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REVIEW 1 major objections 2 minor 21 references

Early Experiments on Macroscopic Quantum Tunneling

T0 review · 1 major / 2 minor · reviewed 2026-06-28 · grok-4.3

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Pith's one-line read The first experimental results interpreted as macroscopic quantum tunneling came from 1979 Leiden studies on niobium point contacts in rf SQUIDs.

desk verdict This is a short historical review arguing that 1979 Leiden Nb point-contact rf-SQUID data were the first interpreted as MQT, but it adds no new analysis or data checks. read the letter →

arxiv 2606.02770 v1 pith:HGKZ6QWD submitted 2026-06-01 cond-mat.supr-con

Willem den Boer This is my paper · ORCID
classification cond-mat.supr-con
keywords macroscopicquantumtunnelingJosephsonjunctionrfSQUIDniobiumpointcontactLeidenexperimentssuperconductingweaklinkescaperate
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

The paper reviews the earliest experiments interpreted as evidence for macroscopic quantum tunneling, performed at Leiden University in 1979 using low-capacitance niobium point contacts in an rf SQUID configuration at temperatures from 1 to 4.2 K. These results were published in 1980 and drew on 1969 predictions for current-biased Josephson junctions and 1978 predictions for closed superconducting loops. The work places these observations in the timeline before the 1985 experiments that provided more conclusive evidence. A sympathetic reader would care because the paper reconstructs how macroscopic quantum effects were first accessed experimentally in superconducting weak links.

What carries the argument

Low-capacitance niobium point contacts arranged in an rf SQUID configuration, which enabled observation of escape rates from the zero-voltage state at temperatures where tunneling could be distinguished from thermal activation.

What would settle it

Access to the original raw data from the 1979 Leiden experiments showing temperature-dependent escape rates fully consistent with thermal activation and no temperature-independent regime.

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Extended reading notes

Core claim

The central claim is that the first experimental results interpreted as MQT were reported in 1980 based on studies done at Leiden University in 1979 on low capacitance Niobium point contacts in an rf SQUID configuration.

Load-bearing premise

The 1979-1980 Leiden experimental data can be accurately reconstructed and interpreted as MQT using the theoretical frameworks cited without access to original raw data or modern re-analysis.

Editorial extensions

If this is right

  • The 1980 Leiden report constitutes the chronologically first published interpretation of MQT in Josephson systems.
  • The rf SQUID geometry with point-contact weak links allowed access to the low capacitance regime needed for observable quantum escape.
  • Data taken between 1 and 4.2 K provided the temperature window used to separate tunneling from classical thermal activation.
  • The observations were framed using the 1969 Ivanchenko-Zilberman model for biased junctions and the 1978 Leggett model for closed loops.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Re-examination of similar historical Josephson data with present-day noise characterization could test the original tunneling assignment.
  • The early reliance on point contacts shows how junction capacitance directly controls visibility of macroscopic quantum effects.
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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

1 major / 2 minor

Summary. The paper claims that the first experimental results interpreted as Macroscopic Quantum Tunneling (MQT) were reported in 1980 from 1979 studies at Leiden University on low-capacitance Niobium point contacts in an rf SQUID configuration at 1-4.2 K. These preceded the 1985 Clarke-Devoret-Martinis work and were inspired by Ivanchenko-Zilberman (1969) predictions for current-biased Josephson junctions and Leggett (1978) on closed loops with weak links. The manuscript offers a historical retrospective on these early experiments.

Significance. If the chronological and interpretive claims hold, the paper provides archival value by documenting preliminary MQT efforts in superconducting systems and crediting the Leiden group's contributions to the field's early history. It highlights the transition from 1969-1978 theory to experiment but introduces no new data, re-analysis, or falsifiable predictions, limiting its impact to historiography rather than advancing current understanding of MQT.

