# Light-driven states: transient evidence and equilibrium limits

Compare optical, electrical and magnetic evidence under explicit drive conditions, with depth reconstruction, granularity and detection limits.

## Scope

Light can change carrier populations, excite lattice motion and alter collective electronic response. Persistent photodoping, a transient pump–probe state and a periodically driven model are different protocols. Specify wavelength, polarization, pulse duration, fluence, repetition rate, base temperature and probe delay. A temperature at which a driven response is observed is not automatically an equilibrium superconducting transition temperature. [R1](#ref-source-c60f0131e7d25c60) [R2](#ref-source-e8775e639989b8d6) [R4](#ref-source-6ee3670220e24ff1) [R6](#ref-source-30e68110da17974c)

The evidence now extends beyond optical conductivity. Electrical measurements in K3C60, transient magnetic measurements in YBa2Cu3O6.48 and a later sensitivity-limited magnetic experiment on K3C60 ask different questions. Preserve the specimen, geometry and measured observable rather than combining them into one universal light-induced transition. [R5](#ref-source-07be806c0002c690) [R9](#ref-source-65e69ec93039deb9) [R10](#ref-source-930b28b64275da42) [R11](#ref-source-e7138d083320dfd7)

## Mathematical assumptions

With the $e^{-i\omega t}$ convention, a normal Drude response is $\sigma(\omega)=D/(\Gamma-i\omega)$, where $D$ is the Drude weight and $\Gamma>0$ the relaxation rate. Thus $\sigma_2=D\omega/(\Gamma^2+\omega^2)\approx D/\omega$ when the measured frequencies greatly exceed $\Gamma$, although the DC conductivity $D/\Gamma$ remains finite. A finite-band inductive trend alone cannot distinguish this limit from a condensate. This elementary counterexample is not a fit to, or refutation of, any particular experiment. [R4](#ref-source-6ee3670220e24ff1) [R7](#ref-source-a85b56be7c62bf11)

Depth reconstruction also matters. For Dodge's illustrative saturating profile, $\Delta\sigma(z)=\Delta\sigma_{\rm sat}f e^{-z/\Lambda}/(1+f e^{-z/\Lambda})$, with $f=F/F_{\rm sat}$, integration gives sheet photoconductance $\Delta G=\Delta\sigma_{\rm sat}\Lambda\ln(1+f)$. The effective thickness grows with fluence even while the surface response saturates. Assuming a fixed exponential profile can therefore bias the inferred surface conductivity. This integral checks the stated profile, not a full electromagnetic inversion; the experimental interpretation is disputed below. [R7](#ref-source-a85b56be7c62bf11) [R8](#ref-source-56a2c1fa63bafe80)

Kennes's minimal quadratic electron–phonon model gives oscillator frequency $\omega(n)=\omega_0\sqrt{1+2gn}$ for site occupation $n=0,1,2$, requiring $g>-1/4$. At fixed phonon occupation $n_B$, its induced interaction is $\Delta U=(n_B+1/2)\hbar\omega_0[\sqrt{1+4g}+1-2\sqrt{1+2g}]$. Concavity makes this nonpositive for either sign of stable $g$, with leading term $-(n_B+1/2)\hbar\omega_0g^2$. The author manuscript sets Planck's constant to one; it is restored here. This is a model mechanism, not a measured coupling or proof of a stable superconducting phase. [R6](#ref-source-30e68110da17974c)

## Experimental criteria

Fausti studied stripe-ordered La1.675Eu0.2Sr0.125CuO4 at a 10 K base temperature. The reported signal is a transient c-axis plasma edge and optical response interpreted as restored interlayer coherence. Figures 2–3 specify a 16 micrometre pump, approximately 1 mJ/cm² fluence and a 5 ps delay for the transient spectrum. The pump excites roughly 200 nm in depth, while the THz probe samples about 10 micrometres; the transformed-layer reconstruction is essential. A near-infrared plateau observed to 100 ps does not directly measure a many-nanosecond lifetime. [R1](#ref-source-c60f0131e7d25c60)

Hu's YBa2Cu3O6.5 specimen has an equilibrium transition near 50 K. Its approximately 300 fs, 15 micrometre pump modifies both inter- and intra-bilayer optical response. The effective-medium analysis separates transformed and untransformed regions; screened plasma-edge positions are not the same as fitted unscreened plasma frequencies. Broadband data at 60 K and narrower-band measurements at 100 and 300 K have different information content. Mankowsky's associated structural study combines diffraction with calculations to connect driven distortions with electronic changes; structural response does not uniquely identify pairing. [R2](#ref-source-e8775e639989b8d6) [R3](#ref-source-b47831832e13ca4e)

