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This paper proves that intrinsically quantum effects of weakly coupled waves — axion dark matter and gravitational radiation — are suppressed by an extra power of the tiny conversion efficiency η, making them undetectable by current or fore

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2026-08-01 09:40 UTC pith:FY7ZSYUO

load-bearing objection Solid extension of the PRL: a general η-suppression theorem for single-cavity observables, entanglement, and decoherence; the categorical claims outrun the proofs only where the companion paper is still unpublished. the 3 major comments →

arxiv 2607.27313 v1 pith:FY7ZSYUO submitted 2026-07-29 hep-ph gr-qchep-exhep-thquant-ph

Suppressed Quantum Effects of Weakly Coupled Waves

Yunjia Bao , Dhong Yeon Cheong , Nicholas L. Rodd , Joey Takach , Lian-Tao Wang , Kevin Zhou This is my paper
classification hep-ph gr-qchep-exhep-thquant-ph
keywords axion dark mattergravitational wavesnonclassicalityP-functioneffective modescavity haloscopeweak coupling suppressionquantum central limit theorem
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

This paper aims to settle a question raised by precision experiments: could a detector of axion dark matter or gravitational waves ever show that the detected field is quantized? It argues no, for two independent reasons. First, a detector couples not to a fundamental field mode but to a coarse-grained "effective mode"; when many independent modes contribute, a quantum central-limit theorem makes that mode a thermal Gaussian state, which is classically simulable regardless of the underlying state. Second, even granting a maximally nonclassical effective mode, every intrinsically quantum signature is suppressed by an extra power of the tiny conversion efficiency η — the fraction of wave quanta turned into detector quanta — with no compensation from the enormous mode occupancy. The paper proves this suppression generally for number, quadrature, entanglement, and decoherence observables, and concludes that detecting quantization would require integration times or quantum resources scaling as 1/η that are far beyond current experiments.

Core claim

The central claim, stated on the paper's own terms, is that the evolution of a weakly coupled wave onto a detector is a linear beam-splitter mixing with efficiency η = sin²(gt) ≪ 1, so the detector's final P-function is a convolution of the initial detector state with the wave's P-function compressed by √η. This compression forces any negativity in the wave's quasiprobability distribution into rapid sign oscillations that cancel against smooth measurement functions; the general calculation shows the probability of any single-detector outcome differs from that of a Gaussian-smeared, classical proxy state by (η/4)∫P_fc ∇²f_O + O(η²). As a result, nonclassicality measures obey Q_c = ηQ_a for nu

What carries the argument

The key object is the P-function — a quasiprobability distribution that is nonnegative exactly for classically describable states — together with the beam-splitter Hamiltonian ig(c†a − ca†). For small η the final detector P-function becomes P_c(γ,t) = ∫dα P_a(α/√η)/η P_c(γ−α): nonclassical negativity is transferred to the detector but squeezed into a √η-wide structure. The proof's load-bearing identity is the expansion of a narrow Gaussian convolution of the measurement function f_O, giving p_cl − p = (η/4)∫P_fc ∇²f_O + O(η²), which bounds the visibility of any nonclassical effect. A second mechanism, the effective-mode construction, defines a single detector-coupled wave mode by form-factor

Load-bearing premise

The load-bearing premise — flagged by the paper in Sec. 6.1 — is that any realistic detection channel reduces to a single weakly coupled linear mixing with efficiency η, with continuous measurement deferred to a companion work and parametric couplings (dilaton, quadratic scalars, gravitational-wave squeezing) left as an expectation rather than a proof; if a real channel violates this reduction, the η-suppression power counting could change.

What would settle it

Concrete test: prepare (or discover) an axion effective mode in a Fock state, perform ~1/η² independent projective photon-number measurements on the cavity, and look for the predicted negative Q_c ≈ −η, i.e. a two-photon probability p2 = ½⟨n_c⟩(⟨n_c⟩ − η) below the coherent-state value. Observing a deficit at this level, or any O(1) nonclassical deviation that the Gaussian-smeared classical proxy cannot reproduce, would refute the claimed universal suppression. A complementary check is continuous-measurement statistics in an operating haloscope: if they deviate from classical-field predictions

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • If the paper is correct, no axion haloscope or gravitational-wave observatory — current or projected — can establish that the target field is quantized; graviton number or Fock-state signatures are suppressed below detectability.
  • Discovering the wave and distinguishing classical models of it (e.g. coherent vs thermal-Gaussian statistics) can remain feasible, but that distinction is not a test of quantization.
  • Any attempt to see negative Q, quadrature squeezing, or cavity-mode entanglement from the wave requires either integration times tint ~ tm/η² (≈10^17 yr for typical haloscope parameters) or initial cavity states with variance ~η, which are beyond present technology.
  • For virialized axion dark matter, the quantum central limit theorem predicts that detectors see a classical Gaussian random field with occupancy Neff, regardless of the quantum state of individual fundamental modes.
  • The suppression applies uniformly to number, quadrature, entanglement, and decoherence observables, so no clever choice of observable can evade it.

