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Quantum oscillations of the rectified voltage and the critical current of asymmetric mesoscopic superconducting loops

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V.L. Gurtovoi, S.V. Dubonos, A.V. Nikulov, N.N. Osipov, V.A. Tulin

Superconductivity · Submitted 28 Feb 2006 · 13 references

Pith's verdict: A solid experimental follow-up that supplies direct evidence for the group's rectification explanation of dc voltage oscillations in asymmetric loops, though the mechanism remains correlationally supported rather than quantitatively proven.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 28, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

  1. T0 AI review An AI read the paper and answered a fixed list of questions.
  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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arXiv IDcond-mat/0602677 (version 1)
Pith IDDHOZTPJX, Pith's permanent record of this paper and its review
CitationA.V. Nikulov, N.N. Osipov, S.V. Dubonos, V.A. Tulin, V.L. Gurtovoi. "Quantum oscillations of the rectified voltage and the critical current of asymmetric mesoscopic superconducting loops." arXiv:cond-mat/0602677 (2006). https://pith.science/paper/DHOZTPJX
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The paper

The paper claims

Asymmetric superconducting loops rectify alternating current into a flux-oscillating dc voltage.

The reading

This paper argues that the quantum oscillations of dc voltage seen on segments of asymmetric superconducting loops are not a direct voltage produced by the persistent current. Instead, the loop's current-voltage curve is asymmetric: the critical current in one direction differs from the other, and that difference changes sign and magnitude periodically with magnetic flux. When an alternating current or noise drives the loop, this asymmetric curve acts like a rectifier and produces a dc voltage whose sign and size track the critical-current anisotropy. The authors support this by measuring $I_{c,+}$ and $I_{c,-}$ in opposite directions and showing that $V_{\mathrm{dc}}(B)$ mirrors $-I_{c,\mathrm{an}}(B)$. If the explanation is right, the oscillation is explained by an ordinary rectification effect, and a similar response is not excluded in normal-metal or semiconductor loops that carry persistent currents.

What carries the argument

The load-bearing object is the critical-current anisotropy $I_{c,\mathrm{an}}(\Phi/\Phi_0) = I_{c,+}-I_{c,-}$, a flux-dependent asymmetry of the current-voltage characteristic that arises because the persistent current adds to or opposes the transport current in the two directions. The rectification step is the time average of the nonlinear I-V curve under a sinusoidal drive, $V_{\mathrm{dc}} = \Theta^{-1}\int_0^\Theta V(I_0\sin 2\pi f t)\,dt$, which is nonzero only when the I-V curve is asymmetric and $I_0$ exceeds one critical current but not the other. The comparison between $V_{\mathrm{dc}}(\Phi/\Phi_0)$ and $-I_{c,\mathrm{an}}(\Phi/\Phi_0)$ is what carries the argument.

Extended reading notes

Core claim

The paper reports that in asymmetric aluminum loops, the critical currents in opposite directions, $I_{c,+}(\Phi/\Phi_0)$ and $I_{c,-}(\Phi/\Phi_0)$, are both periodic in magnetic flux with period $\Phi_0$, but shifted relative to each other by a constant $\Delta\varphi$. Their difference $I_{c,\mathrm{an}} = I_{c,+}-I_{c,-}$ therefore oscillates in sign and magnitude with flux. The rectified dc voltage $V_{\mathrm{dc}}$ produced by an external ac current has a magnetic-field dependence that mirrors $-I_{c,\mathrm{an}}$, in single loops, systems of 20 identical loops, and non-periodic double loops. The authors take this as confirmation that the quantum oscillations of $V_{\mathrm{dc}}$ are a rectification effect: the flux-asymmetric current-voltage curve time-averages a sinusoidal current into a dc voltage when the current amplitude lies between the two critical currents. They also note that the rectified signal is strongest when the I-V curve is irreversible, and that persistent currents exist in normal and semiconductor loops as well, so a similar effect is not excluded there.

