{"id":"9df54ce5-c7c9-4f9e-b2ac-b4b76e018b71","arxiv_id":"2607.01653","paper_version":1,"verdict":"UNVERDICTED","confidence":"UNKNOWN","novelty_score":7.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"A hybrid feedback algorithm combining imaginary-time evolution and time-rescaling prepares the TFD ground state of the Maldacena-Qi model with near-unit fidelity.","lead":"The paper proposes a hybrid ITE-TR-FALQON quantum algorithm to prepare the thermofield double state of the two-coupled SYK model. Smart readers might care because this targets efficient preparation of entangled thermal states needed for quantum simulations of gravity models.","discovery_kind":"new_method","skeptic_critique":{"model":"grok-4.3","headline":"Central claim rests on noiseless classical numerics; hardware noise effects on non-unitary steps untested","rationale":"The reader's weakest assumption already isolates the simulation-to-hardware extrapolation as the critical unverified step; the above concern is a direct technical sharpening of that point rather than a new objection. No other internal inconsistency (e.g., in the definition of the protocol or the entropy observables) is visible from the supplied abstract and claim.","tokens_in":1748,"tokens_out":384,"duration_ms":17837,"concrete_test":"Take the smallest system size (N) at which the paper reports convergence to fidelity >0.99; re-run the ITE-TR-FALQON protocol under a depolarizing noise model with per-gate error 5e-4 (typical for current devices) and 1000 shots per measurement; if final fidelity falls below 0.9 or the Rényi entropy spectrum deviates by >5% from the exact TFD values, the hardware applicability of the central claim is not supported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The headline result (near-unit fidelity and accurate entropy spectra for the Maldacena-Qi TFD ground state) is demonstrated exclusively via classical simulation of the hybrid ITE-TR-FALQON protocol. The abstract states that non-unitary imaginary-time evolution is \"strictly necessary\" to break symmetry traps, yet the work supplies no analysis of how this non-unitary component is realized on hardware (ancilla-assisted circuits, post-selection, or variational approximations) nor any noisy simulation showing that the reported convergence and spectral accuracy survive realistic error rates. Because the kinetic limitations of unitary FALQON are already shown to be severe, any degradation of the non-unitary filtering step under noise would directly undermine the claim that the hybrid protocol succeeds where unitary methods fail.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The paper proposes a hybrid ITE-TR-FALQON protocol that augments time-rescaled feedback-based quantum algorithms with imaginary-time evolution to prepare the thermofield double ground state of the Maldacena-Qi (two coupled SYK) model. Classical numerical simulations are used to show that standard FALQON and TR-FALQON suffer severe kinetic limitations and symmetry traps when started from product states, while the hybrid method converges to near-unit fidelity and accurately reproduces the von Neumann and Rényi entropy spectra of the exact TFD state; non-unitary dynamics are claimed to be strictly necessary for filtering excited states.","tokens_in":1893,"tokens_out":573,"duration_ms":25212,"significance":"If the reported performance is reproducible and the non-unitary component can be realized on hardware, the work would supply a concrete algorithmic route to preparing highly entangled thermal states relevant to holographic models and many-body thermodynamics on quantum processors. The explicit demonstration that unitary feedback methods are kinetically limited in this system, together with the hybrid fix, offers useful design guidance even if the absolute performance numbers require further validation.","major_comments":[{"comment":"Abstract and numerical results: the headline claims of fidelities close to unity and high-precision entropy spectra are stated without any reported system sizes, qubit numbers, convergence thresholds, error bars, or post-selection rules, preventing assessment of whether the evidence supports the superiority of the hybrid protocol over unitary baselines.","section":"Abstract / Numerical results"},{"comment":"Discussion of non-unitary steps: the manuscript asserts that imaginary-time evolution is strictly necessary to escape symmetry traps (and that unitary FALQON fails), yet supplies no hardware-level implementation (ancilla-assisted circuits, post-selection overhead) nor any noisy simulation showing that the non-unitary filtering survives realistic error rates; this is load-bearing because the kinetic limitations of the unitary variants are already shown to be severe.","section":"Protocol description and numerical demonstrations"}],"minor_comments":[{"comment":"Define all acronyms (FALQON, TR-FALQON, ITE-FALQON, ITE-TR-FALQON) at first use and ensure consistent notation for the hybrid protocol throughout.","section":null},{"comment":"Clarify whether the reported entropy spectra are computed on the full system or reduced density matrix and specify the range of Rényi indices shown.","section":null}],"recommendation":"major_revision","confidential_remarks":"The manuscript sits at the boundary between hep-th and quantum information; the AdS2/wormhole motivation is clear but the algorithmic focus may fit better in a quantum-computing venue unless the holographic implications are strengthened."