Mitrano's K3C60 report compares a transient optical response above the roughly 20 K equilibrium transition with the low-temperature spectrum. Its title deliberately says “Possible”. The reported optical-gap fit and enhanced carrier mobility are not a direct DC resistance or magnetic measurement. Temperature, pump–probe delay and model-dependent gap extraction must remain attached to that evidence. [R4](#ref-source-6ee3670220e24ff1)

Budden extended the response using longer pulses. Figure 4 compares optical extrapolation with electrical measurements at a 100 K base temperature and about 25 mJ/cm² fluence. The optical and transport pump durations are 200 ps and 75 ps, respectively; the electrical voltage probe lasts 1 ns. The electrical experiment is transient two-terminal transport with contact contributions calibrated from static four-terminal measurements; it is not a direct transient four-terminal measurement. The optical error bars describe a fit confidence interval, while the transport shading estimates contact-calibration systematic error. Those uncertainties cannot be interchanged or discarded when assessing compatibility with zero. Recovery over tens of nanoseconds supports the authors' metastable interpretation without establishing a pump-free equilibrium transition at 100 K. The drive, probe and recovery times are different quantities. [R5](#ref-source-07be806c0002c690)

Adelinia's 2025 thin-film study uses a quasi-DC bias, 300 fs pulses at 7 micrometres and photoconductive switches to resolve voltage dynamics. Granular-film and powder results are not interchangeable. The above-transition voltage response changes sign at 80 K; at 100 K it is positive and linear across the measured current range. Fitted superfluid fractions and weak-link phase-slip dynamics depend on the granular two-fluid model. A 100 K measurement in this paper must not become a 100 K superconducting-transition record. [R10](#ref-source-930b28b64275da42)

Fava's 2024 YBa2Cu3O6.48 experiment detects a transient magnetic-field enhancement near the excited region's edge using Faraday rotation in a nearby GaP detector. Signals at 100 and 300 K last about 1 ps. The inferred diamagnetic susceptibility of order −0.3 depends on geometry and the magnetic-response model; the paper itself cautions that a quasi-static estimate is not fully justified for this dynamics. This provides a complementary magnetic observable, while remaining distinct from a persistent equilibrium Meissner state. [R9](#ref-source-65e69ec93039deb9)

De Vecchi's December 2025 K3C60 study used a 50 K base temperature, about 1 ps pulses at 8 micrometres, 40 mJ/cm² fluence and a 0.5 mT applied field. No statistically significant photo-induced field signal above roughly 50 nT was found out to 1 ns. The authors also quote about 30 nT from the standard error of the mean; this is a different stated sensitivity measure. For their modeled long-lived response, the susceptibility bound is of order $\chi_v>-0.1$. It is not a bound on an arbitrary picosecond waveform: metallic shielding strongly filters short responses, and the detector has an approximately 160 ps response scale. A simulated short-lived response produces only about 2 nT, below detection. The model compares susceptibility statistics from six reference pellets rather than measuring the driven susceptibility of six samples. The authors conclude that these measurements do not decide whether Meissner diamagnetism is present or absent. [R11](#ref-source-e7138d083320dfd7)

Compare the observable, the clock and the uncertainty before combining these experiments.

| Experiment and observable | Protocol or time scale | Interpretation boundary |
|---|---|---|
| Budden optical extrapolation [R5](#ref-source-07be806c0002c690) | 100 K; 200 ps pump in Figure 4 | Zero-frequency resistivity is fitted; bars are fit confidence intervals |
| Budden electrical transport [R5](#ref-source-07be806c0002c690) | 100 K; 75 ps pump and 1 ns voltage probe | Two-terminal result with static contact calibration; shaded systematic error remains |
| Adelinia film voltage [R10](#ref-source-930b28b64275da42) | Quasi-DC bias and ultrafast switches | Granular film interpretation does not transfer unchanged to pressed powder |
| Fava magnetic response [R9](#ref-source-65e69ec93039deb9) | 100 / 300 K; approximately 1 ps signal | GaP edge-field signal and geometry-dependent susceptibility; no persistent equilibrium transition |
| De Vecchi magnetic limit [R11](#ref-source-e7138d083320dfd7) | 50 K; about 160 ps detector response; window to 1 ns | Sensitivity and metal shielding constrain the null result; short and long-lived models differ |

