propagation half of the central claim is not supported by the presented simulation. The authors should either provide the Coulomb calculation or reframe the paper as a study of bulk diffusion and magnetoroton excitation in a zero-edge-velocity model.","section":"Section III, \"Effect of Coulomb interaction\", and Section V"}],"minor_comments":[{"comment":"The caption states that the penetration depth is \"significantly greater than that at w=7.0\", which is self-referential; it should compare case B (w=7.0) with case A (w=5.4) or otherwise be reworded.","section":"Fig. 3 caption"},{"comment":"The heading \"ANALYZE OF THE DETAILS OF THE TIP\" should be corrected to \"Analysis of the details of the tip\".","section":"Section IV heading"},{"comment":"The phrase \"magnetic rotor\" appears in the conclusions and elsewhere; this should be \"magnetoroton\".","section":"Throughout"},{"comment":"The text states that the magnetoroton subspace corresponds to angular momenta in the range [M0-Ne, M0], but the sum in Eq. (9) runs only up to M0-1. Please clarify the exact window used in the numerical calculation.","section":"Section III, Eq. (9)"},{"comment":"The claim about Coulomb interaction contains no quantitative data or figure. If this claim is retained, the authors should provide the system size, the relevant energy gaps, and a comparison of fidelity periods for the Coulomb case.","section":"Section III, \"Effect of Coulomb interaction\""},{"comment":"The paper credits the time-dependent Lanczos algorithm in the acknowledgments but gives no numerical details (time step, truncation, convergence criteria). A brief description of the numerical integration would help reproducibility.","section":"Section II"},{"comment":"The frequency peaks in Fig. 5(b) are read from the same eigenstates and energies that define the overlaps in Fig. 4, so the agreement in Table I is an internal consistency check rather than an independent prediction; this should be stated explicitly.","section":"Fig. 5(b) and Table I"}],"recommendation":"major_revision","confidential_remarks":"The core issue is the mismatch between the zero-edge-velocity V1 model and the paper's claims about chiral edge propagation and agreement with edge-magnetoplasmon experiments. If the authors can supply Coulomb-interaction results or significantly reframe the paper, the bulk-magnetoroton part may be publishable. The non-unitary definitions in Eqs. (5)-(7) must also be corrected before further review. I see no concerns about novelty or scope, but the current manuscript overclaims what the simulated model actually shows."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The paper does something genuinely new: it follows a time-limited tip pulse at the edge of a ν=1/3 Laughlin droplet and shows that the post-pulse state's composition depends on pulse position, with the bulk contribution peaking near the electron density maximum and the edge contribution peaking farther out. The fidelity analysis is internally consistent, and the match between Fourier peaks and energy differences from the same spectrum is a solid consistency check, though not an independent prediction. If the bulk-magnetoroton part is taken alone, the results are a reasonable numerical scenario.\n\nThe soft spots are real and load-bearing for the edge claims. The simulation uses the pure V1 interaction. As the authors themselves state in Section III, for V1 the edge states are zero-energy and the edge velocity is zero, so the impact of the tip potential does not propagate along the boundary. That means Figs. 2–5 contain no chiral edge propagation; the density changes are bulk diffusion only. The abstract and conclusions nevertheless claim excitations spread 'both along the edge and into the bulk' and 'align well with experimental observations.' That is not supported by the model actually simulated. The single sentence asserting that Coulomb interaction gives 'similar qualitative behavior' is not enough, especially when the experiments in Ref. 44 are about propagating chiral edge magnetoplasmons. This needs time-resolved density maps or at least Sbulk/Sedge curves for a Coulomb interaction before the edge-propagation half of the central claim is credible.\n\nAlso, Eqs. (5) and (6) are mathematically wrong as printed: they define the time-evolved state as an integral over time of the unitary evolution, which is not unitary. These look like typos, but they need fixing. The Sbulk definition is somewhat self-confirming: it sums overlaps only within the magnetoroton angular momentum window, so it labels those states as 'bulk' by construction. It is a reasonable operational choice, but it does not independently establish that those states are the dominant bulk excitations. The system is 9 electrons, and no code or data are released, so the numerics are not reproducible as is.\n\nWho is this for? Researchers studying edge-bulk coupling in FQH systems, especially those connecting to the recent pump-probe experiments. The bulk-magnetoroton part is worth a referee's time, but the edge-propagation claim needs a real Coulomb calculation. I would send it to review with the expectation of major revision, not reject it outright.