},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the careful reading and constructive comments on our manuscript. We address the major comments point by point below, indicating where revisions will be made to strengthen the presentation.","responses":[{"response":"We agree that explicit reporting of these parameters will improve clarity and allow better evaluation of the results. The classical simulations were performed on finite-size instances of the Maldacena-Qi model with a fixed number of sites (corresponding to a specific qubit count), using defined convergence criteria. In the revised manuscript we will update both the abstract and the numerical results section to state the system sizes, qubit numbers, convergence thresholds, any error bars, and post-selection rules employed.","revision_made":"yes","referee_comment":"[Abstract / Numerical results] Abstract and numerical results: the headline claims of fidelities close to unity and high-precision entropy spectra are stated without any reported system sizes, qubit numbers, convergence thresholds, error bars, or post-selection rules, preventing assessment of whether the evidence supports the superiority of the hybrid protocol over unitary baselines."},{"response":"The current work presents classical numerical evidence that unitary feedback methods encounter severe kinetic limitations and symmetry traps on this model, while the hybrid protocol succeeds. We acknowledge that the manuscript does not contain hardware implementations or noisy simulations. In the revision we will add a dedicated discussion of a possible ancilla-assisted circuit realization of the imaginary-time step, including an estimate of post-selection overhead, and we will comment on the implications for noisy devices. Comprehensive noisy simulations lie outside the scope of the present study but constitute a natural direction for follow-up work.","revision_made":"partial","referee_comment":"[Protocol description and numerical demonstrations] Discussion of non-unitary steps: the manuscript asserts that imaginary-time evolution is strictly necessary to escape symmetry traps (and that unitary FALQON fails), yet supplies no hardware-level implementation (ancilla-assisted circuits, post-selection overhead) nor any noisy simulation showing that the non-unitary filtering survives realistic error rates; this is load-bearing because the kinetic limitations of the unitary variants are already shown to be severe."}],"tokens_in":1424,"tokens_out":455,"duration_ms":21358,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The paper's core contribution is a hybrid feedback algorithm that combines imaginary-time evolution from ITE-FALQON with the time-rescaling of TR-FALQON. In the Maldacena-Qi model this beats the unitary-only versions, which get stuck in symmetry traps when started from product states. The numerics show the non-unitary component filters excited states and the rescaling speeds convergence, producing fidelities near one and entropy spectra that match the exact TFD state.\n\nThat combination is new and directly addresses documented kinetic limits of the parent methods. The authors are clear that non-unitary dynamics are required here, which is a useful observation for this specific system.\n\nThe main limitation is that all results come from noiseless classical simulation. The abstract states the non-unitary step is strictly necessary, yet there is no analysis of how that step would be realized on hardware or how it behaves under realistic error rates. If post-selection or ancilla-assisted circuits degrade the filtering, the reported advantage could shrink. System sizes, convergence tolerances, and error bars are also not detailed in the provided summary, which makes it hard to judge how far the method scales.