## Limits and disputes

Dodge and colleagues argue that saturation-dependent excitation depth can create misleading superconducting-like reconstructed spectra. Buzzi and colleagues' March 2023 preprint response disputes that interpretation, arguing that the inductive signature survives their alternative reconstructions. The local profile and Drude checks above do not resolve this dispute. Compare raw reflected fields, depth assumptions, spectral bandwidth and independent transport or magnetic evidence rather than treating a fitted gap as a unique diagnosis. [R7](#ref-source-a85b56be7c62bf11) [R8](#ref-source-56a2c1fa63bafe80)

Long-lived after a short pulse does not mean thermodynamic equilibrium. Quantify absorbed energy, depth gradients, carrier and lattice temperatures, relaxation and repetition-rate heating. Selective excitation of a phonon does not establish that equilibrium pairing is phonon-mediated. Report the detector and circuit response alongside the pump duration: a 1 ps drive does not give every probe 1 ps resolution. A null magnetic result constrains the response only through the measured sensitivity and the assumed geometry and time dependence. Optical, contact-calibrated electrical and magnetic observations should retain their own uncertainty models. The present review covers selected original passages and figures; full supplements, remaining version comparisons, experimental raw-data reproduction and complete scientific acceptance remain open. [R3](#ref-source-b47831832e13ca4e) [R5](#ref-source-07be806c0002c690) [R6](#ref-source-30e68110da17974c) [R10](#ref-source-930b28b64275da42) [R11](#ref-source-e7138d083320dfd7)

## Discovery implications

Use synchronized optical, electrical and magnetic probes with explicit controls and uncertainty. Report signal duration separately from formation time and instrumental resolution. Keep equilibrium transition records separate from driven base temperatures and model estimates in databases and search filters. Theory should predict observables under the actual drive protocol, including relaxation, rather than equating an attractive model interaction with an experimentally established superconducting phase. [R5](#ref-source-07be806c0002c690) [R6](#ref-source-30e68110da17974c) [R9](#ref-source-65e69ec93039deb9) [R11](#ref-source-e7138d083320dfd7)

## Related topics

Compare [fullerides](/scwiki/fulleride-superconductors), [electrostatic gating](/scwiki/electrostatic-gating), [magnetic fields](/scwiki/magnetic-field), [pair-density waves](/scwiki/pair-density-wave) and [critical fields](/scwiki/critical-fields).

## Material cases

Values describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.

| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |
|---|---|---|---|---|---|---|
| La1.675Eu0.2Sr0.125CuO4 (aliases: LESCO, cuprate, cuprates); Fausti stripe-ordered specimen,5ps spectrum | 10 K; Base temperature for driven optical response, not an equilibrium transition. | transient-response; transient-optical-coherence | THz c-axis reflectance | ambient; unknown GPa | transient | experiment; [source](#ref-source-c60f0131e7d25c60) |
| YBa2Cu3O6.5 (aliases: YBCO, cuprate, cuprates); Hu equilibrium reference | 50 K; Approximate equilibriumTc; precise operational transition criterion not independently checked. | transition; transition-unspecified | Equilibrium reference in optical study | ambient; unknown GPa | equilibrium | experiment; [source](#ref-source-e8775e639989b8d6) |
| YBa2Cu3O6.5 (aliases: YBCO, cuprate, cuprates); Hu narrowband driven measurement | 300 K; Room-temperature driven response is not a300K equilibriumTc. | transient-response; transient-interlayer-optical-response | Narrowband THz optics | ambient; unknown GPa | transient | experiment; [source](#ref-source-e8775e639989b8d6) |
| K3C60 (aliases: fulleride, fullerides); Mitrano equilibrium reference | 20 K; Approximate equilibrium transition; not the optical-gap energy or a driven measurement temperature. | transition; transition-unspecified | Equilibrium optical comparison | ambient; unknown GPa | equilibrium | experiment; [source](#ref-source-6ee3670220e24ff1) |
| K3C60 (aliases: fulleride, fullerides); Budden extended-pulse experiment | 100 K; Driven base temperature; contact-calibrated resistance compatible with zero does not establish equilibriumTc100K. | transient-response; calibrated-transient-two-terminal-resistance | Electrical transport and optical comparison | ambient; unknown GPa | transient | experiment; [source](#ref-source-07be806c0002c690) |
| K3C60 (aliases: fulleride, fullerides); Adelinia25K granular-film voltage response | 25 K; Model-dependent granular interpretation; base temperature notTc. | transient-response; time-resolved-voltage-response | Photoconductive-switch voltmeter | ambient; unknown GPa | transient | experiment; [source](#ref-source-930b28b64275da42) |
| K3C60 (aliases: fulleride, fullerides); Adelinia100K linear positive voltage response | 100 K; Above80K sign reversal;100Kpositive response linear over measured currents, not a transition. | measurement; linear-positive-photovoltage | Photoconductive-switch voltmeter | ambient; unknown GPa | transient | experiment; [source](#ref-source-930b28b64275da42) |
| YBa2Cu3O6.48 (aliases: YBCO, cuprate, cuprates); Fava magnetic-response measurement | 100 K; Approximately1ps response with geometry-dependent susceptibility estimate; not equilibriumTc. | transient-response; transient-magnetic-field-expulsion | Faraday rotation in nearby GaP | ambient; unknown GPa | transient | experiment; [source](#ref-source-65e69ec93039deb9) |
| YBa2Cu3O6.48 (aliases: YBCO, cuprate, cuprates); Fava room-temperature magnetic response | 300 K; Driven300K base temperature with approximately1ps signal, not a persistent equilibrium Meissner transition. | transient-response; transient-magnetic-field-expulsion | Faraday rotation in nearby GaP | ambient; unknown GPa | transient | experiment; [source](#ref-source-65e69ec93039deb9) |
| K3C60 (aliases: De Vecchi magnetic limit, fulleride, fullerides); De Vecchi driven magnetic null-result protocol | 50 K; Base temperature for the driven magnetic measurement. No transition assigned; the sensitivity-limited null result does not establish absence of every transient diamagnetic waveform. | measurement; sensitivity-limited-magnetic-nonobservation | Faraday magnetometry in Bi:LIGG with finite detector and metallic-shielding response | ambient; unknown GPa | transient | experiment; [source](#ref-source-e7138d083320dfd7) |

## Sources

### Ref source-c60f0131e7d25c60

[R1] Light-Induced Superconductivity in a Stripe-Ordered Cuprate (2011). [DOI 10.1126/science.1197294](https://doi.org/10.1126/science.1197294). Publication: journal-article. Check: selected-final-optical-protocol-and-figures. Checked: 2026-10-18. Published 14 January 2011. Selected journal pp.189–191 read; PDF p.3 Figures2–3 visually checked. Caption16micrometres versus main15micrometres retained by protocol. Probe depth is10micrometres, not text-extraction mm. Measured100ps window is not a measured nanosecond lifetime. Full supplement and rawdata not reviewed.
### Ref source-e8775e639989b8d6

[R2] Optically enhanced coherent transport in YBa2Cu3O6.5 by ultrafast redistribution of interlayer coupling (2014). [DOI 10.1038/nmat3963](https://doi.org/10.1038/nmat3963). Publication: journal-article. Check: selected-author-optical-and-effective-medium-passages. Checked: 2026-10-18. Selected author manuscript pp.1–7 read:50K equilibrium reference, pump parameters, transformed fraction, screened/unscreened frequencies and broadband/narrowband comparison. Downloaded current author version; complete version history, final comparison, supplement and inversion reproduction not checked.
### Ref source-b47831832e13ca4e

[R3] Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5 (2014). [DOI 10.1038/nature13875](https://doi.org/10.1038/nature13875). Publication: journal-article. Check: selected-author-introduction-only. Checked: 2026-10-18. Author v1 initial pp.1–2 selected introduction: diffraction and density-functional structural interpretation. Early title differs from published title. Detailed refinement, supplementary methods and final-version comparison not reviewed.
### Ref source-6ee3670220e24ff1

[R4] Possible light-induced superconductivity in K3C60 at high temperature (2016). [DOI 10.1038/nature16522](https://doi.org/10.1038/nature16522). Publication: journal-article. Check: selected-final-optical-interpretation. Checked: 2026-10-19. Online8February2016,issue25February. Selected final p.461 main text, equilibrium20K reference and model-dependent optical-gap interpretation read. Full methods, extended data and rawdata not reanalyzed; no direct DC/Meissner result inferred. Publisher correction notice dated 24 February 2016 identifies a restored final sentence in the advance-online PDF Figure 4 caption; no full old/corrected PDF comparison was performed.
### Ref source-07be806c0002c690