major comments (1)
  1. [Abstract] Abstract: The central claim that the 1979 Leiden Nb point-contact rf-SQUID data constitute the first MQT observations requires that the observed switching statistics exhibit the predicted signatures (temperature-independent escape rate below crossover T, consistent with Ivanchenko-Zilberman and Leggett models) rather than thermal activation. The manuscript provides no original I-V traces, switching histograms, parameter extraction, or quantitative comparison from the 1979 run, leaving the mapping from raw observations to MQT as an unverified assertion.
minor comments (2)
  1. The manuscript should include explicit references to the 1980 publication reporting the Leiden results and any contemporary discussions of their interpretation.
  2. Clarify the source material for the historical account (e.g., published records only, or access to lab notes) to allow readers to assess the strength of the retrospective MQT assignment.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading of our historical review manuscript. The comment correctly identifies that the paper does not re-present or quantitatively re-analyze the original 1979 data. We address this below and indicate the revisions we will make.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The central claim that the 1979 Leiden Nb point-contact rf-SQUID data constitute the first MQT observations requires that the observed switching statistics exhibit the predicted signatures (temperature-independent escape rate below crossover T, consistent with Ivanchenko-Zilberman and Leggett models) rather than thermal activation. The manuscript provides no original I-V traces, switching histograms, parameter extraction, or quantitative comparison from the 1979 run, leaving the mapping from raw observations to MQT as an unverified assertion.

    Authors: We agree that the manuscript, as a historical retrospective, does not include the original I-V traces, switching histograms, or new quantitative comparisons from the 1979 Leiden experiments; such data would be outside the scope of a review documenting the sequence of interpretations in the published literature. The central claim is that the 1980 reports were the first to interpret the observations as MQT, drawing on the Ivanchenko-Zilberman and Leggett frameworks then available. To address the referee's point, we will revise the abstract and introduction to state explicitly that the paper records the historical interpretations advanced at the time rather than asserting or re-verifying the presence of the predicted MQT signatures. We will also add a sentence directing readers to the original 1980 publications for the detailed experimental records. revision: yes

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: historical narrative without derivations or load-bearing self-references

full rationale

The paper is a chronological historical review of 1979-1980 Leiden experiments on Nb point contacts, citing Ivanchenko-Zilberman (1969) and Leggett (1978) as inspirational theory. No equations, predictions, fitted parameters, or derivations appear. The central claim is a factual assertion about publication chronology and interpretation at the time; it does not reduce any result to its own inputs by construction, nor rely on self-citation chains for uniqueness or ansatz. External citations are to independent prior work and do not create circularity under the defined patterns.

Assumptions & free parameters 0 free parameters · 0 assumptions · 0 invented entities

The paper is a historical review and introduces no free parameters, axioms, or invented entities; all content draws from cited prior literature.

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Cite this review

Pith. "Pith review of Early Experiments on Macroscopic Quantum Tunneling." pith.science (2026). https://pith.science/paper/HGKZ6QWD

@misc{pith2026260602770,
  author       = {Pith},
  title        = {Pith review of: Early Experiments on Macroscopic Quantum Tunneling},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/HGKZ6QWD}},
  note         = {Machine review of arXiv:2606.02770}
}
read the original abstract

Before conclusive evidence of Macroscopic Quantum Tunneling, MQT, was published by Clarke, Devoret and Martinis in 1985, several other groups reported experimental results interpreted as MQT. The first, in chronological order, was in 1980 based on studies done at Leiden University in 1979. This paper looks back at these experiments on low capacitance Niobium point contacts in an rf SQUID, radio-frequency Superconducting Quantum Interference Device, configuration at temperatures between 1 and 4.2 K. The research was inspired by the theoretical predictions by Ivanchenko and Zilberman in 1969 on MQT in current-biased Josephson junctions and by Leggett in 1978 on MQT in closed loops with a superconducting weak link.

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

21 extracted references · 1 canonical work pages

  1. [1]

    Devoret, J.M

    M.H. Devoret, J.M. Martinis, and J. Clarke. Mea- surement of macroscopic quantum tunneling out of a zero-voltage state of a current-biased josephson junc- tion.Phys. Rev. Lett., 55:1908–1911, 1985

    1908

  2. [2]

    Martinis, M.H

    J.M. Martinis, M.H. Devoret, and J. Clarke. Energy- level quantization in the zero-voltage state of a current- biased josephson junction.Phys. Rev. Lett., 55:1543– 1546, 1985

    1985

  3. [3]

    Ivanchenko and L.A

    Y .M. Ivanchenko and L.A. Zil’berman. The joseph- son effect in small tunnel contacts.Sov. Phys. JETP, 28(6):1272–1276, 1969

    1969

  4. [4]

    A.J. Leggett. Prospects in ultralow temperature physics. J. Phys. Colloques, 39(C6):1264–1269, 1978

    1978

  5. [5]

    V oss and R.A

    R.F. V oss and R.A. Webb. Macroscopic quantum tun- neling in 1-µm nb josephson junctions.Phys. Rev. Lett., 47:265–268, 1981

    1981

  6. [6]