Where Pith is reading between the lines

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

  • Editorial extension: if the stated companion analysis confirms the same scaling for continuous measurement, the conclusion closes the loophole that continuous-mode detectors might behave differently from the projective model treated here.
  • Editorial extension: the mechanism is essentially "nonclassicality is fragile under weak transduction"; it should hold for any detector whose interaction is number-conserving linear mixing, including LC-circuit, heterodyne, and optomechanical detectors, not just cavities.
  • Editorial extension: for parametric couplings (dilaton dark matter, quadratically coupled scalars, gravitational-wave squeezing) the paper only expects suppression; computing nonclassicality measures for those interactions would be a direct test of whether the power counting survives beyond linear mixing.
  • Editorial extension: a practical programmatic consequence of the argument is that quantum-gravity tests should target gravitationally mediated entanglement between masses rather than attempting to observe gravitons in wave detectors.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. The paper studies whether weakly coupled wave fields (axion dark matter, gravitational waves) can reveal intrinsically quantum effects in realistic detectors. Working from a linear-mixing toy Hamiltonian H=ig(c†a−ca†) and an effective-mode description of a cavity haloscope, the authors derive the final cavity P-function as a scaled convolution of the axion and cavity P-functions. They then prove that nonclassicality measures in the cavity are suppressed by the conversion efficiency η: Mandel Q_c=ηQ_a, squeezing S_c=ηS_a, and two-mode entanglement E_c=ηE_a. A general argument in Sec. 4.3 bounds the difference between any single-cavity measurement outcome and that of a classical, Q-smeared proxy by O(η), and Sec. 5 derives a similar suppression for purity loss. The authors conclude that no current or foreseeable detector can establish the quantization of axions or gravitational waves. The formal derivations are largely standard and key equations check out, but the manuscript's broadest claims extend beyond the proven projective-measurement, linear-mixing setting.

Significance. If the result holds in full generality, it substantially sharpens the debate on detecting quantum effects of weakly coupled fields: it gives a parameter-free scaling argument that nonclassical signatures are suppressed by η without compensation by the large occupancy N_eff. The paper has clear strengths: the exact P-function treatment of the beam-splitter-like conversion map, the careful CLT argument for coarse-grained effective modes, the explicit derivation of η suppression for number, quadrature, and entanglement witnesses, and a critical review of prior claims. There are no fitted parameters; η, N_eff, and Ω_010 are derived from physical inputs. The limitations are scope limitations rather than internal inconsistencies in the core derivation.

major comments (3)
  1. [Sec. 1 (p.5) and Sec. 6.1 (p.38)] The headline claim—that no current or foreseeable detector can establish quantization—is applied to HAYSTAC and LIGO, but the theorem is proven only for a repeated projective-measurement protocol. Section 6.1 explicitly defers continuous measurement to an unpublished companion [39] and offers only a heuristic equivalence at rate κ. Continuous measurement has different backaction and statistics; it is not covered by Eq. (4.25) or the trace-distance argument of Sec. 4.3. As written, the manuscript proves suppression for discrete measurements and conjectures it for the experimental protocols of HAYSTAC/LIGO. This is a load-bearing scope gap: if the companion calculation does not reproduce an O(η) closeness of the photocurrent distribution, the central conclusion is not established. The authors should either include the continuous-measurement calculation or explicitly restrict the abstract a
  2. [Sec. 6.1, 'Parametric Interactions'] The abstract and concluding paragraphs claim applicability to 'many ultralight dark matter searches' and rule out proposals for quantum gravity, but parametric couplings such as dilaton (a+a†)(c+c†)^2 and quadratic scalar (a+a†)^2(c+c†)^2 do not reduce to the linear-mixing map Eq. (2.10) used in the proof. The text only states 'we expect they will also be suppressed' and gives no calculation or scaling argument specific to these Hamiltonians. Since parametric drives can themselves create nonclassical detector states, this is not a trivial corollary. The scope should be narrowed to linear-mixing detectors, or the parametric case must be analyzed.
  3. [Sec. 4.3 and Sec. 6.2 (p.41)] The general suppression argument assumes that measurements can be repeated independently and that the effective-mode state is not modified by backreaction. The paper acknowledges in Sec. 6.2 that for states such as |α⟩+|−α⟩, a single phase-sensitive measurement can decohere the axion state, so the 'independent repeated measurements' assumption is not valid for exactly the states that are most nonclassical. This does not invalidate the suppression bound, but it means the quoted integration times such as Eq. (4.11), t_int∼t_m/η², should be presented as an optimistic lower bound under the independence assumption, not as the actual requirement in all scenarios. The conclusion that detection is impractical is likely robust, but the stated power counting is not the full story.
minor comments (4)
  1. [Eq. (4.29)] The Taylor expansion for f_O is justified for smooth measurement functions, but Fock projectors with large n can have large derivatives. The trace-distance bound partially covers this, but the sentence 'one needs at least ∼1/η measurements' should be reconciled with the 1/η² estimates of Secs. 4.1–4.2; as stated it is a weak lower bound.
  2. [Sec. 3.1, Eq. (3.11)] The non-orthogonality of effective modes [a_ℓ,a_m†]≠0 is discussed, but the multi-cavity entanglement result in Eq. (4.35) assumes widely separated cavities. This assumption is stated, but it would be useful to note explicitly that in a single cavity the effective-mode commutator prevents a direct factorized treatment.
  3. [Fig. 4] The vertical axis is labeled γ_eff while the text uses γ for purity; please unify notation for readability.
  4. [References] The companion reference [39] is cited as 'To appear' but is load-bearing for the continuous-measurement claim. If it is not yet public, the manuscript should either include the relevant calculation in an appendix or clearly mark the conclusion as conditional.

