{"id":"a0546e13-65d9-4458-8fad-27705bf62d71","arxiv_id":"2509.04526","paper_version":1,"verdict":"UNVERDICTED","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"A guitar fitted with a MIDI pickup drives Moth's Actias quantum synth to sonify a qubit, with foot controllers for rotations and measurements.","lead":"This paper reports an electric guitar modified with a MIDI pickup and foot pedals to control a quantum synthesizer that sonifies a qubit. It is an instrument build report, not a scientific result.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Claimed per-string qubit mapping contradicts single-qubit implementation","rationale":"The reader's verdict of UNVERDICTED is appropriate because the paper is an instrument build report, not a scientific result with testable predictions. My concern is not about scientific validity but about internal consistency of the central claim. The paper's stated principle — quantising each guitar string — is not reflected in the described implementation, which uses a single qubit. This is a concrete, load-bearing mismatch because the paper's title and abstract promise a 'quantum guitar' based on quantising all strings; if the implementation does not do that, the paper's central description is misleading. However, this does not change the verdict: the work is still unverifiable as a research claim, and the reliability issue raised by the reader is also real but secondary to whether the conceptual framework matches the build. A concrete test can settle the mismatch by examining the actual qubit count and routing. If the paper is intended as an artistic/engineering report, the terminology should be clarified; if it intends a literal per-string quantisation, the current evidence is lacking. Thus I keep the reader's UNVERDICTED verdict but highlight a different weak point than the reader did.","tokens_in":4619,"tokens_out":4340,"duration_ms":44878,"concrete_test":"Reconstruct or ask for the MIDI/OSC routing between the Fishman pickup and Actias. Specifically: (1) play a chord (multiple strings) and observe whether Actias produces multiple simultaneous qubit events or collapses to a single qubit whose state is changed only by foot pedals; (2) inspect the Actias configuration used in the performances to determine the number of qubits available. If the system has only one qubit and no per-string mapping, the §2 claim of associating a qubit to each playable state fails.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central conceptual claim (Abstract and §2) is that 'a guitar string represents a wave, and by associating a qubit to each of its playable states we get a quantum wave' — i.e., quantising each string. Yet the entire instrument description (§3, Figs 5–6) implements exactly one qubit in Actias, controlled by two foot pedals and a foot switch. The guitar's MIDI output triggers/sonifies this single qubit; there is no per-string or per-note qubit allocation. If the mapping is one-qubit-per-playable-state, the current hardware/software does not implement it; if the system is intentionally just a single qubit, the 'quantising all strings' language is unsupported. This mismatch is internal: the paper's own description of the setup undermines its headline principle.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper describes the 'Quantum Guitar', an electric guitar augmented with a MIDI pickup, a sustainer pickup, foot-controlled expression pedals, a foot switch, and Moth's Actias quantum synthesizer, which sonifies a single qubit. The author claims that by associating a qubit to each playable state of a guitar string, the instrument realizes a 'quantisation of all strings', and that the instrument has proven versatile and reliable in live performances, including with the industrial band Black Tish. The paper is a non-technical system description, containing no mathematical derivation, no audio analysis, and no reproducible data, but includes a troubleshooting section and links to a demo video and performance pages.","tokens_in":4826,"tokens_out":4161,"duration_ms":44124,"significance":"If realized as described, the instrument is a creative contribution to quantum music: it enables a single musician to manipulate a qubit hands-free using foot pedals while maintaining full classical guitar playability, and it offers a continuous quantum-classical sound transition. The explicit acknowledgment of hardware and software limitations is a positive feature. However, the scientific significance of the paper is limited by the absence of technical specifications and systematic evaluation, and the central conceptual claim of per-string quantisation is not implemented in the presented hardware.","major_comments":[{"comment":"The abstract and §2 claim that 'by associating a qubit to