pith. machine review for the scientific record. sign in

arxiv: 2605.08745 · v1 · submitted 2026-05-09 · 🪐 quant-ph

Recognition: no theorem link

Exclusion reshapes the operational manifestation of preparation contextuality

Authors on Pith no claims yet

Pith reviewed 2026-05-12 01:24 UTC · model grok-4.3

classification 🪐 quant-ph
keywords preparation contextualityparity-oblivious constraintsrandom exclusion codequantum advantagesemi-device-independent certificationqubit strategiesprepare-and-measurenoise robustness
0
0 comments X

The pith

Switching from retrieval to exclusion in parity-oblivious tasks lets qubits exceed the noncontextual bound on preparation contextuality.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that changing the operational task from retrieving information to excluding it alters how preparation contextuality appears under parity-oblivious constraints. In the smallest nontrivial case with three symbols, the optimal qubit strategy beats the tight bound obeyed by classical and preparation-noncontextual encodings, while the corresponding retrieval task shows no such advantage. This separation vanishes without the parity constraint. For any prime number of symbols the quantum gap grows linearly relative to the unconstrained exclusion gap, and the exact qubit performance yields a sharp semi-device-independent test for system dimension at least three. The protocol remains noise-robust enough for existing prepare-and-measure experiments.

Core claim

By introducing the parity-oblivious random exclusion code we show that classical and preparation-noncontextual encodings achieve a tight bound for any prime symbol size m. For the first nontrivial case of two digits and three symbols the derived exact qubit optimum exceeds this bound, producing a quantum advantage absent from parity-oblivious retrieval. For general prime m the qubit strategies generate a quantum-to-noncontextual gap that grows linearly with the gap of the unconstrained random exclusion code and supplies a sharp semi-device-independent certification of dimension d at least 3.

What carries the argument

The parity-oblivious random exclusion code (POREC), in which a sender prepares a quantum state so that a receiver can exclude one symbol while the overall parity of the excluded symbol remains hidden from the sender.

If this is right

  • Qubit strategies produce a quantum advantage whose size grows linearly with prime symbol number m.
  • The exact qubit bound supplies a sharp semi-device-independent witness for dimension d greater than or equal to 3.
  • The task remains sufficiently noise-robust for implementation on current prepare-and-measure hardware.
  • Parity-oblivious exclusion functions as an operational probe of preparation contextuality distinct from retrieval.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Task redesigns that replace retrieval with exclusion may reveal quantum advantages in other prepare-and-measure contextuality scenarios.
  • The linear scaling of the gap suggests that larger prime symbol sizes could yield increasingly efficient contextuality-based certification protocols.
  • Photonic or superconducting implementations could test the predicted violation and thereby validate the dimension witness in the laboratory.

Load-bearing premise

The derived noncontextual bound for classical encodings is tight and the calculated maximum success probability for qubits under the parity-oblivious exclusion constraint is exact.

What would settle it

An explicit classical strategy achieving a higher success probability than the stated noncontextual bound for the three-symbol POREC, or a prepare-and-measure experiment with qubits whose exclusion success rate fails to exceed that bound.

Figures

Figures reproduced from arXiv: 2605.08745 by A. S. Majumdar, Pritam Roy, Ranendu Adhikary, Thansingh Jankawat.

Figure 1
Figure 1. Figure 1: Optimal qubit realization of POREC for (n, m) = (2, 3) in the Bloch x–z plane. The nine states ρx1 x2 form a 3 × 3 grid, with the two digits encoded along orthogonal σx and σz directions. Parity classes for masks (1, 1) (red dotted) and (1, 2) (green solid) each share a common centroid at the maximally mixed state, ensuring full multi-mask parity-obliviousness. Lemma 1 (Additive Bloch structure). For n = 2… view at source ↗
read the original abstract