Circularity Check

0 steps flagged

No significant circularity: the suppression theorems are derived in-text from the linear-mixing P-function map; self-citations are contextual, not load-bearing.

full rationale

The central results—η-suppression of Mandel Q, squeezing, entanglement, decoherence, and the universal classical-proxy theorem—are derived within the paper from the cavity P-function evolution (Eqs. 2.8–2.10) and from the Gaussian-smeared Q-function comparison (Eqs. 4.25–4.30). The parameters η, Neff, and Ω010 are computed from physical inputs (Eqs. 3.16, 3.19, 4.2), with no fitted parameter renamed as a prediction. The paper cites the same authors' PRL [33] and Ref. [24], but the load-bearing derivations are reproduced here (e.g., Q_c = ηQ_a in Eq. 4.5, S_c = ηS_a in Eq. 4.21); the self-citations are contextual and do not carry the argument. The paper does explicitly limit the proven regime to repeated projective measurements and defers continuous measurement—the mode relevant to HAYSTAC and LIGO—to an unpublished companion [39] (Sec. 1 and Sec. 6.1), with parametric couplings covered only by the heuristic expectation that they 'will also be suppressed by an extra power of the low efficiency η' (Sec. 6.1). These are scope limitations, not circular reductions: they affect the breadth of the claim, not the internal validity of the derivation within the stated model. No step in the derivation is equivalent by construction to its own input, so the circularity score is minimal.

Axiom & Free-Parameter Ledger

0 free parameters · 6 axioms · 1 invented entities

No numbers are fitted to data: η (Eq. 4.2), Neff (Eq. 3.16), and Ω010 (Eq. 3.19) are computed from physical inputs (coupling, field, quality factor, mass, geometry). The central claims rest on standard quantum-optics mathematics (P representation, CLT, beam-splitter evolution) plus three domain assumptions that the paper itself identifies and discusses: mode-factorization/stationarity for the CLT result, single-effective-mode reduction, and projective measurement with no back-reaction. The parametric-interaction extrapolation (Sec. 6.1) is flagged as an expectation, not an axiom.

axioms (6)
  • standard math Glauber-Sudarshan P representation applies to all states, with negative/singular P signifying nonclassicality; optical equivalence theorem for normally ordered observables.
    Used throughout Secs. 2-4; definitions and singularity handling in Sec. 2 and App. C.1-C.2.
  • standard math Rotating wave approximation: off-resonant ac and a†c† terms dropped; corrections O(g/ω) are Qc-suppressed.
    Sec. 2, Eqs. (2.2) and footnote 3.
  • domain assumption The DM field state factorizes over fundamental modes, P_a(α)=∏_k P_k(α_k), with many comparable-weight modes so the quantum CLT applies.
    Sec. 3.2, Eqs. (3.25)-(3.28); evasions (correlations, N=1 condensates, squeezed-axis alignment) discussed in 'Evading the Quantum CLT', p.19.
  • domain assumption The effective DM mode is stationary (⟨ak⟩=⟨ak²⟩=0), so the CLT result is a thermal Gaussian rather than a squeezed state.
    Sec. 3.2 p.17; justified by phase spreading TΔω≫1 for propagated axions, with monochromatic late-time sources as the exception.
  • domain assumption The detector couples to a single effective mode; non-orthogonality [aℓ,a†m]≠0 is negligible for single-mode readout.
    Sec. 3.1, Eq. (3.11) and p.13; the commutator failure is computed and argued irrelevant for haloscope readout.
  • domain assumption Repeated projective measurements with negligible back-reaction on the wave state; cavity dissipation neglected (t≲Qc/ω).
    Sec. 2 p.6; Sec. 4 intro p.20; acknowledged as optimistic in Sec. 6, and measurement-induced decoherence of |α⟩+|−α⟩ states is conceded in Sec. 6.2.
invented entities (1)
  • Effective axion mode aℓ (Eq. 3.9) independent evidence
    purpose: Coarse-grained linear combination of fundamental axion plane-wave modes that the cavity actually couples to; maps the continuum haloscope problem onto the solvable toy model.
    A derived, normalized operator (Eqs. 3.9-3.10) whose occupancy Neff~10^19 (Eq. 3.16) and form factors make falsifiable statements about haloscope signal rates. It is a bookkeeping device inherited from Ref. [24], not a speculative new physical entity.

pith-pipeline@v1.3.0-daily-deepseek · 51325 in / 22718 out tokens · 185959 ms · 2026-08-01T09:40:58.151500+00:00 · methodology