\n\nThis work is aimed at people building quantum algorithms for holographic models or thermal-state preparation. It is concrete enough and grounded enough in the literature to merit a serious referee, even though the hardware robustness question will need addressing in revision.","headline":"The hybrid ITE-TR-FALQON protocol improves convergence on the Maldacena-Qi TFD ground state in classical simulations, but the non-unitary step remains untested under noise.","tokens_in":2427,"tokens_out":367,"would_cite":false,"duration_ms":11646,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"A hybrid protocol that adds imaginary-time evolution to time-rescaled feedback algorithms prepares the thermofield double ground state of the Maldacena-Qi model with near-unit fidelity from product states.","keywords":["thermofield double state","feedback quantum algorithms","Maldacena-Qi model","Sachdev-Ye-Kitaev model","imaginary time evolution","quantum gravity simulation","entanglement entropy"],"falsifier":"Running the hybrid ITE-TR-FALQON circuit on a physical quantum processor for the Maldacena-Qi Hamiltonian and directly measuring the overlap with the exact thermofield double state.","tokens_in":2645,"feed_emoji":"","tokens_out":689,"duration_ms":21455,"temperature":0.7,"pith_summary":"The paper establishes that standard feedback algorithms FALQON and TR-FALQON cannot reach the highly entangled ground state of the two coupled Sachdev-Ye-Kitaev model when started from trivial product states because they remain trapped by symmetries. Introducing non-unitary imaginary-time evolution breaks these traps and removes excited states, while time rescaling speeds convergence, so that the combined ITE-TR-FALQON method reaches the target thermofield double state. Numerical simulations confirm that the resulting state matches the exact von Neumann and Rényi entropy spectra and achieves fidelities close to unity. This preparation step is required for using quantum processors to simulate quantum gravity models that are dual to traversable wormholes.","feed_headline":"Hybrid feedback method prepares TFD state at near-unit fidelity","feed_subtitle":"Combining imaginary-time evolution with time-rescaled FALQON escapes symmetry traps in the Maldacena-Qi model and matches exact entropy spec","key_machinery":"The hybrid ITE-TR-FALQON protocol, which injects non-unitary imaginary-time evolution into a time-rescaled feedback loop to escape symmetry traps and filter excited states during ground-state preparation.","core_discovery":"The central claim is that the hybrid ITE-TR-FALQON protocol, formed by merging the imaginary-time evolution of ITE-FALQON with the time-rescaling mechanism of TR-FALQON, is both necessary and sufficient to prepare the thermofield double ground state of the Maldacena-Qi model from simple initial states, yielding fidelities near unity and reproducing the exact entropy spectra of the target state.","pith_inferences":["The same hybrid construction may allow feedback algorithms to prepare TFD states in other coupled SYK-like systems where unitary methods fail.","Implementing the non-unitary step on hardware will require ancillary qubits or measurement-based approximations not tested in the classical simulations.","Success for this wormhole dual suggests the protocol could be tested on larger lattices to check scaling of convergence time."],"forward_implications":["Non-unitary dynamics must be included to break symmetry traps that trap purely unitary feedback algorithms.","Time rescaling alone is insufficient without the imaginary-time component.","The prepared state reproduces both von Neumann and Rényi entropy spectra of the exact TFD state.","The method supplies a practical route to correlated thermal states needed for quantum simulations of AdS2 gravity."],"fun_headline_variants":["ITE-TR-FALQON prepares TFD state from trivial product states","Time rescaling speeds FALQON convergence to entangled ground state","ITE dynamics necessary to escape symmetry traps in Maldacena-Qi model","Hybrid protocol reproduces exact von Neumann entropy of TFD state"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The numerical evidence that non-unitary dynamics are strictly required and that the hybrid protocol converges will continue to hold when the circuit is executed on real quantum hardware rather than classical simulators.","fun_headline_variants_meta":{"raw":{"variants":["ITE-TR-FALQON prepares TFD state from trivial product states","Time rescaling speeds FALQON convergence to entangled ground state","ITE dynamics necessary to escape symmetry traps in Maldacena-Qi model","Hybrid protocol reproduces exact von Neumann entropy of TFD state"]},"model":"grok-4.3","cost_usd":0.006555,"raw_usage":{"total_tokens":3076,"prompt_tokens":693,"num_sources_used":0,"completion_tokens":73,"cost_in_usd_ticks":65549500,"prompt_tokens_details":{"text_tokens":693,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2310,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":693,"tokens_out":73,"duration_ms":18118,"temperature":1.0,"reasoning_tokens":2310,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-03T09:09:29.046697+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Running the hybrid ITE-TR-FALQON circuit on a physical quantum processor for the Maldacena-Qi Hamiltonian and directly measuring the overlap with the exact thermofield double state.","supporting_citations":[],"review_version":1}