[R5] Evidence for metastable photo-induced superconductivity in K3C60 (2021). [DOI 10.1038/s41567-020-01148-1](https://doi.org/10.1038/s41567-020-01148-1). Publication: journal-article. Check: selected-final-transport-probe-and-uncertainty-comparison. Checked: 2026-10-20. M. Budden et al.; online4February2021,issueMay. Selected p.611 and p.615 Fig4/caption and transport discussion read, p.615 visually checked. Static four-terminal contact calibration is distinct from transient two-terminal transport.200ps/75ps pumps and100K base retained; complete supplement/rawdata not reviewed. Follow-up visually checks p.615: 1 ns voltage probe; optical fit confidence bars versus transport contact-calibration systematic shading. These are not interchangeable uncertainties.
### Ref source-30e68110da17974c

[R6] Transient superconductivity from electronic squeezing of optically pumped phonons (2017). [DOI 10.1038/nphys4024](https://doi.org/10.1038/nphys4024). Publication: journal-article. Check: selected-author-oscillator-equations. Checked: 2026-10-18. Author v1 dated13September2016; journal online30January2017. Selected pp.2–4 Hamiltonian, occupation-dependent oscillator and approximate effective model read; p.3 Eq2 visually checked. hbar restored explicitly. Full time-dependent numerics, supplement and final comparison remain open.
### Ref source-a85b56be7c62bf11

[R7] Optical Saturation Produces Spurious Evidence for Photoinduced Superconductivity in K3C60 (2023). [DOI 10.1103/PhysRevLett.130.146002](https://doi.org/10.1103/PhysRevLett.130.146002). Publication: journal-article. Check: selected-final-depth-profile-equations. Checked: 2026-10-18. Published3April2023. Author-hosted file has final PRL layout: selected pp.1–2 and Eq3–4 read; p.2 visually checked. Saturation integral independently evaluated. Full Maxwell inversion, remaining figures and rawdata reanalysis not reproduced.
### Ref source-56a2c1fa63bafe80

[R8] Comment on arXiv:2210.01114: Optical Saturation Produces Spurious Evidence for Photoinduced Superconductivity in K3C60 (2023). [DOI 10.48550/arXiv.2303.10169](https://doi.org/10.48550/arXiv.2303.10169). Publication: preprint. Check: selected-preprint-response. Checked: 2026-10-20. Preprint submitted17March2023. Selected pp.1–2 response read: authors dispute the depth-profile critique and emphasize retained inductive behavior. Figure reconstruction and experimental rawdata not independently reproduced; no journal publication established here. arXiv record rechecked: only v1 is listed, without a journal reference. This does not independently establish that no later journal work exists.
### Ref source-65e69ec93039deb9

[R9] Magnetic field expulsion in optically driven YBa2Cu3O6.48 (2024). [DOI 10.1038/s41586-024-07635-2](https://doi.org/10.1038/s41586-024-07635-2). Publication: journal-article. Check: selected-journal-formatted-author-copy. Checked: 2026-10-18. Publisher dates:online10July2024,issue1August. Author-hosted journal-formatted copy still has placeholder publication date; selected pp.1,4 magnetic-methods/results read. GaP,100/300K,~1ps and quasi-static caveat retained. Complete final-version comparison, calibration, full supplement and simulations remain open.
### Ref source-930b28b64275da42

[R10] Probing optically driven K3C60 thin films with an ultrafast voltmeter (2025). [DOI 10.1063/4.0000295](https://doi.org/10.1063/4.0000295). Publication: journal-article. Check: selected-final-voltage-protocol-and-temperature-response. Checked: 2026-10-18. Published26March2025. Selected journal pp.1–3 and original abstract/figure captions read. QuasiDC bias,300fs/7micrometre pump,sign reversal80K and100K linear positive response retained. Full granular model, circuit calibration and supplement not reproduced.
### Ref source-e7138d083320dfd7

[R11] Upper limit on magnetic field expulsion in optically driven K3C60 (2025). [DOI 10.1103/21g5-x5bj](https://doi.org/10.1103/21g5-x5bj). Publication: journal-article. Check: selected-final-null-protocol-detector-and-model-limit. Checked: 2026-10-20. Selected final pp.3–6 read; Figure 3 on p.4 and Appendix A/B calibration-response passages on p.6 visually checked. 50 K, 40 mJ/cm², 0.5 mT and the 1 ns window retained. Approximately 160 ps detector response and metal shielding distinguish short-waveform predictions from long-lived susceptibility limits. Six reference pellets provide model comparison statistics. Full Maxwell, raw-data and remaining appendices/supplement review remain open.