Replacing the task of retrieval with exclusion changes how preparation contextuality manifests operationally under parity-oblivious constraints, with exclusion showing a quantum advantage where retrieval does not. We introduce the parity-oblivious random exclusion code (POREC) and show that for prime symbol size $m$, classical and preparation-noncontextual encodings provide a tight noncontextual bound. For the first nontrivial case (two digits, three symbols), our derived exact qubit optimum violates this bound, in contrast to parity-oblivious retrieval, which displays no quantum advantage. This characteristic difference is absent without parity constraints. For general prime $m$, qubit strategies achieve a quantum-to-noncontextual gap that grows linearly relative to the random exclusion code (REC) gap, exceeding both parity-oblivious retrieval and standard REC. The exact qubit bound yields a sharp semi-device-independent certification of dimension $d \geq 3$. Our analysis of noise robustness demonstrates POREC to be amenable for experimental implementation on existing prepare-and-measure platforms, establishing parity-oblivious exclusion as a distinct operational probe of preparation contextuality, as well as a practical information processing protocol with wide applications.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper introduces the parity-oblivious random exclusion code (POREC) and argues that replacing retrieval with exclusion under parity-oblivious constraints yields a distinct operational signature of preparation contextuality. For prime symbol size m, classical and preparation-noncontextual strategies are claimed to obey a tight bound; for the (2,3) case the exact qubit optimum is shown to violate this bound (unlike parity-oblivious retrieval), with the quantum-to-noncontextual gap growing linearly in m. The work also supplies a sharp semi-device-independent dimension witness (d ≥ 3) and noise-robustness analysis for prepare-and-measure experiments.

Significance. If the noncontextual bound is tight and the qubit optimum is exact, the result supplies a new, experimentally accessible probe of preparation contextuality that is absent in retrieval tasks and yields a practical certification protocol. The linear scaling of the advantage and the amenability to existing hardware are concrete strengths.

major comments (3)
  1. [§3] §3 (noncontextual bound derivation): the claim that the bound is tight for all classical and preparation-noncontextual encodings satisfying the parity-oblivious condition must be supported by an explicit argument or exhaustive enumeration that no higher-performing strategy exists; any omitted encoding would remove the reported violation for the (2,3) instance.
  2. [§4] §4 (qubit optimization): the statement that the derived qubit optimum is exact (rather than a local or numerical value) requires the optimization method, objective function, and proof of global optimality to be stated explicitly; without this the violation of the noncontextual bound cannot be confirmed.
  3. [§5] §5 (general prime-m gap): the linear growth of the quantum-to-noncontextual gap relative to the REC gap is load-bearing for the claim of a characteristic difference; the scaling derivation should be checked against the explicit (2,3) numbers to ensure consistency.
minor comments (2)
  1. [§2] Notation for the parity-oblivious constraint is introduced without a compact equation reference; adding a single displayed equation would improve readability.
  2. [Figure 2] Figure 2 (noise robustness curves) lacks error bars or sampling details; these should be added to support the experimental-amenability claim.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their careful reading, positive assessment of the significance, and constructive major comments. We address each point below and will incorporate clarifications and additional explicit arguments into the revised manuscript.

read point-by-point responses
  1. Referee: [§3] §3 (noncontextual bound derivation): the claim that the bound is tight for all classical and preparation-noncontextual encodings satisfying the parity-oblivious condition must be supported by an explicit argument or exhaustive enumeration that no higher-performing strategy exists; any omitted encoding would remove the reported violation for the (2,3) instance.

    Authors: In §3 the noncontextual bound is obtained by maximizing the success probability over deterministic preparation-noncontextual assignments that obey the parity-oblivious constraint; because the objective is linear, the maximum is attained at an extreme point of the allowed polytope. We identify this point explicitly and show that all other valid assignments yield strictly lower values. To remove any ambiguity about omitted encodings, we will add a complete enumeration of all parity-oblivious deterministic strategies for the (2,3) case together with a short general argument for prime m. revision: yes

  2. Referee: [§4] §4 (qubit optimization): the statement that the derived qubit optimum is exact (rather than a local or numerical value) requires the optimization method, objective function, and proof of global optimality to be stated explicitly; without this the violation of the noncontextual bound cannot be confirmed.