0 comments
read the original abstract

Precision experiments increasingly target weakly coupled waves, including axion dark matter and gravitational radiation. Such waves are commonly described as classical fields, yet they could exist in quantum states with no classical counterpart. We exhibit two severe obstructions to detecting nonclassical effects, both independent of the mode occupancy. First, realistic detectors cannot resolve the fundamental modes of a field; instead they couple to coarse-grained "effective" modes, which often washes out nonclassical effects. Second, all nonclassical effects are suppressed by extra powers of the weak coupling, making them much harder to detect than the waves themselves. We prove this in general, and explicitly show how the suppression arises for quadrature and number statistics, entanglement, and decoherence. The suppression can in principle be overcome given suitable quantum resources, such as highly squeezed detector states, but the required parameters are far beyond current experimental capabilities. We use the axion cavity haloscope as an explicit example, although our conclusions apply to many ultralight dark matter searches, and rule out proposals to establish the quantization of gravity from observations of gravitational waves.

discussion (0)

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Reference graph

Works this paper leans on

168 extracted references · 113 linked inside Pith

  1. [1]

    Advanced LIGO,

    LIGO ScientificCollaboration, J. Aasiet al., “Advanced LIGO,”Class. Quant. Grav.32(2015) 074001,arXiv:1411.4547 [gr-qc]. [2]LIGO Scientific, VirgoCollaboration, B. P. Abbottet al., “Observation of Gravitational Waves from a Binary Black Hole Merger,”Phys. Rev. Lett.116no. 6, (2016) 061102, arXiv:1602.03837 [gr-qc]. [3]ADMXCollaboration, S. J. Asztaloset a...

    Pith/arXiv arXiv 2015

  2. [6]

    A Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment,

    ADMXCollaboration, N. Duet al., “A Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment,”Phys. Rev. Lett.120no. 15, (2018) 151301,arXiv:1804.05750 [hep-ex]. [7]ADMXCollaboration, T. Braineet al., “Extended Search for the Invisible Axion with the Axion Dark Matter Experiment,”Phys. Rev. Lett.124no. 10, (2020) 101303, arXiv:1910.0863...

    Pith/arXiv arXiv 2018

  3. [9]

    Quantum frontiers in high energy physics,

    Y. Fang, C. Gao, Y.-Y. Li, J. Shu, Y. Wu, H. Xing, B. Xu, L. Xu, and C. Zhou, “Quantum frontiers in high energy physics,”Sci. China Phys. Mech. Astron.68no. 6, (2025) 260301, arXiv:2411.11294 [hep-ph]. [10]LIGO ScientificCollaboration, J. Aasiet al., “Enhancing the sensitivity of the LIGO gravitational wave detector by using squeezed states of light,”Natu...

    Pith/arXiv arXiv 2025

  4. [12]

    Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit,

    W. Jiaet al., “Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit,”Science385no. 6715, (2024) 1318,arXiv:2404.14569 [gr-qc]

    Pith/arXiv arXiv 2024

  5. [13]

    A Cosmological Bound on the Invisible Axion,

    L. F. Abbott and P. Sikivie, “A Cosmological Bound on the Invisible Axion,”Phys. Lett. B120 (1983) 133–136

    1983

  6. [14]

    Cosmology of the Invisible Axion,

    J. Preskill, M. B. Wise, and F. Wilczek, “Cosmology of the Invisible Axion,”Phys. Lett. B120 (1983) 127–132

    1983

  7. [15]

    The Low-Energy Frontier of Particle Physics,

    J. Jaeckel and A. Ringwald, “The Low-Energy Frontier of Particle Physics,”Ann. Rev. Nucl. Part. Sci.60(2010) 405–437,arXiv:1002.0329 [hep-ph]

    Pith/arXiv arXiv 2010

  8. [16]

    Axion Cosmology,

    D. J. E. Marsh, “Axion Cosmology,”Phys. Rept.643(2016) 1–79,arXiv:1510.07633 [astro-ph.CO]

    Pith/arXiv arXiv 2016

  9. [17]

    New experimental approaches in the search for axion-like particles,

    I. G. Irastorza and J. Redondo, “New experimental approaches in the search for axion-like particles,”Prog. Part. Nucl. Phys.102(2018) 89–159,arXiv:1801.08127 [hep-ph]

    Pith/arXiv arXiv 2018

  10. [18]

    Quantum Mechanics of Gravitational Waves,

    M. Parikh, F. Wilczek, and G. Zahariade, “Quantum Mechanics of Gravitational Waves,”Phys. Rev. Lett.127no. 8, (2021) 081602,arXiv:2010.08205 [hep-th]

    Pith/arXiv arXiv 2021

  11. [19]

    Detecting single gravitons with quantum sensing,

    G. Tobar, S. K. Manikandan, T. Beitel, and I. Pikovski, “Detecting single gravitons with quantum sensing,”Nature Commun.15no. 1, (2024) 7229,arXiv:2308.15440 [quant-ph]

    Pith/arXiv arXiv 2024

  12. [20]

    Stimulated Emission or Absorption of Gravitons by Light,

    R. Sch¨ utzhold, “Stimulated Emission or Absorption of Gravitons by Light,”Phys. Rev. Lett.135 no. 17, (2025) 171501,arXiv:2502.10221 [gr-qc]

    Pith/arXiv arXiv 2025

  13. [21]

    Mandel and E

    L. Mandel and E. Wolf,Optical Coherence and Quantum Optics. Cambridge University Press, 1995

    1995

  14. [22]

    Loudon,The Quantum Theory of Light

    R. Loudon,The Quantum Theory of Light. OUP Oxford, 2000

    2000

  15. [23]

