{"id":"9318f282-5026-4060-953f-2fab8d4baf0f","arxiv_id":"2606.30468","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":7.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"First experimental verification of entanglement that persists under arbitrary orthonormal mode transformations, generated via temporally multiplexed interferometer and certified by tailored quantum-state tomography.","lead":"The paper reports the first experimental demonstration of mode-independent entanglement using heralded two-photon states from a reconfigurable interferometer. This form of entanglement could improve robustness in quantum communication under noise or with untrusted parties.","discovery_kind":"unclear","skeptic_critique":{"model":"grok-4.3","headline":"Certification shows high fidelity to |1,1> in one basis but does not bound entanglement over all mode transformations","rationale":"The reader's weakest assumption directly identifies the unverified step: that the generated state satisfies the all-basis entanglement property. The proposed check converts that assumption into a single, falsifiable computation on the existing tomography data.","tokens_in":1623,"tokens_out":289,"duration_ms":29442,"concrete_test":"From the reconstructed two-mode density matrix in the original basis, numerically sample 200 random SU(2) transformations, apply each to the state, and compute logarithmic negativity; if the minimum over the sample is >0.05, the claim is supported; otherwise recompute with denser sampling or analytic bound.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim requires the heralded state to remain entangled under arbitrary orthonormal mode redefinitions. The experiment generates a state via temporally multiplexed interferometer and measurement-induced nonlinearities, then performs tailored tomography in a fixed basis to report high fidelity to the ideal |1,1> state. Because any deviation (loss, higher-photon components, or mode mismatch) can make the state separable for some rotation angle, fidelity in one basis alone does not guarantee positivity of an entanglement monotone for every unitary on the mode space. No explicit minimization of negativity or concurrence over the continuous family of bases is described.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript reports the first experimental realization of mode-independent (or 'unpartible') entanglement in heralded two-photon states. Using a fully reconfigurable temporally multiplexed interferometer with measurement-induced nonlinearities, the authors generate states claimed to remain entangled for every choice of orthonormal mode basis. Certification is performed via tailored quantum-state tomography that yields fidelities validating the presence of this resilient entanglement, with potential benefits for quantum communication in noisy or untrusted settings.","tokens_in":1728,"tokens_out":489,"duration_ms":35780,"significance":"If the central claim is rigorously established, the work would introduce a qualitatively stronger form of entanglement that does not rely on a pre-fixed mode basis, offering operational robustness beyond conventional party-dependent entanglement. The reconfigurable temporally multiplexed platform itself constitutes a technical contribution for generating such states. The current manuscript, however, provides insufficient evidence that the experimental imperfections are small enough to preserve entanglement under arbitrary basis transformations.","major_comments":[{"comment":"Abstract and certification process: The claim that the generated states 'are entangled for all choices of orthonormal mode basis' rests on fidelities obtained from tailored quantum-state tomography. No explicit calculation or bound is presented showing that an entanglement monotone (e.g., negativity or concurrence) remains positive for every unitary transformation on the two-mode space. Fidelity to the ideal |1,1> state in a single fixed basis does not by itself exclude the possibility that small admixtures of |2,0> or |0,2> components render the state separable for some rotation angle.","section":"Abstract / certification process"},{"comment":"State generation section: The heralded two-photon states are produced via measurement-induced nonlinearities in the temporally multiplexed interferometer. Without reported quantitative upper bounds on multi-photon components, loss rates, or mode mismatch (e.g., via measured g^(2) or higher-order correlation functions), it is impossible to verify that the experimental state lies inside the region of the two-photon subspace where entanglement is guaranteed for all bases.","section":"State generation"}],"minor_comments":[{"comment":"The title uses 'unpartible entanglement' while the abstract uses 'mode-independent entanglement'; consistent terminology would improve clarity.","section":"Title / Abstract"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for their thorough review and for acknowledging the potential significance of mode-independent entanglement. We address each major comment below and will revise the manuscript to provide the requested explicit calculations and quantitative bounds.","responses":[{"response":"We agree that fidelity in a single basis alone is insufficient and that an explicit demonstration via an entanglement monotone is necessary. The tailored QST reconstructs the full two-photon density matrix in a manner that permits this verification. In the revised manuscript we will add a calculation of negativity (or concurrence) as a function of arbitrary orthonormal basis rotation, using the measured state and its error bars, to confirm it remains positive for all angles.","revision_made":"yes","referee_comment":"[Abstract / certification process] Abstract and certification process: The claim that the generated states 'are entangled for all choices of orthonormal mode basis' rests on fidelities obtained from tailored quantum-state tomography. No explicit calculation or bound is presented showing that an entanglement monotone (e.g., negativity or concurrence) remains positive for every unitary transformation on the two-mode space. Fidelity to the ideal |1,1> state in a single fixed basis does not by itself exclude the possibility that small admixtures of |2,0> or |0,2> components render the state separable for some rotation angle."},{"response":"We accept that quantitative bounds on imperfections are required to place the experimental state inside the region where mode-independent entanglement is guaranteed. The revised manuscript will report the measured g^(2)(0) values for the heralded photons, loss rates from the interferometer, and mode-mismatch estimates, together with an analysis showing that these imperfections keep the state within the two-photon subspace supporting the claimed property.","revision_made":"yes","referee_comment":"[State generation] State generation section: The heralded two-photon states are produced via measurement-induced nonlinearities in the temporally multiplexed interferometer. Without reported quantitative upper bounds on multi-photon components, loss rates, or mode mismatch (e.g., via measured g^(2) or higher-order correlation functions), it is impossible to verify that the experimental state lies inside the region of the two-photon subspace where entanglement is guaranteed for all bases."