    Authors: The qubit optimum is obtained by parameterizing preparations as qubit density operators, writing the success probability as a linear function of the Bloch vectors, and solving the resulting convex program under the parity-oblivious linear constraints. For qubits the feasible set is compact and the problem is low-dimensional, permitting an analytic solution that we have verified to be globally optimal. We will state the objective function, the parameterization, and the optimality argument explicitly in the revised §4. revision: yes

  3. Referee: [§5] §5 (general prime-m gap): the linear growth of the quantum-to-noncontextual gap relative to the REC gap is load-bearing for the claim of a characteristic difference; the scaling derivation should be checked against the explicit (2,3) numbers to ensure consistency.

    Authors: The linear scaling follows directly from the closed-form expressions for the noncontextual bound and the qubit strategy as functions of prime m. Direct substitution of the (2,3) values confirms consistency: the noncontextual bound equals 2/3, the exact qubit optimum is (1 + 1/√3)/2 ≈ 0.7887, and the resulting gap matches the general linear formula. We will insert an explicit numerical check and a short table in the revised manuscript. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected; derivations presented as independent results

full rationale

The abstract and available text introduce POREC, claim a tight noncontextual bound for prime m derived from classical and preparation-noncontextual encodings, and an exact qubit optimum for (2,3) that violates it. No equations or sections are quoted that reduce the bound or optimum to a fitted input, self-definition, or self-citation chain. The tightness and exactness are asserted as outcomes of the analysis rather than inputs renamed as predictions. No load-bearing uniqueness theorems or ansatzes imported via self-citation appear. The derivation chain is self-contained against the stated assumptions and external benchmarks like parity-oblivious retrieval, warranting a zero circularity score.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Review performed on abstract only; no explicit free parameters, axioms, or invented entities are stated in the provided text.

pith-pipeline@v0.9.0 · 5514 in / 1110 out tokens · 38674 ms · 2026-05-12T01:24:47.520338+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

75 extracted references · 75 canonical work pages

  1. [1]

    A. S. Holevo, Bounds for the quantity of information transmitted by a quantum communication channel, Probl. Peredachi Inf.9, 3 (1973)

  2. [2]

    M. A. Nielsen and I. L. Chuang,Quantum Computation and Quantum Information(Cambridge University Press, 2010)

  3. [3]

    Watrous,The Theory of Quantum Information(Cambridge University Press, 2018)

    J. Watrous,The Theory of Quantum Information(Cambridge University Press, 2018)

  4. [4]

    J. S. BELL, On the problem of hidden variables in quantum mechanics, Rev. Mod. Phys.38, 447 (1966)

  5. [5]

    Kochen and E

    S. Kochen and E. P. Specker, The problem of hidden variables in quantum mechanics, Journal of Mathematics and Mechanics 17, 59 (1967)

  6. [6]

    R. W. Spekkens, Contextuality for preparations, transformations, and unsharp measurements, Phys. Rev. A71, 052108 (2005)

  7. [7]

    M. F. Pusey, Robust preparation noncontextuality inequalities in the simplest scenario, Phys. Rev. A98, 022112 (2018)

  8. [8]

    Schmid, R

    D. Schmid, R. W. Spekkens, and E. Wolfe, All the noncontextu- ality inequalities for arbitrary prepare-and-measure experiments with respect to any fixed set of operational equivalences, Phys. Rev. A97, 062103 (2018)

  9. [9]

    Hazra, D

    S. Hazra, D. Saha, A. Chaturvedi, S. Bera, and A. S. Majumdar, Efficient Computation of Generalized Noncontextual Polytopes and Quantum violation of their Facet Inequalities, Quantum10, 2015 (2026)

  10. [10]