    Barnett and P

    S. Barnett and P. M. Radmore,Methods in Theoretical Quantum Optics, vol. 15 ofOxford Series in Optical and Imaging Sciences. Oxford University Press, 2002

    2002

  16. [24]

    Quantum description of wave dark matter,

    D. Y. Cheong, N. L. Rodd, and L.-T. Wang, “Quantum description of wave dark matter,”Phys. Rev. D111no. 1, (2025) 015028,arXiv:2408.04696 [hep-ph]. [25]HA YST ACCollaboration, M. J. Jewellet al., “New results from HAYSTAC’s phase II operation with a squeezed state receiver,”Phys. Rev. D107no. 7, (2023) 072007, arXiv:2301.09721 [hep-ex]

    Pith/arXiv arXiv 2025

  17. [26]

    Dark Matter Axion Search with HAYSTAC Phase II,

    HA YST ACCollaboration, X. Baiet al., “Dark Matter Axion Search with HAYSTAC Phase II,” Phys. Rev. Lett.134no. 15, (2025) 151006,arXiv:2409.08998 [hep-ex]

    Pith/arXiv arXiv 2025

  18. [27]

    First Results from an Axion Haloscope at CAPP around 10.7µeV,

    CAPPCollaboration, O. Kwonet al., “First Results from an Axion Haloscope at CAPP around 10.7µeV,”Phys. Rev. Lett.126no. 19, (2021) 191802,arXiv:2012.10764 [hep-ex]

    Pith/arXiv arXiv 2021

  19. [28]

    Extensive Search for Axion Dark Matter over 1 GHz with CAPP’S Main Axion Experiment,

    CAPPCollaboration, S. Ahnet al., “Extensive Search for Axion Dark Matter over 1 GHz with CAPP’S Main Axion Experiment,”Phys. Rev. X14no. 3, (2024) 031023,arXiv:2402.12892 [hep-ex]

    Pith/arXiv arXiv 2024

  20. [29]

    Extended Haloscope Search and Exclusion of a Candidate Signal near 1.036 GHz,

    S. Ahnet al., “Extended Haloscope Search and Exclusion of a Candidate Signal near 1.036 GHz,” Phys. Rev. Lett.137no. 2, (2026) 021803,arXiv:2602.05388 [hep-ex]. – 54 –

    arXiv 2026

  21. [30]

    Coherent and incoherent states of the radiation field,

    R. J. Glauber, “Coherent and incoherent states of the radiation field,”Phys. Rev.131(1963) 2766

    1963

  22. [31]

    Equivalence of semiclassical and quantum mechanical descriptions of statistical light beams,

    E. C. G. Sudarshan, “Equivalence of semiclassical and quantum mechanical descriptions of statistical light beams,”Phys. Rev. Lett.10(1963) 277

    1963

  23. [32]

    Universal quantum computation with ideal Clifford gates and noisy ancillas,

    S. Bravyi and A. Kitaev, “Universal quantum computation with ideal Clifford gates and noisy ancillas,”Phys. Rev. A71no. 2, (2005) 022316,arXiv:quant-ph/0403025

    Pith/arXiv arXiv 2005

  24. [33]

    Intrinsically Quantum Effects of Axion Dark Matter Are Undetectable,

    Y. Bao, D. Y. Cheong, N. L. Rodd, J. Takach, L.-T. Wang, and K. Zhou, “Intrinsically Quantum Effects of Axion Dark Matter Are Undetectable,”Phys. Rev. Lett.136no. 17, (2026) 171601, arXiv:2510.05198 [hep-ph]

    arXiv 2026

  25. [34]

    Seamless High-Q Microwave Cavities for Multimode Circuit Quantum Electrodynamics,

    S. Chakram, A. E. Oriani, R. K. Naik, A. V. Dixit, K. He, A. Agrawal, H. Kwon, and D. I. Schuster, “Seamless High-Q Microwave Cavities for Multimode Circuit Quantum Electrodynamics,”Phys. Rev. Lett.127no. 10, (2021) 107701

    2021

  26. [35]

    Searching for Dark Matter with a Superconducting Qubit,

    A. V. Dixit, S. Chakram, K. He, A. Agrawal, R. K. Naik, D. I. Schuster, and A. Chou, “Searching for Dark Matter with a Superconducting Qubit,”Phys. Rev. Lett.126no. 14, (2021) 141302,arXiv:2008.12231 [hep-ex]. [36]RADESCollaboration, Y. Gu, “Dark matter detection with superconducting qubit in RADES experiment,”PoSCOSMICWISPers2024(2025) 067

    Pith/arXiv arXiv 2021

  27. [37]

    Stimulated Emission of Signal Photons from Dark Matter Waves,

    A. Agrawal, A. V. Dixit, T. Roy, S. Chakram, K. He, R. K. Naik, D. I. Schuster, and A. Chou, “Stimulated Emission of Signal Photons from Dark Matter Waves,”Phys. Rev. Lett.132no. 14, (2024) 140801,arXiv:2305.03700 [quant-ph]

    arXiv 2024

  28. [38]