each of its playable states we obtain a quantum wave, i.e. quantisation of a guitar by means of quantising its strings.' Yet the implementation in §3 uses exactly one qubit in Actias, controlled by two foot pedals and a foot switch, and the text explicitly states 'we are working with a single qubit'. There is no per-string or per-playable-state allocation of qubits in the hardware or software. If the intended claim is that the guitar is an interface to a single qubit, the 'quantising all strings' language is unsupported; if the intended claim is per-string quantisation, the implementation does not realize it. This mismatch undermines the headline conceptual contribution.","section":"Abstract and §2 vs. §3, Figs. 5–6"},{"comment":"The abstract and §1 describe the instrument as 'very uniquely versatile and reliable' and a 'battle-ready axe', but §4 lists several reliability failures: Actias 'sometimes looses its preset', unplugging and replugging 'sometimes requires deleting an external midi device', and 'Having everything on one laptop doesn't function reliably'. The evidence for reliability is anecdotal, based on the author's own performances and a YouTube link, with no systematic test logs, failure statistics, or independent evaluation. The reliability claim should be either tempered to reflect the troubleshooting data or supported by a more rigorous evaluation protocol.","section":"§1 and §4"},{"comment":"The paper does not specify whether the 'qubit' in Moth's Actias is implemented on actual quantum hardware or simulated on a classical computer. The scientific content of the 'quantum guitar' depends on this distinction. If the qubit is simulated, the paper should explain what genuine quantum feature (e.g., superposition or interference) is retained and whether the sound synthesis itself is quantum or merely controlled by a quantum process. Without this clarification, the term 'quantum' in the central claim is ambiguous.","section":"§3 (and throughout)"}],"minor_comments":[{"comment":"The section title 'Relases' should be 'Releases'.","section":"§7 title"},{"comment":"'looses its preset' should be 'loses its preset'.","section":"§4"},{"comment":"'electro-accoustic' should be 'electroacoustic'.","section":"Introduction"},{"comment":"'at and TUM's International Quantum Forum' should be 'at TUM's International Quantum Forum' or 'at the TUM International Quantum Forum'.","section":"Acknowledgements"},{"comment":"The discussion of the 'third qubit rotation' and the statement that 'green' is 'not supposed to change the state' is confusing, especially since Figure 6's caption says 'green' and 'orange' cannot be used independently. Please rewrite for clarity and ensure the colors are legible in the figure.","section":"§3 and Fig. 6"}],"recommendation":"major_revision","confidential_remarks":"The paper is closer to an artistic/technical description than a conventional quant-ph research paper. The main conceptual claim (per-string quantisation) is not what the hardware implements, and the reliability claim is not backed by data. These issues are fixable by revising the claims to match the actual single-qubit setup and by softening reliability statements, but as written the paper would not meet the evidentiary bar of a refereed physics journal. If the authors decline to make such revisions, the paper might be better suited to an arts-technology or music-interface venue."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear colleague,\n\nThis is a fun, honest instrument-build report, not a physics paper—and its headline claim about \"quantising all strings\" is contradicted by the actual single-qubit setup. If you're expecting a research result, there isn't one: no derivations, no data, no reproducibility, just a demo video and a list of performances.\n\nWhat's genuinely new: the hands-free control scheme. A MIDI-equipped guitar drives Moth's Actias quantum synth, with foot pedals for qubit rotations, a foot switch for measurement, and two volume pedals to blend quantum and classical guitar sounds. That four-limb control idea is a real contribution to the quantum-instrument space, and the troubleshooting section is refreshingly candid (preset losses, MIDI device issues, two-laptop requirement). The paper also credits Q1Synth and prior quantum music work properly, so the citation pattern is fine.\n\nThe soft spot is load-bearing. The abstract says the instrument \"quantises all strings\" because \"a guitar string represents a wave\" and \"associating a qubit to each of its playable states.