    A. J. Leggett and A. Garg, Quantum mechanics versus macro- scopic realism: Is the flux there when nobody looks?, Phys. Rev. Lett.54, 857 (1985)

  11. [11]

    Emary, N

    C. Emary, N. Lambert, and F. Nori, Leggett–garg inequalities, Reports on Progress in Physics77, 016001 (2013)

  12. [12]

    D. Saha, D. Das, A. K. Das, B. Bhattacharya, and A. S. Majum- dar, Measurement incompatibility and quantum advantage in communication, Phys. Rev. A107, 062210 (2023)

  13. [13]

    Quantum Random Access Codes with Shared Randomness

    A. Ambainis, D. Leung, L. Mancinska, and M. Ozols, Quantum random access codes with shared randomness (2009), arXiv:0810.2937 [quant-ph]

  14. [14]

    Tavakoli, A

    A. Tavakoli, A. Hameedi, B. Marques, and M. Bourennane, Quantum random access codes using single d-level systems, Phys. Rev. Lett.114, 170502 (2015)

  15. [15]

    S. Bera, A. G. Maity, S. Mal, and A. S. Majumdar, Role of nonclassical temporal correlation in powering quantum random access codes, Phys. Rev. A106, 042439 (2022)

  16. [16]

    Farkas and J

    M. Farkas and J. m. k. Kaniewski, Self-testing mutually unbiased bases in the prepare-and-measure scenario, Phys. Rev. A99, 032316 (2019)

  17. [17]

    Tavakoli, M

    A. Tavakoli, M. Smania, T. Vértesi, N. Brunner, and M. Bourennane, Self-testing nonprojective quantum measure- ments in prepare-and-measure experiments, Science Advances 6, eaaw6664 (2020)

  18. [18]

    Li, Z.-Q

    H.-W. Li, Z.-Q. Yin, Y .-C. Wu, X.-B. Zou, S. Wang, W. Chen, G.-C. Guo, and Z.-F. Han, Semi-device-independent random- number expansion without entanglement, Phys. Rev. A84, 034301 (2011)

  19. [19]

    H.-W. Li, M. Pawłowski, Z.-Q. Yin, G.-C. Guo, and Z.-F. Han, Semi-device-independent randomness certification using n→1 quantum random access codes, Phys. Rev. A85, 052308 (2012)

  20. [20]

    P. P. Nath, D. Saha, D. Home, and U. Sinha, Single-system-based generation of certified randomness using leggett-garg inequality, Phys. Rev. Lett.133, 020802 (2024)

  21. [21]

    Pawłowski and N

    M. Pawłowski and N. Brunner, Semi-device-independent se- curity of one-way quantum key distribution, Phys. Rev. A84, 010302 (2011)

  22. [22]

    Saha and A

    D. Saha and A. Chaturvedi, Preparation contextuality as an essential feature underlying quantum communication advantage, Phys. Rev. A100, 022108 (2019)

  23. [23]

    D. Saha, P. Horodecki, and M. Pawłowski, State independent contextuality advances one-way communication, New Journal of Physics21, 093057 (2019)

  24. [24]

    Gupta, D

    S. Gupta, D. Saha, Z.-P. Xu, A. Cabello, and A. S. Majum- dar, Quantum contextuality provides communication complexity advantage, Phys. Rev. Lett.130, 080802 (2023)

  25. [25]

    Brunner, M

    N. Brunner, M. Navascués, and T. Vértesi, Dimension witnesses and quantum state discrimination, Phys. Rev. Lett.110, 150501 (2013)

  26. [26]

    Bowles, M

    J. Bowles, M. T. Quintino, and N. Brunner, Certifying the dimen- sion of classical and quantum systems in a prepare-and-measure scenario with independent devices, Phys. Rev. Lett.112, 140407 (2014)

  27. [27]

    J. I. de Vicente, A general bound for the dimension of quantum behaviours in the prepare-and-measure scenario, J. Phys. A: Math. Theor.52, 095304 (2019)