\n\nRecommendation: engage with the paper, but only after the Coulomb calculation is provided and the printed errors are corrected.","headline":"A useful new numerical experiment undermined by overclaimed edge propagation: the V1 model has zero edge velocity, so the chiral-edge claims rest on an unverified Coulomb assertion.","tokens_in":13653,"tokens_out":2207,"would_cite":false,"duration_ms":26248,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["73.43.Lp","71.10.Pm"],"model":"deepseek-v4-flash","headline":"A time-limited tip pulse near the edge of a $\\nu=1/3$ Laughlin droplet sends the liquid into bulk magnetoroton excitations, with the edge-bulk mix controlled by pulse position.","keywords":["fractional quantum Hall effect","Laughlin state","edge magnetoplasmon","magnetoroton","quench dynamics","tip potential","exact diagonalization","fidelity oscillations"],"falsifier":"Repeat the exact-diagonalization pulse protocol with the Coulomb interaction, or on larger disks with $N_e=12,15$, and check whether the $S_{\\mathrm{bulk}}$ maximum still coincides with the radial electron-density maximum and the $S_{\\mathrm{edge}}$ maximum with the dipole-moment maximum, and whether the fidelity Fourier peaks still match the magnetoroton energy differences; a shift of the peak positions or a dominance of non-magnetoroton bulk states would contradict the central claim.","tokens_in":12726,"feed_emoji":"🧲","tokens_out":7972,"duration_ms":86806,"temperature":0.7,"pith_summary":"Starting from the $\\nu=1/3$ Laughlin ground state in a disk, the paper applies a $\\delta$-function tip potential near the edge for a finite duration, then removes it and follows the time evolution. It finds that the pulse excites both edge states and bulk states, and that the bulk part is dominated by neutral magnetoroton excitations rather than by generic quasiparticles. The central quantitative result is that the bulk contribution $S_{\\mathrm{bulk}}$ peaks when the tip sits at the electron-density maximum $w\\approx 5.4\\,\\ell_B$, while the edge contribution $S_{\\mathrm{edge}}$ peaks at $w\\approx 6.4\\,\\ell_B$, coinciding with the maximum of the edge dipole moment. These peak positions tie the edge-bulk balance of the pump-probe response to a geometric property of the edge, and the fidelity oscillations are shown to be governed by magnetoroton energy differences. The study matters because it offers a microscopic picture of how a localized voltage pulse at a fractional quantum Hall edge deposits energy into the gapped bulk, a process seen in recent pump-probe experiments.","feed_headline":"Edge pulse pushes a quantum Hall liquid into bulk magnetoroton modes","feed_subtitle":"Where the tip sits decides the split: density peak for magnetorotons, dipole peak for edge waves.","key_machinery":"The machinery is exact time evolution of a lowest-Landau-level projected many-body Hamiltonian on a disk of $N_e=9$ electrons in $N_{\\mathrm{orb}}=27$ orbitals, with the $V_1$ Haldane pseudopotential interaction whose densest zero-energy ground state is the Laughlin state. The pulse is a projected $\\delta$-function potential $V(z)=U_\\delta\\,\\delta(z-w)$ held for duration $\\tau$. Two diagnostics carry the argument: the overlap sums $S_{\\mathrm{bulk}}$ and $S_{\\mathrm{edge}}$, which count how much of the post-pulse state lives in the bulk magnetoroton window versus the zero-energy edge sector, and the fidelity $f(t)=|\\langle\\Psi(0)|\\Psi(t)\\rangle|^2$, whose Fourier spectrum is compared directly with energy differences among the dominant excited states.","core_discovery":"The paper claims that a time-limited, spatially localized pulse at the edge of a $\\nu=1/3$ Laughlin droplet acts as a pump that injects the liquid into two competing channels: edge excitations and bulk excitations. Within the $V_1$ model Hamiltonian, where edge states are exactly zero-energy and do not propagate along the boundary, the post-pulse state has significant overlap with the low-energy bulk states in the angular-momentum window $[M_0-N_e, M_0-1]$, and those states lie on the magnetoroton branch; the highest-overlap levels match the magnetoroton spectrum, and the energy differences among them reproduce the Fourier peaks of the time-dependent fidelity. The paper also establishes that the relative weight of the two channels is controlled by the pulse position: $S_{\\mathrm{bulk}}$ is maximal at the radial electron-density peak, whereas $S_{\\mathrm{edge}}$ is maximal where the edge dipole moment is maximal. For pulse strength and duration, the ground-state return amplitude oscillates as a two-level Rabi process with $\\Delta U_\\delta \\cdot \\tau = 2\\pi$, allowing the excitation to be tuned by pulse shaping. The authors argue that the same qualitative behavior survives with Coulomb interaction, where the edge velocity becomes nonzero.","pith_inferences":["The paper leaves implicit that the coincidence between $S_{\\mathrm{edge}}$ and the edge dipole moment suggests a general selection rule: a local probe couples most strongly to edge charge asymmetry; this could be tested at other fillings such as $\\nu=2/3$ where upstream edge modes exist.","With Coulomb interaction the edge velocity becomes nonzero, so the chiral drift of the excited packet is expected to shift the apparent $S_{\\mathrm{edge}}$ distribution in time; the $V_1$ result should be viewed as the zero-velocity limit of a family of edge-bulk dynamics.","A natural extension is to replace the square pulse by shaped pulses, such as Gaussian or