## Claim evidence and conditions

### scwiki-e6-claim-scope-1

Light can change carrier populations, excite lattice motion and alter collective electronic response. Persistent photodoping, a transient pump–probe state and a periodically driven model are different protocols. Specify wavelength, polarization, pulse duration, fluence, repetition rate, base temperature and probe delay. A temperature at which a driven response is observed is not automatically an equilibrium superconducting transition temperature.

Evidence: experiment. Sources: source-c60f0131e7d25c60, source-e8775e639989b8d6, source-6ee3670220e24ff1, source-30e68110da17974c.

Source relationship: context-for-editorial-analysis. Editorial synthesis retains distinctions among model mechanisms, protocols and measured observables; no universal transition is inferred.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-scope-2

The evidence now extends beyond optical conductivity. Electrical measurements in K3C60, transient magnetic measurements in YBa2Cu3O6.48 and a later sensitivity-limited magnetic experiment on K3C60 ask different questions. Preserve the specimen, geometry and measured observable rather than combining them into one universal light-induced transition.

Evidence: experiment. Sources: source-07be806c0002c690, source-65e69ec93039deb9, source-930b28b64275da42, source-e7138d083320dfd7.

Source relationship: context-for-editorial-analysis. Editorial synthesis retains distinctions among model mechanisms, protocols and measured observables; no universal transition is inferred.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-mathematical-assumptions-1

With the $e^{-i\omega t}$ convention, a normal Drude response is $\sigma(\omega)=D/(\Gamma-i\omega)$, where $D$ is the Drude weight and $\Gamma>0$ the relaxation rate. Thus $\sigma_2=D\omega/(\Gamma^2+\omega^2)\approx D/\omega$ when the measured frequencies greatly exceed $\Gamma$, although the DC conductivity $D/\Gamma$ remains finite. A finite-band inductive trend alone cannot distinguish this limit from a condensate. This elementary counterexample is not a fit to, or refutation of, any particular experiment.

Evidence: theory. Sources: source-6ee3670220e24ff1, source-a85b56be7c62bf11.

Source relationship: context-for-local-derivation. The local mathematical examples illustrate conditional models, not fits to an experiment or resolution of the reconstruction dispute.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-mathematical-assumptions-2

Depth reconstruction also matters. For Dodge's illustrative saturating profile, $\Delta\sigma(z)=\Delta\sigma_{\rm sat}f e^{-z/\Lambda}/(1+f e^{-z/\Lambda})$, with $f=F/F_{\rm sat}$, integration gives sheet photoconductance $\Delta G=\Delta\sigma_{\rm sat}\Lambda\ln(1+f)$. The effective thickness grows with fluence even while the surface response saturates. Assuming a fixed exponential profile can therefore bias the inferred surface conductivity. This integral checks the stated profile, not a full electromagnetic inversion; the experimental interpretation is disputed below.

Evidence: theory. Sources: source-a85b56be7c62bf11, source-56a2c1fa63bafe80.

Source relationship: context-for-local-derivation. The local mathematical examples illustrate conditional models, not fits to an experiment or resolution of the reconstruction dispute.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-mathematical-assumptions-3

Kennes's minimal quadratic electron–phonon model gives oscillator frequency $\omega(n)=\omega_0\sqrt{1+2gn}$ for site occupation $n=0,1,2$, requiring $g>-1/4$. At fixed phonon occupation $n_B$, its induced interaction is $\Delta U=(n_B+1/2)\hbar\omega_0[\sqrt{1+4g}+1-2\sqrt{1+2g}]$. Concavity makes this nonpositive for either sign of stable $g$, with leading term $-(n_B+1/2)\hbar\omega_0g^2$. The author manuscript sets Planck's constant to one; it is restored here. This is a model mechanism, not a measured coupling or proof of a stable superconducting phase.

Evidence: theory. Sources: source-30e68110da17974c.