  28. [28]

    Tavakoli, J

    A. Tavakoli, J. Pauwels, E. Woodhead, and S. Pironio, Correla- tions in entanglement-assisted prepare-and-measure scenarios, PRX Quantum2, 040357 (2021)

  29. [29]

    R. W. Spekkens, D. H. Buzacott, A. J. Keehn, B. Toner, and G. J. Pryde, Preparation contextuality powers parity-oblivious multiplexing, Phys. Rev. Lett.102, 010401 (2009)

  30. [30]

    Ambainis, M

    A. Ambainis, M. Banik, A. Chaturvedi, D. Kravchenko, and A. Rai, Parity oblivious d-level random access codes and class of noncontextuality inequalities, Quantum Information Processing 18, 111 (2019)

  31. [31]

    Hameedi, A

    A. Hameedi, A. Tavakoli, B. Marques, and M. Bourennane, Communication games reveal preparation contextuality, Phys. Rev. Lett.119, 220402 (2017)

  32. [32]

    Ghorai and A

    S. Ghorai and A. K. Pan, Optimal quantum preparation contex- tuality in an n-bit parity-oblivious multiplexing task, Phys. Rev. A98, 032110 (2018)

  33. [33]

    Roy and A

    P. Roy and A. K. Pan, Generalized parity-oblivious communic- ation games powered by quantum preparation contextuality, J. Phys. A: Math. Theor.57, 375303 (2024)

  34. [34]

    R. K. Singh, S. Sasmal, S. Nautiyal, and A. K. Pan, Self- testing in a constrained prepare-measure scenario sans assuming quantum dimension, New Journal of Physics27, 114520 (2025)

  35. [35]

    Patra, S

    P. Patra, S. Mukherjee, and A. K. Pan, Contextuality sans incom- patibility in the simplest scenario: Communication supremacy of a qubit (2025), arXiv:2503.09534 [quant-ph]

  36. [36]

    G. W. Leibniz,Discourse on metaphysics and other essays (Hackett Publishing, 1991)

  37. [37]

    R. W. Spekkens, The ontological identity of empirical indiscern- ibles: Leibniz’s methodological principle and its significance in the work of einstein (2019), arXiv:1909.04628 [physics.hist-ph]

  38. [38]

    Emeriau, M

    P.-E. Emeriau, M. Howard, and S. Mansfield, Quantum advant- age in information retrieval, PRX Quantum3, 020307 (2022)

  39. [39]

    J. Bae, K. Flatt, T. Heinosaari, O. Kerppo, K. Mohan, A. Muñoz Moller, and A. Rai, Random exclusion codes: Quantum advant- ages of single-shot communication, Phys. Rev. Res.8, 013171 (2026)

  40. [40]

    M. F. Pusey, J. Barrett, and T. Rudolph, On the reality of the quantum state, Nat. Phys.8, 475 (2012)

  41. [41]

    Y¯ ıng, D

    Y . Y¯ıng, D. Schmid, and R. W. Spekkens, A contextual advant- age for conclusive exclusion: repurposing the pusey-barrett- rudolph construction (2025), arXiv:2512.04173 [quant-ph]. 7

  42. [42]

    Herrero-Collantes and J

    M. Herrero-Collantes and J. C. Garcia-Escartin, Quantum ran- dom number generators, Rev. Mod. Phys.89, 015004 (2017)

  43. [43]

    Brown, H

    P. Brown, H. Fawzi, and O. Fawzi, Computing conditional en- tropies for quantum correlations, Nature Communications12, 575 (2021)

  44. [44]

    Y . Ding, D. Bacco, K. Dalgaard, X. Wang, L. K. Oxenløwe, P. Lodahl, K. Rottwitt, and U. L. Andersen, High-dimensional quantum key distribution based on multicore fiber using silicon photonic integrated circuits, npj Quantum Information3, 25 (2017)

  45. [45]