chirped pulses, to selectively populate a single magnetoroton level, exploiting the two-level Rabi structure the paper identifies.","Finite-size scaling of $S_{\\mathrm{bulk}}$ and $S_{\\mathrm{edge}}$ on larger disks would show whether the peak positions track the density and dipole maxima universally or drift with $N_e$."],"forward_implications":["Positioning the excitation tip at the electron-density maximum selectively pumps the bulk magnetoroton branch, so the density disturbance diffuses inward from the edge on a timescale set by magnetoroton gaps.","Positioning the tip nearer the boundary selectively excites edge states, with maximum edge response at the dipole-moment maximum, so the edge-bulk mix is continuously tunable by pulse position.","Fourier analysis of the post-quench fidelity provides a dynamical spectroscopic route to magnetoroton energies: the oscillation frequencies equal energy differences between the dominant overlap states.","The Rabi-like relation $\\Delta U_\\delta\\,\\tau = 2\\pi$ lets pulse duration and strength suppress or enhance the return to the ground state, giving a practical tuning knob for pump-probe experiments."],"supporting_citations":[{"why":"Supplies the Laughlin wavefunction at $\\nu=1/3$ that is the initial ground state and the object the pulse perturbs.","marker":"[2]"},{"why":"Defines the Haldane pseudopotential formalism used to write the $V_1$ short-range interaction.","marker":"[48]"},{"why":"Introduces the single-mode approximation and the neutral magnetoroton excitation that the paper identifies as the dominant bulk mode.","marker":"[10]"},{"why":"Reports the pump-probe reflectance experiment on $\\nu=1/3$ edge magnetoplasmons whose pulse protocol this model mimics.","marker":"[44]"},{"why":"Reports time-resolved photoluminescence imaging of bulk magnetoroton and strain pulses, the experimental comparison for bulk diffusion.","marker":"[45]"},{"why":"Establishes that neutral magnetoroton excitations live in the zero center-of-mass angular-momentum subspace used to select bulk states.","marker":"[52]"},{"why":"Relates the edge dipole moment to Hall viscosity and topological properties, grounding the coincidence between $S_{\\mathrm{edge}}$ and the dipole maximum.","marker":"[49]"},{"why":"Provides the composite-fermion interpretation of higher-energy bulk excitations that the paper assigns to magnetoroton transitions.","marker":"[53]"}],"fun_headline_variants":["Edge pulse spawns bulk magnetorotons in quantum Hall liquid","Pulse at edge drives quantum Hall liquid into magnetoroton modes","Bulk magnetorotons emerge from edge pulse on quantum Hall droplet","Tunable edge pulse splits quantum Hall response into edge and bulk","Edge pulse triggers magnetoroton excitations in fractional Hall liquid"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The central calculation uses an idealized short-range interaction for which edge states have exactly zero energy and zero edge velocity, so the pulse cannot propagate along the boundary in the model; the paper asserts, in a single sentence, that the Coulomb interaction leaves the overall qualitative behavior similar.","fun_headline_variants_meta":{"raw":{"variants":["Edge pulse spawns bulk magnetorotons in quantum Hall liquid","Pulse at edge drives quantum Hall liquid into magnetoroton modes","Bulk magnetorotons emerge from edge pulse on quantum Hall droplet","Tunable edge pulse splits quantum Hall response into edge and bulk","Edge pulse triggers magnetoroton excitations in fractional Hall liquid"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000245,"raw_usage":{"total_tokens":1543,"prompt_tokens":958,"completion_tokens":585,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":574,"completion_tokens_details":{"reasoning_tokens":494}},"tokens_in":574,"tokens_out":585,"duration_ms":6697,"temperature":1.0,"reasoning_tokens":494,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T17:32:29.691083+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Repeat the exact-diagonalization pulse protocol with the Coulomb interaction, or on larger disks with $N_e=12,15$, and check whether the $S_{\\mathrm{bulk}}$ maximum still coincides with the radial electron-density maximum and the $S_{\\mathrm{edge}}$ maximum with the dipole-moment maximum, and whether the fidelity Fourier peaks still match the magnetoroton energy differences; a shift of the peak positions or a dominance of non-magnetoroton bulk states would contradict the central claim.","supporting_citations":[{"cited_title":"Kamiyama , author M","cited_arxiv_id":null,"evidence_quote":"Reports the pump-probe reflectance experiment on $\\nu=1/3$ edge magnetoplasmons whose pulse protocol this model mimics."},{"cited_title":"Kamiyama , author M","cited_arxiv_id":null,"evidence_quote":"Reports time-resolved photoluminescence imaging of bulk magnetoroton and strain pulses, the experimental comparison for bulk diffusion."},{"cited_title":"Yang , author Q","cited_arxiv_id":null,"evidence_quote":"Establishes that neutral magnetoroton excitations live in the zero center-of-mass angular-momentum subspace used to select bulk states."},{"cited_title":"Yang , author S","cited_arxiv_id":null,"evidence_quote":"Provides the composite-fermion interpretation of higher-energy bulk excitations that the paper assigns to magnetoroton transitions."}],"review_version":1}