Source relationship: context-for-local-derivation. The local mathematical examples illustrate conditional models, not fits to an experiment or resolution of the reconstruction dispute.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-1

Fausti studied stripe-ordered La1.675Eu0.2Sr0.125CuO4 at a 10 K base temperature. The reported signal is a transient c-axis plasma edge and optical response interpreted as restored interlayer coherence. Figures 2–3 specify a 16 micrometre pump, approximately 1 mJ/cm² fluence and a 5 ps delay for the transient spectrum. The pump excites roughly 200 nm in depth, while the THz probe samples about 10 micrometres; the transformed-layer reconstruction is essential. A near-infrared plateau observed to 100 ps does not directly measure a many-nanosecond lifetime.

Evidence: experiment. Sources: source-c60f0131e7d25c60.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-2

Hu's YBa2Cu3O6.5 specimen has an equilibrium transition near 50 K. Its approximately 300 fs, 15 micrometre pump modifies both inter- and intra-bilayer optical response. The effective-medium analysis separates transformed and untransformed regions; screened plasma-edge positions are not the same as fitted unscreened plasma frequencies. Broadband data at 60 K and narrower-band measurements at 100 and 300 K have different information content. Mankowsky's associated structural study combines diffraction with calculations to connect driven distortions with electronic changes; structural response does not uniquely identify pairing.

Evidence: experiment. Sources: source-e8775e639989b8d6, source-b47831832e13ca4e.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-3

Mitrano's K3C60 report compares a transient optical response above the roughly 20 K equilibrium transition with the low-temperature spectrum. Its title deliberately says “Possible”. The reported optical-gap fit and enhanced carrier mobility are not a direct DC resistance or magnetic measurement. Temperature, pump–probe delay and model-dependent gap extraction must remain attached to that evidence.

Evidence: experiment. Sources: source-6ee3670220e24ff1.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-4

Budden extended the response using longer pulses. Figure 4 compares optical extrapolation with electrical measurements at a 100 K base temperature and about 25 mJ/cm² fluence. The optical and transport pump durations are 200 ps and 75 ps, respectively; the electrical voltage probe lasts 1 ns. The electrical experiment is transient two-terminal transport with contact contributions calibrated from static four-terminal measurements; it is not a direct transient four-terminal measurement. The optical error bars describe a fit confidence interval, while the transport shading estimates contact-calibration systematic error. Those uncertainties cannot be interchanged or discarded when assessing compatibility with zero. Recovery over tens of nanoseconds supports the authors' metastable interpretation without establishing a pump-free equilibrium transition at 100 K. The drive, probe and recovery times are different quantities.

Evidence: experiment. Sources: source-07be806c0002c690.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-5

Adelinia's 2025 thin-film study uses a quasi-DC bias, 300 fs pulses at 7 micrometres and photoconductive switches to resolve voltage dynamics. Granular-film and powder results are not interchangeable. The above-transition voltage response changes sign at 80 K; at 100 K it is positive and linear across the measured current range. Fitted superfluid fractions and weak-link phase-slip dynamics depend on the granular two-fluid model. A 100 K measurement in this paper must not become a 100 K superconducting-transition record.

Evidence: experiment. Sources: source-930b28b64275da42.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-6

Fava's 2024 YBa2Cu3O6.48 experiment detects a transient magnetic-field enhancement near the excited region's edge using Faraday rotation in a nearby GaP detector. Signals at 100 and 300 K last about 1 ps. The inferred diamagnetic susceptibility of order −0.3 depends on geometry and the magnetic-response model; the paper itself cautions that a quasi-static estimate is not fully justified for this dynamics. This provides a complementary magnetic observable, while remaining distinct from a persistent equilibrium Meissner state.

Evidence: experiment. Sources: source-65e69ec93039deb9.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-experimental-criteria-7

De Vecchi's December 2025 K3C60 study used a 50 K base temperature, about 1 ps pulses at 8 micrometres, 40 mJ/cm² fluence and a 0.5 mT applied field. No statistically significant photo-induced field signal above roughly 50 nT was found out to 1 ns. The authors also quote about 30 nT from the standard error of the mean; this is a different stated sensitivity measure. For their modeled long-lived response, the susceptibility bound is of order $\chi_v>-0.1$. It is not a bound on an arbitrary picosecond waveform: metallic shielding strongly filters short responses, and the detector has an approximately 160 ps response scale. A simulated short-lived response produces only about 2 nT, below detection. The model compares susceptibility statistics from six reference pellets rather than measuring the driven susceptibility of six samples. The authors conclude that these measurements do not decide whether Meissner diamagnetism is present or absent.