Load-bearing premise

The load-bearing premise is that the observed similarity between $V_{\mathrm{dc}}(B)$ and $-I_{c,\mathrm{an}}(B)$ is sufficient to identify rectification as the cause, without a quantitative reconstruction of $V_{\mathrm{dc}}$ from the measured I-V curves or explicit exclusion of flux-dependent asymmetries in the contacts and leads.

Editorial extensions

If this is right

  • The quantum oscillations of $V_{\mathrm{dc}}$ observed in earlier experiments require no new voltage-generation mechanism; they follow from ordinary rectification of an ac current or noise by a flux-dependent asymmetric I-V curve.
  • The sign of the rectified voltage is controlled by the critical-current anisotropy $I_{c,+}-I_{c,-}$, so measuring the two critical currents is sufficient to predict where $V_{\mathrm{dc}}$ changes sign.
  • Rectification is most efficient when the I-V curve is irreversible, and the amplitude of the rectified voltage is largest when the ac drive amplitude lies between the two critical currents.
  • The same $V_{\mathrm{dc}}(B)$ versus $-I_{c,\mathrm{an}}(B)$ relation holds for non-periodic double loops, showing the explanation does not depend on exact flux-quantum periodicity.
  • Because the asymmetry ultimately comes from the persistent current, the rectified voltage provides a readout of persistent-current oscillations in an asymmetric loop.

Reading between the lines

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

  • A direct quantitative test of the paper's explanation would be to reconstruct $V_{\mathrm{dc}}$ by time-averaging the measured I-V curves for the same drive amplitude and frequency; the paper does not perform this calculation, so the similarity argument leaves that gap open.
  • Since persistent currents also exist above $T_c$ and in normal-metal and semiconductor rings, the rectification mechanism may carry over to those systems, but the smooth and reversible I-V curves expected there would make the rectified signal far weaker than in the low-temperature superconducting case.
  • The pronounced efficiency of rectification in the irreversible regime suggests that asymmetric superconducting loops could act as flux-sensitive detectors whose gain is set by the drive amplitude and the steepness of the resistive transition.
Original abstract

The current-voltage curves and magnetic dependence of the critical current of asymmetric superconducting loops are measured. It was found that sign and value of the asymmetry of the current-voltage curves changes with value of magnetic field, periodically for single loop and system of identical loops. The obtained results allow to explain the quantum oscillation of the dc voltage, observed below superconducting transition in the previous works, as rectification of ac current or noise.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 2,969 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.06 · human participants 0.01 · controlled comparison 0.07 · randomized assignment 0.01 · states quantitative result 0.07 · compares with prior results 0.81 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

The current-voltage curves and magnetic dependence of the critical current of asymmetric superconducting loops are measured. It was found that sign and value of the asymmetry of the current-voltage curves changes with value of magnetic field, periodically for single loop and system of identical loops. The obtained results allow to explain the quantum oscillation of the dc voltage, observed below superconducting transition in the previous works, as rectification of ac current or noise.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 The current-voltage curves and magnetic dependence of the critical current of asymmetric superconducting loops are measured. method 0.72 0.93 0.04 asserted 1.00
s1 It was found that sign and value of the asymmetry of the current-voltage curves changes with value of magnetic field, periodically for single loop and system of identical loops. result 1.00 0.94 0.38 asserted 1.00
s2 The obtained results allow to explain the quantum oscillation of the dc voltage, observed below superconducting transition in the previous works, as rectification of ac current or noise. interpretation 1.00 0.47 0.78 asserted 0.72

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. FIG. 1: An SEM photo of the asymmetric aluminum round
Figure 2. FIG. 2: The quantum oscillations of the critical current
Figure 3. FIG. 3: The magnetic dependencies of the critical cur

Figures reproduced from arXiv:cond-mat/0602677 by the authors.

References
How the literature uses it

1 arXiv paper cite this in 1 sentence

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers whose main result relates to this one's

Found among the papers closest to this one by title and main claim. Pith's classifier compared each pair's main results and a second model family confirmed the relation; checked against two further families, shown conflicts agreed 118 times in 120 and shown same results 218 times in 239. The quoted sentence is the other paper's main claim.

States the same result 2 papers

Discussion

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