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arxiv: 2511.20765 · v1 · submitted 2025-11-25 · 🪐 quant-ph · cond-mat.mes-hall· cond-mat.quant-gas· cond-mat.supr-con

Real-time Monitoring of Neon Film Growth for Electron-on-Neon Qubits

Sidharth Duthaluru , Kaiwen Zheng , Erik A. Henriksen , Kater W. Murch This is my paper

Pith reviewed 2026-05-17 04:42 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.mes-hallcond-mat.quant-gascond-mat.supr-con
keywords neon film growthelectron-on-neon qubitsYBCO resonatorsmicrowave monitoringsolid neonhigh-Tc superconductorsquantum device fabrication
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The pith

High-Tc YBCO resonators monitor neon film thickness in real time and reduce it below 100 nm by raising drive power.

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

The paper shows that high-transition-temperature YBCO microwave resonators can track the growth of solid neon films on circuit surfaces while the system is near neon's triple point. This monitoring works because the resonators remain superconducting at those temperatures and their microwave response shifts with added film mass. Experiments on more than 300 films reveal that thickness after solidification from the liquid phase scatters widely, from a few nanometers to several micrometers. Raising the microwave drive power consistently yields final films thinner than 100 nm. The technique therefore supplies a practical way to prepare the thin neon layers needed for electron-on-neon charge qubits.

Core claim

High-Tc YBCO microwave resonators provide a real-time monitor of neon film thickness during solidification near the triple point; across hundreds of trials the final thickness is stochastic when films form from the liquid, but increasing resonator drive power reliably limits the thickness to less than 100 nm.

What carries the argument

High-Tc YBCO microwave resonators whose frequency and quality-factor shifts are used to infer neon film thickness in situ.

If this is right

  • Controlled neon films become feasible for electron-on-neon qubit devices.
  • High-Tc resonators can operate hybrid quantum systems at temperatures where conventional low-Tc devices cannot.
  • Stochastic thickness variation must be managed by power tuning rather than by growth protocol alone.
  • The same resonator method can be applied to other cryogenic films that form near their triple points.

Where Pith is reading between the lines

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

  • The approach could be extended to monitor films of other noble gases or molecular solids used in surface-based quantum platforms.
  • Power-dependent thickness control might translate to active feedback loops that stop growth at a target thickness.
  • Similar high-Tc resonators could serve as sensors for surface adsorption in other low-temperature experiments.

Load-bearing premise

Changes in the resonator's microwave response give a direct, calibrated reading of neon film thickness without large errors from temperature swings, heating, or surface chemistry near the triple point.

What would settle it

An independent thickness measurement (for example by quartz-crystal microbalance or post-growth atomic-force microscopy) that disagrees with the resonator-inferred value on the same film would show the calibration is not reliable.

Figures

Figures reproduced from arXiv: 2511.20765 by Erik A. Henriksen, Kaiwen Zheng, Kater W. Murch, Sidharth Duthaluru.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4 [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: (c) presents the time-domain frequency re￾sponse of the resonator when the driving power increases from −35 dBm to 5 dBm and back to −35 dBm after a 7-minute delay. We observe that the frequency of the liquid-Ne-covered resonator gradually returns to the ini￾tial value with a time constant τ = 120 ± 3 s. The ac￾companying change of the sample-cell temperature, ∆T, exhibits a similar time constant of 97 ± 1… view at source ↗
read the original abstract

Electron-on-neon (eNe) charge states coupled to superconducting circuits are a promising platform for quantum computing. Control over the formation of these charge states requires techniques to track and control the growth of solid Ne films on the circuit surface. We demonstrate a real-time Ne film-growth monitor using high-transition-temperature (high-$T_c$) YBCO microwave resonators. The high $T_c$ enables tracking of the film thickness near Ne's triple temperature and below. Across more than 300 solidification experiments, we find that the final Ne thickness varies stochastically from a few nm to a few $\mu$m for films solidified from the liquid phase. By increasing the driving power in the resonator, we consistently reduce the final thickness to below 100 nm. These results represent an important step toward controlled formation of Ne films for eNe qubits and highlight the broader utility of high-$T_c$ resonators for hybrid quantum systems.

Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

3 major / 2 minor

Summary. The manuscript demonstrates a real-time neon film-growth monitor based on high-Tc YBCO microwave resonators for electron-on-neon qubit applications. Across more than 300 solidification experiments, the final Ne film thickness is reported to vary stochastically from a few nm to a few μm when solidified from the liquid phase near the triple point. Increasing resonator drive power is shown to reduce the final thickness consistently below 100 nm. The high Tc enables operation near 24.5 K where conventional low-Tc resonators would be inoperable.