    Jackel, J.P

    L.D. Jackel, J.P. Gordon, E.L. Hu, R.E. Howard, L.A. Fetter, D.M. Tennant, R.W. Epworth, and J. Kurkijarvi. Decay of the zero-voltage state in small-area, high- current-density josephson junctions.Phys. Rev. Lett., 47:697–700, 1981

    1981

  7. [7]

    den Boer and R

    W. den Boer and R. de Bruyn Ouboter. Flux transi- tion mechanisms in superconducting loops closed with a low capacitance point contact.Physica B+C, 98(3):185– 191, 1980

    1980

  8. [8]

    Prance, A.P

    R.J. Prance, A.P. Long, T.D. Clarke, A. Widom, J.E. Mutton, J. Sacco, M.W. Potts, G. Megaloudis, and F. Goodall. Macroscopic quantum electrodynamic ef- fects in a superconducting ring containing a josephson weak link.Nature, 289:543–549, 1981

    1981

Show all 21 references
  1. [9]

    Turutanov

    O.G. Turutanov. Nobel prize and the contribution of ukrainian scientists to the understanding of quantum phenomena, in particular the behavior of macroscopic quantum systems (nobel prize in physics 2025).Visn. Nac. Akad. Nauk Ukr., 12:20–30, 2025

    2025

  2. [10]

    de Bruyn Ouboter

    R. de Bruyn Ouboter. Heike kamerlingh onnes’s discovery of superconductivity.Scientific American, 276(3):98–103, 1997

    1997

  3. [11]

    de Bruyn Ouboter

    R. de Bruyn Ouboter. Superconductivity: Discoveries during the early years of low temperature research at leiden 1908–1914.IEEE Trans. Magn., 23(2):355–370, 1987. 6

    1908

  4. [12]

    T.P. Das, R. De Bruyn Ouboter, and K.W. Taconis. in proc. 9th int. conf. on low temp. phys. In J.G. Daunt, D.O. Edwards, F.J. Milford, and M. Yaqub, editors, Proc. 9th Int. Conf. on Low Temp. Phys., Columbus, Ohio, page 1253, New York, 1965. Plenum Press

    1965

  5. [13]

    Tolner and C.D

    H. Tolner and C.D. Andriesse. High impedance point contact josephson junctions.IEEE Trans. Magn., 11:866–870, 1975

    1975

  6. [14]

    Dmitrenko, G.M

    I.M. Dmitrenko, G.M. Tsoi, and V .I. Shnyrkov. Macro- scopic quantum tunneling in a system with dissipation. Sov. J. Low Temp. Phys., 8(6):330, 1982

    1982

  7. [15]

    Caldeira and A.J

    A.O. Caldeira and A.J. Leggett. Influence of dissipation on quantum tunneling in macroscopic systems.Phys. Rev. Lett., 46:211–214, 1981

    1981

  8. [16]

    Altimiras, D

    C. Altimiras, D. Esteve, C. Girit, H. le Sueur, and P. Joyez. Absence of a dissipative quan- tum phase transition in josephson junctions: Theory. arXiv:2312.14754v5 [cond-mat.supr-com] 15 Jan 2025, 2025

    2025

  9. [17]

    Murani, N

    A. Murani, N. Bourlet, H. le Sueur, F. Portier, C. Al- timiras, D. Esteve, H. Grabert, J. Stockburger, J. Anker- hold, and P. Joyez. Absence of a dissipative quantum phase transition in josephson junctions.Phys. Rev. X, 10(2):021003, 2020

    2020

  10. [18]

    Clarke, A.N

    J. Clarke, A.N. Cleland, M.H. Devoret, D. Esteve, and J.M. Martinis. Quantum mechanics of a macroscopic variable: The phase difference of a josephson junction. Science, 239:992–997, 1988

    1988

  11. [19]

    Nakamura, Yu.A

    Y . Nakamura, Yu.A. Pashkin, and J.S. Tsai. Coher- ent control of macroscopic quantum states in a single- cooper-pair box.Nature, 398:786–788, 1999

    1999

  12. [20]

    Mooij, T.P

    J.E. Mooij, T.P. Orlando, L. Levitov, L. Tian, C.H. van der Wal, and S. Lloyd. Josephson persistent-current qubit.Science, 285:1036–1039, 1999

    1999

  13. [21]

    den Boer.Active Matrix Liquid Crystal Displays: Fundamentals and Applications

    W. den Boer.Active Matrix Liquid Crystal Displays: Fundamentals and Applications. Newnes, a division of Elsevier, Oxford, 2005. 7

    2005

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