    Quantum-Enhanced Dark Matter Search Using Cat States,

    P. Zhenget al., “Quantum-Enhanced Dark Matter Search Using Cat States,”Phys. Rev. Lett. 136no. 17, (2026) 171002,arXiv:2507.23538 [quant-ph]

    Pith/arXiv arXiv 2026

  29. [39]

    Continuous measurement of quantum axion dark matter

    Y. Bao, D. Y. Cheong, N. L. Rodd, J. Takach, L.-T. Wang, and K. Zhou, “Continuous measurement of quantum axion dark matter.” 2026. To appear

    2026

  30. [40]

    Graviton detection and the quantization of gravity,

    D. Carney, V. Domcke, and N. L. Rodd, “Graviton detection and the quantization of gravity,” Phys. Rev. D109no. 4, (2024) 044009,arXiv:2308.12988 [hep-th]

    Pith/arXiv arXiv 2024

  31. [41]

    Comments on Graviton Detection,

    D. Carney, “Comments on Graviton Detection,” inProceedings of Gravity, Strings and Fields: A Conference in Honour of Gordon Semenoff, CRM Series in Mathematical Physics, pp. 11–28. Springer Cham, 2025.arXiv:2408.00094 [gr-qc]

    arXiv 2025

  32. [42]

    B. M. Brubaker,First results from the HAYSTAC axion search. PhD thesis, Yale U., 2017. arXiv:1801.00835 [astro-ph.CO]

    Pith/arXiv arXiv 2017

  33. [43]

    Gravitational focusing of wave dark matter,

    H. Kim and A. Lenoci, “Gravitational focusing of wave dark matter,”Phys. Rev. D105no. 6, (2022) 063032,arXiv:2112.05718 [hep-ph]

    Pith/arXiv arXiv 2022

  34. [44]

    A generic formation mechanism of ultralight dark matter solar halos,

    D. Budker, J. Eby, M. Gorghetto, M. Jiang, and G. Perez, “A generic formation mechanism of ultralight dark matter solar halos,”JCAP12(2023) 021,arXiv:2306.12477 [hep-ph]

    Pith/arXiv arXiv 2023

  35. [45]

    Cosmic axion background,

    J. A. Dror, H. Murayama, and N. L. Rodd, “Cosmic axion background,”Phys. Rev. D103no. 11, (2021) 115004,arXiv:2101.09287 [hep-ph]. [Erratum: Phys.Rev.D 106, 119902 (2022)]. [46]ADMXCollaboration, T. Nittaet al., “Search for a Dark-Matter-Induced Cosmic Axion Background with ADMX,”Phys. Rev. Lett.131no. 10, (2023) 101002,arXiv:2303.06282 [hep-ex]. – 55 –

    Pith/arXiv arXiv 2021

  36. [47]

    Quasiprobabilities for multipartite quantum correlations of light,

    E. Agudelo, J. Sperling, and W. Vogel, “Quasiprobabilities for multipartite quantum correlations of light,”Phys. Rev. A87(Mar, 2013) 033811

    2013

  37. [48]

    A quantum-mechanical central limit theorem,

    C. D. Cushen and R. L. Hudson, “A quantum-mechanical central limit theorem,”J. Appl. Probab.8no. 3, (1971) 454–469

    1971

  38. [49]

    Convergence rates for the quantum central limit theorem,

    S. Becker, N. Datta, L. Lami, and C. Rouz´ e, “Convergence rates for the quantum central limit theorem,”Commun. Math. Phys.383(2021) 223–279,arXiv:1912.06129 [quant-ph]

    Pith/arXiv arXiv 2021

  39. [50]

    Quantum Entropy and Central Limit Theorem,

    K. Bu, W. Gu, and A. Jaffe, “Quantum Entropy and Central Limit Theorem,”Proc. Nat. Acad. Sci.120(2023) e2304589120,arXiv:2302.07841 [quant-ph]

    Pith/arXiv arXiv 2023

  40. [51]

    Theory of electromagnetic field measurement and photoelectron counting,

    P. L. Kelley and W. H. Kleiner, “Theory of electromagnetic field measurement and photoelectron counting,”Phys. Rev.136(Oct, 1964) A316–A334

    1964

  41. [52]

    Atomic coherent states in quantum optics,

    F. T. Arecchi, E. Courtens, R. Gilmore, and H. Thomas, “Atomic coherent states in quantum optics,”Phys. Rev. A6(Dec, 1972) 2211–2237

    1972

  42. [53]

    Nonclassical character of states exhibiting no squeezing or sub-Poissonian statistics,

    G. S. Agarwal and K. Tara, “Nonclassical character of states exhibiting no squeezing or sub-Poissonian statistics,”Phys. Rev. A46(Jul, 1992) 485–488

    1992

  43. [54]

    On Information and Sufficiency,

    S. Kullback and R. A. Leibler, “On Information and Sufficiency,”Ann. Math. Statist.22no. 1, (1951) 79–86

    1951

  44. [55]

    T. M. Cover and J. A. Thomas,Elements of Information Theory. Wiley, 2005

    2005

  45. [56]

    Ordered expansions in boson amplitude operators,

    K. E. Cahill and R. J. Glauber, “Ordered expansions in boson amplitude operators,”Phys. Rev. 177(Jan, 1969) 1857–1881

    1969

  46. [57]