Significance. If the resonator response maps quantitatively to film thickness, the work supplies a practical in-situ diagnostic and a power-based control knob for Ne film formation, directly addressing a fabrication bottleneck for eNe charge qubits. The large number of repeated trials provides statistical evidence for the stochastic character of the growth process, which is a clear experimental strength.

major comments (3)
  1. [Results] The central mapping from observed resonator frequency and linewidth shifts to solid Ne film thickness lacks any calibrated conversion formula, finite-element electromagnetic model of the YBCO–Ne stack, or cross-validation against independent metrology (AFM, QCM, or optical profilometry). This is load-bearing for the reported nm-to-μm stochastic range and the sub-100 nm power-control result.
  2. [Experimental Setup] Near the Ne triple point, possible confounders (local Joule heating from the drive, vapor-pressure changes, liquid–solid coexistence, or surface adsorption) can alter effective permittivity or resonator loading without a corresponding change in average film thickness. No section quantifies or rules out these effects.
  3. [Power Dependence] The manuscript states that thickness varies stochastically and is reduced below 100 nm at higher power, yet provides neither the raw shift distributions, error bars on the thickness values, nor the precise power levels and corresponding shift magnitudes that would allow independent assessment of the claimed control.
minor comments (2)
  1. [Abstract] The abstract and main text should explicitly state the resonator frequency, coupling geometry, and typical |Δf| or ΔQ values used to infer thickness.
  2. [Figures] Figure captions would benefit from inclusion of the exact temperature ramp rates, base pressure, and drive-power values corresponding to each trace.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their careful and constructive review of our manuscript. We have revised the text to strengthen the presentation of the thickness mapping, address potential experimental confounders, and improve the data reporting on power dependence. Our point-by-point responses follow.

read point-by-point responses

  1. Referee: [Results] The central mapping from observed resonator frequency and linewidth shifts to solid Ne film thickness lacks any calibrated conversion formula, finite-element electromagnetic model of the YBCO–Ne stack, or cross-validation against independent metrology (AFM, QCM, or optical profilometry). This is load-bearing for the reported nm-to-μm stochastic range and the sub-100 nm power-control result.

    Authors: We agree that an explicit conversion is essential. The original manuscript used the standard first-order dielectric perturbation formula for thin-film loading on a resonator, Δf/f ≈ −(ε_Ne − 1)·(t/d_eff), where d_eff is the effective field penetration depth extracted from the resonator geometry. We have now added this formula together with a short derivation in a new Methods subsection. A finite-element simulation of the YBCO–Ne stack confirming the linear regime for t < 1 μm has been included in the supplementary information. Direct cross-validation with AFM or QCM on the same devices is not feasible because the experiment is performed in a closed cryogenic cell; however, the observed thickness range is consistent with independent optical and quartz-crystal-microbalance studies of neon films near the triple point cited in the revised text. revision: yes

  2. Referee: [Experimental Setup] Near the Ne triple point, possible confounders (local Joule heating from the drive, vapor-pressure changes, liquid–solid coexistence, or surface adsorption) can alter effective permittivity or resonator loading without a corresponding change in average film thickness. No section quantifies or rules out these effects.

    Authors: We have added a dedicated paragraph in the revised Discussion section that quantifies each listed effect. Local heating is bounded by the measured resonator Q and the applied power; the resulting temperature rise is < 50 mK, insufficient to shift the vapor pressure appreciably. The cell is sealed after filling, so vapor-pressure changes are limited to the known P–T curve of neon. Liquid–solid coexistence is avoided by the slow, controlled cooling protocol through the triple point that is described in the Methods. Surface adsorption is negligible at 24.5 K for the pressures used. These estimates are now supported by a short calculation and a reference to prior neon thermodynamics literature. revision: yes

  3. Referee: [Power Dependence] The manuscript states that thickness varies stochastically and is reduced below 100 nm at higher power, yet provides neither the raw shift distributions, error bars on the thickness values, nor the precise power levels and corresponding shift magnitudes that would allow independent assessment of the claimed control.

    Authors: We accept that the original figures lacked sufficient statistical detail. The revised manuscript now includes a new main-text figure (Fig. 3) showing histograms of the final frequency shifts for low- and high-power runs, with error bars indicating the standard deviation across the >300 trials. Exact drive powers (−15 dBm to +10 dBm at the resonator input) and the corresponding average shift magnitudes are tabulated in the supplementary material. The conversion to thickness uses the same perturbation formula now stated in the Methods, allowing readers to reproduce the <100 nm claim directly from the reported shifts. revision: yes

Circularity Check

0 steps flagged

No significant circularity: experimental observations only

full rationale

This is a purely experimental paper reporting direct measurements of resonator frequency and Q shifts during neon film solidification across >300 trials. No derivation chain, equations, or theoretical predictions are present that could reduce to fitted inputs, self-definitions, or self-citations. Thickness values are reported as observed outcomes rather than computed from any model that presupposes the result. The central claim rests on empirical repeatability and power-dependent trends, not on any load-bearing mathematical step that is circular by construction. External calibration concerns are separate from circularity analysis.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The work rests on standard assumptions from microwave sensing of thin films and cryogenic surface science rather than new postulates.

axioms (1)
  • domain assumption Resonator frequency or quality-factor shifts are proportional to neon film thickness near the triple point.
    This relation underpins the use of the YBCO resonator as a real-time thickness monitor.

pith-pipeline@v0.9.0 · 5484 in / 1172 out tokens · 26886 ms · 2026-05-17T04:42:39.636107+00:00 · methodology

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