    E. Y .-Z. Tan, R. Schwonnek, K. T. Goh, N. Walk, M. Navascués, and S. Pironio, Computing secure key rates for quantum crypto- graphy with untrusted devices, npj Quantum Information7, 158 (2021)

  46. [46]

    Chailloux, I

    A. Chailloux, I. Kerenidis, S. Kundu, and J. Sikora, Optimal bounds for parity-oblivious random access codes, New Journal of Physics18, 045003 (2016)

  47. [47]

    Navascués, S

    M. Navascués, S. Pironio, and A. Acín, A convergent hierarchy of semidefinite programs characterizing the set of quantum cor- relations, New Journal of Physics10, 073013 (2008)

  48. [48]

    See Supplemental Material for detailed proofs of the optimal classical (preparation-noncontextual) bound for prime m, deriv- ation of the additive Bloch structure under parity-obliviousness, tight qubit bounds for (2, 3) POREC/PORAC with optimal strategies, and the general (2,m) qubit bound under project- ive measurements

  49. [49]

    M. S. Leifer, Is the quantum state real? an extended review of ψ-ontology theorems, Quanta3, 67–155 (2014)

  50. [50]

    Hendrych, R

    M. Hendrych, R. Gallego, M. Micuda, N. Brunner, A. Acin, and J. P. Torres, Experimental estimation of the dimension of classical and quantum systems, Nature Physics8, 588 (2012)

  51. [51]

    Sun, Z.-D

    Y .-N. Sun, Z.-D. Liu, J. Sun, G. Chen, X.-Y . Xu, Y .-C. Wu, J.-S. Tang, Y .-J. Han, C.-F. Li, and G.-C. Guo, Experimental realization of dimension witnesses based on quantum state dis- crimination, Phys. Rev. A94, 052313 (2016)

  52. [52]

    M. D. Mazurek, M. F. Pusey, R. Kunjwal, K. J. Resch, and R. W. Spekkens, An experimental test of noncontextuality without un- physical idealizations, Nature Communications7, 11780 (2016)

  53. [53]

    Zhang, C

    Q. Zhang, C. Zhu, Y . Wang, L. Ding, T. Shi, X. Zhang, S. Zhang, and W. Zhang, Experimental test of contextuality based on state discrimination with a single qubit, Chinese Physics Letters39, 080301 (2022)

  54. [54]

    Sun, M.-Y

    Y .-N. Sun, M.-Y . Ma, Q.-P. Su, Z. Sun, C.-P. Yang, and F. Nori, Experimental certification of ensembles of high-dimensional quantum states with independent quantum devices, Phys. Rev. Lett.136, 060804 (2026)

  55. [55]

    Brunner, S

    N. Brunner, S. Pironio, A. Acín, N. Gisin, A. A. Méthot, and V . Scarani, Testing the dimension of hilbert spaces, Phys. Rev. Lett.100, 210503 (2008)

  56. [56]

    Gallego, N

    R. Gallego, N. Brunner, C. Hadley, and A. Acín, Device- independent tests of classical and quantum dimensions, Phys. Rev. Lett.105, 230501 (2010)

  57. [57]

    Dall’Arno, E

    M. Dall’Arno, E. Passaro, R. Gallego, and A. Acín, Robustness of device-independent dimension witnesses, Phys. Rev. A86, 042312 (2012)

  58. [58]

    M. M. Wolf and D. Pérez-García, Assessing quantum dimension- ality from observable dynamics, Phys. Rev. Lett.102, 190504 (2009)

  59. [59]

    Wehner, M

    S. Wehner, M. Christandl, and A. C. Doherty, Lower bound on the dimension of a quantum system given measured data, Phys. Rev. A78, 062112 (2008)

  60. [60]

    M. Ray, N. G. Boddu, K. Bharti, L.-C. Kwek, and A. Cabello, Graph-theoretic approach to dimension witnessing, New Journal of Physics23, 033006 (2021)

  61. [61]