\" But the implementation uses exactly one qubit in Actias, controlled by two expression pedals and a foot switch. The guitar's MIDI pickup sends note information to that single qubit—there's no per-string or per-state qubit allocation. So the central principle as stated is not what was built. Either the design is a guitar-controlled single-qubit synth (which is still interesting, but the \"quantise all strings\" language is unsupported), or the design needs to actually allocate multiple qubits, and it doesn't. This mismatch is clear from the paper's own figures and Section 3.\n\nThe reliability claim also overreaches. The paper calls the instrument \"battle-ready\" and \"very uniquely versatile and reliable,\" then lists several failures and workarounds. Honest, but it undercuts the claim.\n\nWho gets value? People working on quantum music/art and instrument design might pick up ideas for their own builds. A physicist gets nothing. As a quant-ph preprint, this has no scientific claim to referee; it would be better placed in an arts/technology venue or as a project note. I would not send it to peer review in its current form—it needs either to drop the quasi-scientific framing or actually implement and measure the per-string qubit mapping.\n\nBest,\n[You]","headline":"A fun, honest instrument-build report, not a physics paper, and its 'quantise all strings' claim is contradicted by the single-qubit implementation.","tokens_in":5209,"tokens_out":3804,"would_cite":false,"duration_ms":39064,"reading_group":"maybe","serious_thinker":"no","would_accept_peer_review":false},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A guitar can be turned into a live-performance quantum instrument by attaching a qubit to each playable string state and controlling it with foot pedals.","keywords":["quantum guitar","qubit sonification","quantum music","Moth Actias","MIDI guitar","industrial music","quantum-classical transition","hands-free instrument"],"falsifier":"Log MIDI events and Actias state through a full live set under the paper's tech-rider conditions: a single mid-performance preset loss or a missed note-off while bending a string would refute the reliability claim.","tokens_in":4573,"feed_emoji":"🎸","tokens_out":4768,"duration_ms":53433,"temperature":0.7,"pith_summary":"The paper argues that quantising a guitar means associating a qubit with each playable state of a guitar string and using a quantum synth to sonify that qubit. Because the guitarist's hands are already busy, all quantum manipulations are moved to the feet, so a single seated musician can rotate and measure the qubit. The design keeps the ordinary guitar fully playable and adds a continuous dial between classical and quantum sound. The paper reports several live performances, including industrial music with Black Tish and a sonified Bell-pair piece with grand piano, as evidence that the instrument is versatile and battle-ready. If true, the significance is a hands-free template for turning familiar instruments into quantum instruments.","feed_headline":"Guitar strings become qubits, played with the feet","feed_subtitle":"A live-tested rig keeps full classical guitar sound while foot pedals rotate and measure the qubit.","key_machinery":"The qubit-per-string mapping is the load-bearing idea: each playable state of a guitar string is assigned a qubit, and Actias sonifies and displays that qubit. Rotations of the qubit are driven by two Boss EV-1-WL MIDI expression pedals, with an internal switch covering the third rotation; measurement is triggered by a Boss FS-6 foot switch in momentary mode; and Boss FV500 volume pedals independently control the classical and quantum signal levels. A Fernandes sustainer pickup (or, alternatively, long delay/reverb) lets notes ring continuously enough for the quantum sound. The foot-based control scheme is what keeps the musician's hands free for ordinary guitar playing.","core_discovery":"The central claim is that a guitar can become a working quantum musical instrument by mapping each playable state of a string to a qubit and sonifying that qubit with Moth's Actias quantum synth. The guitar retains all its classical sound and playability, while foot-controlled MIDI pedals rotate the qubit, a foot switch performs measurements, and two volume pedals let the musician blend continuously between pure classical guitar and quantum sound. Because all quantum controls use the feet, one seated musician can operate the full instrument. The author reports multiple live performances, including industrial music with Black Tish and a sonified Bell-pair performance with grand piano, and use","pith_inferences":["Extension: If the foot-controlled qubit interface proves stable across repeated live uses, the same controller scheme is a reusable template for hands-free quantum control of any instrument, not just guitar.","Extension: The paper's own troubleshooting list—Actias occasionally losing its preset, MIDI reconnection hiccups, and one-laptop unreliability—marks the boundary