    Conservation laws and nonclassical states in nonlinear optical systems,

    M. Hillery, “Conservation laws and nonclassical states in nonlinear optical systems,”Phys. Rev. A31(Jan, 1985) 338–342

    1985

  47. [58]

    Nonclassical characteristics of the marginals for the radiation field,

    G. Agarwal, “Nonclassical characteristics of the marginals for the radiation field,”Opt. Commun. 95no. 1, (1993) 109–112

    1993

  48. [59]

    Nonclassicality criteria in terms of moments,

    E. Shchukin, T. Richter, and W. Vogel, “Nonclassicality criteria in terms of moments,”Phys. Rev. A71(Jan, 2005) 011802

    2005

  49. [60]

    Higher-order criteria for nonclassical effects in photon statistics,

    C. T. Lee, “Higher-order criteria for nonclassical effects in photon statistics,”Phys. Rev. A41 (Feb, 1990) 1721–1723

    1990

  50. [61]

    Many-photon antibunching in generalized pair coherent states,

    C. T. Lee, “Many-photon antibunching in generalized pair coherent states,”Phys. Rev. A41 (Feb, 1990) 1569–1575

    1990

  51. [62]

    Observable signs of nonclassical light,

    D. Klyshko, “Observable signs of nonclassical light,”Phys. Lett. A213no. 1, (1996) 7–15

    1996

  52. [63]

    Nonclassical moments and their measurement,

    E. V. Shchukin and W. Vogel, “Nonclassical moments and their measurement,”Phys. Rev. A72 (Oct, 2005) 043808

    2005

  53. [64]

    Phase-space inequalities beyond negativities,

    M. Bohmann and E. Agudelo, “Phase-space inequalities beyond negativities,”Phys. Rev. Lett. 124(Mar, 2020) 133601

    2020

  54. [65]

    Verifying single-mode nonclassicality beyond negativity in phase space,

    J. Park, J. Lee, and H. Nha, “Verifying single-mode nonclassicality beyond negativity in phase space,”Phys. Rev. Res.3(Nov, 2021) 043116

    2021

  55. [66]

    Nonclassical effects in phase space,

    N. L¨ utkenhaus and S. M. Barnett, “Nonclassical effects in phase space,”Phys. Rev. A51(Apr,

  56. [67]

    Quasi-probability representations of quantum theory with applications to quantum information science,

    C. Ferrie, “Quasi-probability representations of quantum theory with applications to quantum information science,”Rept. Prog. Phys.74no. 11, (2011) 116001,arXiv:1010.2701 [quant-ph]

    Pith/arXiv arXiv 2011

  57. [68]

    Negative quasi-probability as a resource for quantum computation,

    V. Veitch, C. Ferrie, D. Gross, and J. Emerson, “Negative quasi-probability as a resource for quantum computation,”New J. Phys.14no. 11, (2012) 113011, arXiv:1201.1256 [quant-ph]

    Pith/arXiv arXiv 2012

  58. [69]

    Positive Wigner Functions Render Classical Simulation of Quantum Computation Efficient,

    A. Mari and J. Eisert, “Positive Wigner Functions Render Classical Simulation of Quantum Computation Efficient,”Phys. Rev. Lett.109no. 23, (2012) 230503,arXiv:1208.3660 [quant-ph]

    Pith/arXiv arXiv 2012

  59. [70]

    Quantifying the magic of quantum channels,

    X. Wang, M. M. Wilde, and Y. Su, “Quantifying the magic of quantum channels,”New J. Phys. 21no. 10, (2019) 103002,arXiv:1903.04483 [quant-ph]

    Pith/arXiv arXiv 2019

  60. [71]

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

    2010

  61. [72]

    Detecting Hidden Photon Dark Matter Using the Direct Excitation of Transmon Qubits,

    S. Chen, H. Fukuda, T. Inada, T. Moroi, T. Nitta, and T. Sichanugrist, “Detecting Hidden Photon Dark Matter Using the Direct Excitation of Transmon Qubits,”Phys. Rev. Lett.131 no. 21, (2023) 211001,arXiv:2212.03884 [hep-ph]

    Pith/arXiv arXiv 2023

  62. [73]

    Quantum Enhancement in Dark Matter Detection with Quantum Computation,

    S. Chen, H. Fukuda, T. Inada, T. Moroi, T. Nitta, and T. Sichanugrist, “Quantum Enhancement in Dark Matter Detection with Quantum Computation,”Phys. Rev. Lett.133no. 2, (2024) 021801,arXiv:2311.10413 [hep-ph]

    Pith/arXiv arXiv 2024

  63. [74]

    Quantum entanglement of ions for light dark matter detection,

    A. Ito, R. Kitano, W. Nakano, and R. Takai, “Quantum entanglement of ions for light dark matter detection,”JHEP02(2024) 124,arXiv:2311.11632 [hep-ph]

    Pith/arXiv arXiv 2024

  64. [75]

    Search for QCD axion dark matter with transmon qubits and quantum circuit,

    S. Chen, H. Fukuda, T. Inada, T. Moroi, T. Nitta, and T. Sichanugrist, “Search for QCD axion dark matter with transmon qubits and quantum circuit,”Phys. Rev. D110no. 11, (2024) 115021,arXiv:2407.19755 [hep-ph]

    arXiv 2024

  65. [76]