Evidence: experiment. Sources: source-e7138d083320dfd7.

Source relationship: direct-support. Source-specific observations retain their drive, probe, uncertainty and interpretation limits.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-limits-and-disputes-1

Dodge and colleagues argue that saturation-dependent excitation depth can create misleading superconducting-like reconstructed spectra. Buzzi and colleagues' March 2023 preprint response disputes that interpretation, arguing that the inductive signature survives their alternative reconstructions. The local profile and Drude checks above do not resolve this dispute. Compare raw reflected fields, depth assumptions, spectral bandwidth and independent transport or magnetic evidence rather than treating a fitted gap as a unique diagnosis.

Evidence: experiment. Sources: source-a85b56be7c62bf11, source-56a2c1fa63bafe80.

Source relationship: context-for-editorial-analysis. Editorial synthesis retains distinctions among model mechanisms, protocols and measured observables; no universal transition is inferred.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-limits-and-disputes-2

Long-lived after a short pulse does not mean thermodynamic equilibrium. Quantify absorbed energy, depth gradients, carrier and lattice temperatures, relaxation and repetition-rate heating. Selective excitation of a phonon does not establish that equilibrium pairing is phonon-mediated. Report the detector and circuit response alongside the pump duration: a 1 ps drive does not give every probe 1 ps resolution. A null magnetic result constrains the response only through the measured sensitivity and the assumed geometry and time dependence. Optical, contact-calibrated electrical and magnetic observations should retain their own uncertainty models. The present review covers selected original passages and figures; full supplements, remaining version comparisons, experimental raw-data reproduction and complete scientific acceptance remain open.

Evidence: experiment. Sources: source-b47831832e13ca4e, source-07be806c0002c690, source-30e68110da17974c, source-930b28b64275da42, source-e7138d083320dfd7.

Source relationship: context-for-editorial-analysis. Editorial synthesis retains distinctions among model mechanisms, protocols and measured observables; no universal transition is inferred.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

### scwiki-e6-claim-discovery-implications-1

Use synchronized optical, electrical and magnetic probes with explicit controls and uncertainty. Report signal duration separately from formation time and instrumental resolution. Keep equilibrium transition records separate from driven base temperatures and model estimates in databases and search filters. Theory should predict observables under the actual drive protocol, including relaxation, rather than equating an attractive model interaction with an experimentally established superconducting phase.

Evidence: theory. Sources: source-07be806c0002c690, source-30e68110da17974c, source-65e69ec93039deb9, source-e7138d083320dfd7.

Source relationship: context-for-editorial-analysis. Editorial synthesis retains distinctions among model mechanisms, protocols and measured observables; no universal transition is inferred.

Conditions: Drive and probe protocols, base temperatures, sample granularity and transient versus equilibrium states remain distinct. Model assumptions and response bounds retained.

Verification scope: Selected primary passages/figures, explicit version limits and bounded algebra; full scientific acceptance remains open.

## Revision and review

Article ID: scwiki-e6. Revision: 5181b51f1acd6e320368. Updated: 2026-10-19.

Review scope: Selected original optical/transport/magnetic passages; Fausti, Budden, Dodge and Kennes figure/equation visual checks; bounded Drude, saturation-depth and oscillator calculations. Publisher notice identifying the 24 February 2016 Mitrano caption correction checked separately on 19 October 2026. Follow-up: Budden final p.615 Figure 4 and transport paragraph; De Vecchi final pp.3–6 including Figure 3 and detector calibration; selected Fava p.4, Mankowsky v1 introduction, Kennes v1 pp.3–4 and Adelinia abstract.

- Complete scientific acceptance, remaining final-version comparisons, full supplements and raw-data reproduction remain open.
- Fava author-hosted journal-formatted copy retains a placeholder date; publisher dates checked separately. Hu downloaded author-version history not fully compared.
- The Buzzi2023 response remains explicitly a preprint; local algebra does not settle the optical-reconstruction dispute.
- A model-induced attraction, driven base temperature or sensitivity-limited null signal is not a measured equilibrium superconducting transition.
- Detector response and modeled long-lived susceptibility bounds do not exclude every short waveform; no full Maxwell reconstruction, circuit calibration or raw-data refit was performed.

Source: [E_tuning_parameters/E6_light_irradiation.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/E_tuning_parameters/E6_light_irradiation.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 3da3dff0df0053d72c0d3d8c59f5b2c25badd5cb36c55fb55d3e02748472f709.