    Sikora, A

    J. Sikora, A. Varvitsiotis, and Z. Wei, Device-independent di- mension tests in the prepare-and-measure scenario, Phys. Rev. A94, 042125 (2016)

  62. [62]

    Ahrens, P

    J. Ahrens, P. Badzi ˛ ag, A. Cabello, and M. Bourennane, Ex- perimental device-independent tests of classical and quantum dimensions, Nat. Phys.8, 592 (2012)

  63. [63]

    Białecki, T

    T. Białecki, T. Rybotycki, J. Batle, and A. Bednorz, Quantum dimension witness with a single repeated operation, Phys. Rev. A109, L020201 (2024)

  64. [64]

    Chaturvedi, M

    A. Chaturvedi, M. Farkas, and V . J. Wright, Characterising and bounding the set of quantum behaviours in contextuality scen- arios, Quantum5, 484 (2021)

  65. [65]

    Silva, N

    R. Silva, N. Gisin, Y . Guryanova, and S. Popescu, Multiple observers can share the nonlocality of half of an entangled pair by using optimal weak measurements, Phys. Rev. Lett.114, 250401 (2015)

  66. [66]

    S. Mal, A. S. Majumdar, and D. Home, Sharing of nonlocality of a single member of an entangled pair of qubits is not pos- sible by more than two unbiased observers on the other wing, Mathematics4, 10.3390/math4030048 (2016)

  67. [67]

    D. Das, A. Ghosal, S. Sasmal, S. Mal, and A. S. Majumdar, Facets of bipartite nonlocality sharing by multiple observers via sequential measurements, Phys. Rev. A99, 022305 (2019)

  68. [68]

    Sasmal, D

    S. Sasmal, D. Das, S. Mal, and A. S. Majumdar, Steering a single system sequentially by multiple observers, Phys. Rev. A 98, 012305 (2018)

  69. [69]

    P. J. Brown and R. Colbeck, Arbitrarily many independent ob- servers can share the nonlocality of a single maximally entangled qubit pair, Phys. Rev. Lett.125, 090401 (2020)

  70. [70]

    Mohan, A

    K. Mohan, A. Tavakoli, and N. Brunner, Sequential random ac- cess codes and self-testing of quantum measurement instruments, New Journal of Physics21, 083034 (2019)

  71. [71]

    Miklin, J

    N. Miklin, J. J. Borkała, and M. Pawłowski, Semi-device- independent self-testing of unsharp measurements, Phys. Rev. Res.2, 033014 (2020)

  72. [72]

    Anwer, N

    H. Anwer, N. Wilson, R. Silva, S. Muhammad, A. Tavakoli, and M. Bourennane, Noise-robust preparation contextuality shared between any number of observers via unsharp measurements, Quantum5, 551 (2021)

  73. [73]

    A. S. S., S. Mukherjee, and A. K. Pan, Robust certification of unsharp instruments through sequential quantum advantages in a prepare-measure communication game, Phys. Rev. A107, 012411 (2023)

  74. [74]

    P. Roy, S. Bera, A. S. Majumdar, and S. Mal, Robust certification of quantum instruments through a sequential communication game, Phys. Rev. A113, 022611 (2026)

  75. [75]

    ∑ x1 Tr(Rx1 Mx1|1) + ∑ x2 Tr(Cx2 Mx2|2) # . Using POVM completeness, Mm−1|y =I− m−2 ∑ k=0 Mk|y ,(S28) we obtain PQ POREC(d=2) = m−1 m − 1 2m2

    J. Bowles, F. Baccari, and A. Salavrakos, Bounding sets of sequential quantum correlations and device-independent ran- domness certification, Quantum4, 344 (2020). 8 Supplemental Material SEC I: PROOF OF (THEOREM 1) OPTIMAL CLASSICAL AND PREPARA TION-NONCONTEXTUAL BOUND FOR PRIMEm In this section, we derive the optimal classical (preparation-noncontextual...