    Directional Searching for Light Dark Matter with Quantum Sensors,

    H. Fukuda, Y. Matsuzaki, and T. Sichanugrist, “Directional Searching for Light Dark Matter with Quantum Sensors,”Phys. Rev. Lett.135no. 24, (2025) 241802,arXiv:2506.19614 [hep-ph]

    Pith/arXiv arXiv 2025

  66. [77]

    On the Speed-up of Wave-like Dark Matter Searches with Entangled Qubits,

    A. Bodas, S. Ghosh, and R. Harnik, “On the Speed-up of Wave-like Dark Matter Searches with Entangled Qubits,”arXiv:2510.11795 [hep-ph]

    arXiv

  67. [78]

    Confirming entanglement in continuous variable quantum teleportation,

    S. M. Tan, “Confirming entanglement in continuous variable quantum teleportation,”Phys. Rev. A60(Oct, 1999) 2752–2758

    1999

  68. [79]

    Peres-Horodecki Separability Criterion for Continuous Variable Systems,

    R. Simon, “Peres-Horodecki Separability Criterion for Continuous Variable Systems,”Phys. Rev. Lett.84(Mar, 2000) 2726–2729

    2000

  69. [80]

    Entanglement conditions for two-mode states,

    M. Hillery and M. S. Zubairy, “Entanglement conditions for two-mode states,”Phys. Rev. Lett. 96(Feb, 2006) 050503

    2006

  70. [81]

    Inseparability criterion for continuous variable systems,

    L.-M. Duan, G. Giedke, J. I. Cirac, and P. Zoller, “Inseparability criterion for continuous variable systems,”Phys. Rev. Lett.84(Mar, 2000) 2722–2725

    2000

  71. [82]

    Dark Matter Interferometry,

    J. W. Foster, Y. Kahn, R. Nguyen, N. L. Rodd, and B. R. Safdi, “Dark Matter Interferometry,” Phys. Rev. D103no. 7, (2021) 076018,arXiv:2009.14201 [hep-ph]

    Pith/arXiv arXiv 2021

  72. [83]

    Direct detection of classically undetectable dark matter through quantum decoherence,

    C. J. Riedel, “Direct detection of classically undetectable dark matter through quantum decoherence,”Phys. Rev. D88no. 11, (2013) 116005,arXiv:1212.3061 [quant-ph]. – 57 –

    Pith/arXiv arXiv 2013

  73. [84]

    Decoherence as a way to measure extremely soft collisions with dark matter,

    C. J. Riedel and I. Yavin, “Decoherence as a way to measure extremely soft collisions with dark matter,”Phys. Rev. D96no. 2, (2017) 023007,arXiv:1609.04145 [quant-ph]

    Pith/arXiv arXiv 2017

  74. [85]

    Atom interferometer tests of dark matter,

    Y. Du, C. Murgui, K. Pardo, Y. Wang, and K. M. Zurek, “Atom interferometer tests of dark matter,”Phys. Rev. D106no. 9, (2022) 095041,arXiv:2205.13546 [hep-ph]

    Pith/arXiv arXiv 2022

  75. [86]

    Coherent collisional decoherence,

    L. Badurina, C. Murgui, and R. Plestid, “Coherent collisional decoherence,”Phys. Rev. A110 no. 3, (2024) 033311,arXiv:2402.03421 [quant-ph]

    Pith/arXiv arXiv 2024

  76. [87]

    Matter-Wave Interferometers as Open-System Dark Matter Detectors,

    L. Badurina and K. M. Zurek, “Matter-Wave Interferometers as Open-System Dark Matter Detectors,”arXiv:2606.00237 [hep-ph]

    Pith/arXiv arXiv

  77. [88]

    Ultralight dark matter detection with trapped-ion interferometry,

    L. Badurina, D. Blas, J. Ellis, and S. A. R. Ellis, “Ultralight dark matter detection with trapped-ion interferometry,”Phys. Rev. D113no. 9, (2026) 092004,arXiv:2507.17825 [hep-ph]

    Pith/arXiv arXiv 2026

  78. [89]

    How squeezed states both maximize and minimize the same notion of quantumness,

    A. Z. Goldberg and K. Heshami, “How squeezed states both maximize and minimize the same notion of quantumness,”Phys. Rev. A104(2021) 032425,arXiv:2106.03862 [quant-ph]

    Pith/arXiv arXiv 2021

  79. [90]

    Measuring Decoherence Due to Quantum Vacuum Fluctuations,

    A. Gundhi and H. Ulbricht, “Measuring Decoherence Due to Quantum Vacuum Fluctuations,” Phys. Rev. Lett.135no. 2, (2025) 020402,arXiv:2501.17928 [quant-ph]

    Pith/arXiv arXiv 2025

  80. [91]

    General Relativistic Decoherence with Applications to Dark Matter Detection,

    I. J. Allali and M. P. Hertzberg, “General Relativistic Decoherence with Applications to Dark Matter Detection,”Phys. Rev. Lett.127no. 3, (2021) 031301,arXiv:2103.15892 [gr-qc]

    Pith/arXiv arXiv 2021

Showing first 80 references.