}],"tokens_in":1357,"tokens_out":477,"duration_ms":23360,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The central result is an experimental claim of mode-independent entanglement: a heralded two-photon state generated in a temporally multiplexed interferometer that is said to remain entangled no matter which orthonormal basis the modes are expressed in. The setup uses reconfigurable interferometry and measurement-induced nonlinearities to produce the state, followed by tailored tomography that reports high fidelity to the ideal |1,1> state.\n\nThe generation method itself is the clearest technical contribution. Building a fully reconfigurable temporal multiplexer that can produce heralded pairs with the required symmetry is non-trivial, and the abstract indicates they achieved usable rates and fidelities. That part of the work looks solid on its own terms.\n\nThe soft spot is the certification of the stronger claim. Fidelity to |1,1> in a single fixed basis does not bound entanglement monotones under continuous families of basis changes. Small loss, higher-photon components, or mode mismatch can make the state separable for some rotation angle even when it looks good in the measurement basis. The abstract mentions no explicit minimization of negativity or concurrence over the space of unitaries, nor any worst-case bound derived from the observed imperfections. Without that step the main claim rests on the assumption that the generated state is close enough to ideal that the property holds automatically.\n\nThe paper is aimed at experimental groups working on robust quantum resources for communication in noisy or untrusted settings. A reader interested in the interferometer architecture or the general idea of basis-independent correlations could extract useful technical details. It is coherent enough on its own terms to merit referee time, though the referees would need to see the full tomography data and any additional checks on basis independence before the central claim can be accepted.","headline":"The paper demonstrates a two-photon state with high fidelity to |1,1> in one basis via a multiplexed interferometer, but the data shown do not establish that entanglement survives every orthonormal mode redefinition.","tokens_in":2196,"tokens_out":425,"would_cite":false,"duration_ms":22584,"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 two-photon quantum state remains entangled no matter which orthonormal modes define the parties.","keywords":["mode-independent entanglement","two-photon states","heralded photons","quantum state tomography","temporally multiplexed interferometer","quantum communication","entanglement certification"],"falsifier":"Performing tomography after an arbitrary orthonormal mode transformation and obtaining a fidelity below the threshold for entanglement in that basis would show the state is not mode-independent.","tokens_in":2530,"feed_emoji":"","tokens_out":535,"duration_ms":20799,"temperature":0.7,"pith_summary":"The paper shows an experimental realization of entanglement that does not depend on any fixed choice of modes. Standard entanglement can vanish if the parties are redefined, but the reported states stay entangled under every orthonormal transformation of the mode basis. This property protects the correlation against the kind of mixing that occurs in real channels or with untrusted devices. The authors produce the states with a reconfigurable temporally multiplexed interferometer and confirm the property through quantum-state tomography that yields high fidelity for multiple bases.","feed_headline":"Two-photon entanglement survives any mode transformation","feed_subtitle":"Heralded states remain entangled under every orthonormal basis change, shielding against noise and basis mismatch","key_machinery":"A fully reconfigurable temporally multiplexed interferometer with measurement-induced nonlinearities that generates the heralded two-photon states.","core_discovery":"The experiment produces heralded two-photon states in two modes that are entangled for all choices of orthonormal mode basis, verified by tailored quantum-state tomography achieving fidelities that confirm the presence of mode-independent entanglement.","pith_inferences":["Protocols could be designed that distribute entanglement without requiring the sender and receiver to agree on a shared mode basis in advance.","The same independence might be checked experimentally in continuous-variable or multi-photon systems where mode mixing is also common.","If heralding efficiency can be increased, the approach could be scaled to states with more than two photons while preserving the basis independence."],"forward_implications":["The entanglement remains intact when the parties are redefined by any orthonormal transformation.","The correlation is protected in settings with noise or untrusted parties that alter the effective modes.","Tailored tomography suffices to certify the resilient correlation across bases.","The generation method supplies a concrete route to operationally advantageous quantum states."],"fun_headline_variants":["Two-photon entanglement in all mode bases verified","Mode-independent entanglement shown with heralded photons","Entanglement holds for every orthonormal mode basis","Experimental unpartible entanglement in two modes","Heralded two-photon states entangled regardless of basis"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The heralded two-photon states are entangled for every possible orthonormal choice of mode basis.","fun_headline_variants_meta":{"raw":{"variants":["Two-photon entanglement in all mode bases verified","Mode-independent entanglement shown with heralded photons","Entanglement holds for every orthonormal mode basis","Experimental unpartible entanglement in two modes","Heralded two-photon states entangled regardless of basis"]},"model":"grok-4.3","cost_usd":0.004449,"raw_usage":{"total_tokens":2164,"prompt_tokens":554,"num_sources_used":0,"completion_tokens":66,"cost_in_usd_ticks":44487000,"prompt_tokens_details":{"text_tokens":554,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":1544,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":554,"tokens_out":66,"duration_ms":14660,"temperature":1.0,"reasoning_tokens":1544,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-30T06:08:42.716487+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Performing tomography after an arbitrary orthonormal mode transformation and obtaining a fidelity below the threshold for entanglement in that basis would show the state is not mode-independent.","supporting_citations":[],"review_version":1}