between a proven prototype and a fully dependable stage instrument; stabilising those is the direct next step.","Extension: The 'quantisation' here is a musical and control mapping rather than a physical quantisation of the string's vibrations, so the instrument's value is primarily as a new expressive interface and outreach tool, not as a test of quantum physics.","Extension: The paper's suggestion to add X-measurements as primitive operations, rather than requiring a rotation first, is a concrete, testable improvement that would likely make the instrument significantly easier to play."],"forward_implications":["The same hands-free, foot-controlled architecture can be copied to create Quantum Violin, Quantum Wind Instrument, and Quantum Percussion without sacrificing classical playability.","Smooth continuous transitions between quantum and classical sound become a live performance tool, useful for building tension or shifting texture mid-piece.","A single seated musician can play the full instrument because quantum controls require no hands, opening the way for one-person quantum ensembles.","The instrument has already been used in industrial music, with Black Tish recording an album entirely with it, and in a sonified Bell-pair composition with grand piano.","Planned pairings with cathedral organ require only the listed tech rider, suggesting the instrument can slot into existing performance logistics."],"supporting_citations":[{"why":"Supplies the Q1Synth quantum instrument on which Actias is based and which the paper extends with full foot-controlled qubit manipulation.","marker":"[7]"},{"why":"Provides the Bell-pair composition that pairs Quantum Guitar with grand piano and demonstrates the qubit-under-measurement use case.","marker":"[8]"},{"why":"Provides the ZX-calculus notation underlying the augmented music score used in performances like 'Bell'.","marker":"[9]"},{"why":"Establishes the prior quantum-composed music result that motivates building dedicated quantum instruments.","marker":"[1]"},{"why":"Defines the broader field of quantum computer music and frames the need for new instruments.","marker":"[2]"}],"fun_headline_variants":["Every guitar string is a qubit, and your feet play the quantum","This guitar turns each string into a qubit—control it with your feet","Quantum guitar: foot pedals turn classical strings into qubits","From blues to qubits: the quantum guitar you play with your feet","Play qubits with your feet: the live-tested quantum guitar"],"cache_read_input_tokens":2688,"weakest_assumption_plain":"The instrument's 'battle-ready' claim rests on the stability of the Actias quantum synth software and the MIDI pickup's tracking; the paper itself admits these sometimes lose presets or need reconnection, so if they fail on stage the central claim collapses.","fun_headline_variants_meta":{"raw":{"variants":["Every guitar string is a qubit, and your feet play the quantum","This guitar turns each string into a qubit—control it with your feet","Quantum guitar: foot pedals turn classical strings into qubits","From blues to qubits: the quantum guitar you play with your feet","Play qubits with your feet: the live-tested quantum guitar"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000627,"raw_usage":{"total_tokens":2724,"prompt_tokens":718,"completion_tokens":2006,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":462,"completion_tokens_details":{"reasoning_tokens":1912}},"tokens_in":462,"tokens_out":2006,"duration_ms":16135,"temperature":1.0,"reasoning_tokens":1912,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-05T10:50:24.838943+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Log MIDI events and Actias state through a full live set under the paper's tech-rider conditions: a single mid-performance preset loss or a missed note-off while bending a string would refute the reliability claim.","supporting_citations":[{"cited_title":"Q1synth: a quantum computer musical instrument","cited_arxiv_id":null,"evidence_quote":"Supplies the Q1Synth quantum instrument on which Actias is based and which the paper extends with full foot-controlled qubit manipulation."},{"cited_title":"Abdyssagin and B","cited_arxiv_id":null,"evidence_quote":"Provides the Bell-pair composition that pairs Quantum Guitar with grand piano and demonstrates the qubit-under-measurement use case."},{"cited_title":"A quantum natural language processing approach to musical intelligence","cited_arxiv_id":null,"evidence_quote":"Establishes the prior quantum-composed music result that motivates building dedicated quantum instruments."},{"cited_title":"Quantum Computer Music","cited_arxiv_id":null,"evidence_quote":"Defines the broader field of quantum computer music and frames the need for new instruments."}],"review_version":1}