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A single electron on solid neon forms a charge qubit with coherent microwave control at Rabi frequencies up to 76 MHz.

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2026-07-02 22:54 UTC pith:OMUXFSZP

load-bearing objection The 76 MHz Rabi frequency and NbTiN resonator are the clear new pieces; the single-electron claim rests on differential coupling without direct charge counting. the 1 major comments →

arxiv 2605.31185 v2 pith:OMUXFSZP submitted 2026-05-29 cond-mat.mes-hall quant-ph

Fast coherent control of a charge qubit on solid neon with a spin-qubit-compatible resonator

Jun Wang , Yiran Tian , Ivan Grytsenko , Asher Jennings , Beatriz P\'erez Gonz\'alez , Xianjing Zhou , Hirotaka Terai , Dafei Jin
show 2 more authors
Monica Benito Erika Kawakami
This is my paper
classification cond-mat.mes-hall quant-ph
keywords charge qubitsolid neonsuperconducting resonatorcoherent controlRabi frequencymicrowave readoutelectron qubitspin qubit
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.

The paper demonstrates coupling of an electron on solid neon to a NbTiN nanowire resonator compatible with magnetic fields. Microwave signals enable both readout of the charge state and coherent driving of the qubit. Rabi frequencies reach 76 MHz, an order of magnitude above prior work on similar platforms. The results support progress toward spin qubits with potentially long coherence times, even though the electron position is inferred rather than placed deterministically.

Core claim

We couple a single electron on solid neon to a magnetic-field-compatible superconducting NbTiN nanowire resonator. We realize a charge qubit and demonstrate microwave readout and coherent control, with Rabi frequencies up to 76 MHz, an order of magnitude larger than in previous studies. Under strong driving, we observe a qubit frequency shift from nonlinear interactions with the intense microwave field. Deterministic electron trapping at an intended position remains challenging due to solid neon surface roughness; we characterize the electron's position from its differential coupling to distinct electrodes. Although not trapped at an intended position, our estimates indicate that spin-qubit

What carries the argument

The charge qubit formed by the two possible positions of a single electron on the neon surface, whose state is read out and driven through coupling to the NbTiN superconducting resonator.

Load-bearing premise

The microwave signals arise from a single electron whose position can be reliably inferred from differential electrode coupling despite surface roughness.

What would settle it

A direct position measurement or multi-electron signature that contradicts the inferred single-electron location while still producing the reported Rabi oscillations at 76 MHz.

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

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If this is right

  • Microwave readout becomes available for the electron charge state on solid neon.
  • Coherent control reaches Rabi frequencies of 76 MHz, supporting faster operations.
  • Nonlinear frequency shifts occur under strong microwave driving.
  • Estimates show spin-qubit demonstrations on this platform remain feasible.

Where Pith is reading between the lines

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

  • The same resonator architecture could support combined charge and spin control in one device.
  • Surface preparation methods might be tested to achieve deterministic single-electron placement.
  • Coupling the charge degree of freedom to spin could create hybrid qubits with tunable properties.
  • Multi-electron versions of the platform could explore interactions without material defects.

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 / 0 minor

Summary. The manuscript reports coupling a single electron on solid neon to a magnetic-field-compatible NbTiN nanowire resonator to realize a charge qubit. It demonstrates microwave readout and coherent control with Rabi frequencies reaching 76 MHz (an order of magnitude above prior work), observes a nonlinear qubit frequency shift under strong driving, and characterizes the electron position via differential electrode coupling despite challenges with deterministic trapping due to surface roughness. The authors conclude that spin-qubit demonstrations remain feasible based on their estimates.

Significance. If the single-electron assignment and position characterization hold, the work represents a meaningful advance for the solid-neon electron platform by delivering substantially faster coherent control and resonator compatibility with spin-qubit requirements. The nonlinear shift observation under strong driving is a notable experimental detail. The platform's isolation from material defects and potential for long coherence times would be strengthened by these results.

major comments (1)
  1. The headline claim of a single-electron charge qubit with quantified Rabi frequency and nonlinear shift rests on the resonator response arising from exactly one electron whose location is sufficiently known. The text states that deterministic trapping fails due to surface roughness and that position is inferred only from differential coupling to distinct electrodes. No independent charge-counting observable (e.g., discrete frequency jumps upon sequential loading) is described to exclude multi-electron configurations or a single electron in an unintended local minimum. This is load-bearing for interpreting the reported 76 MHz Rabi frequency and other extracted parameters as single-qubit properties. (See the sections on electron trapping, position characterization, and experimental results.)

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for identifying the key issue of single-electron assignment. We respond to the major comment below and indicate where revisions will be made.

read point-by-point responses

  1. Referee: The headline claim of a single-electron charge qubit with quantified Rabi frequency and nonlinear shift rests on the resonator response arising from exactly one electron whose location is sufficiently known. The text states that deterministic trapping fails due to surface roughness and that position is inferred only from differential coupling to distinct electrodes. No independent charge-counting observable (e.g., discrete frequency jumps upon sequential loading) is described to exclude multi-electron configurations or a single electron in an unintended local minimum. This is load-bearing for interpreting the reported 76 MHz Rabi frequency and other extracted parameters as single-qubit properties. (See the sections on electron trapping, position characterization, and experimental results.)

    Authors: We agree that confirming single-electron occupancy is central to the claims. The manuscript infers single-electron trapping from the magnitude of the resonator frequency shift upon loading, which matches the expected capacitive shift for one electron, combined with the measured differential coupling to the two electrodes that constrains the position to a local minimum. The observed Rabi oscillations up to 76 MHz and the nonlinear frequency shift under strong driving are characteristic signatures of a driven two-level system; multi-electron states would be expected to produce additional spectral features or altered coupling strengths not seen in the data. We acknowledge that an independent charge-counting method such as discrete jumps during sequential loading is absent, as the surface roughness precludes deterministic sequential trapping. In the revised manuscript we will expand the discussion of electron trapping and position characterization to explicitly address possible multi-electron interpretations and explain why the observed parameters remain most consistent with a single electron. revision: partial

Circularity Check

0 steps flagged

No circularity: purely experimental measurements with no derivation chain

full rationale

The manuscript reports experimental realization of a charge qubit on solid neon, including microwave readout, coherent control with Rabi frequencies up to 76 MHz, and observation of nonlinear frequency shifts. Position is inferred from differential electrode coupling, but this is a direct measurement characterization rather than a fitted prediction or self-referential derivation. No equations, ansatzes, uniqueness theorems, or self-citations are invoked to derive results from inputs by construction. The work is self-contained against external benchmarks (measured Rabi rates, resonator responses) and contains no load-bearing theoretical steps that reduce to the paper's own fitted values or prior self-citations.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The work is an experimental demonstration; the abstract introduces no free parameters, mathematical axioms, or new postulated entities. All claims rest on measured signals whose interpretation depends on standard assumptions about single-electron trapping and resonator coupling.

pith-pipeline@v0.9.1-grok · 5716 in / 1061 out tokens · 26740 ms · 2026-07-02T22:54:09.893894+00:00 · methodology

0 comments
Cite this review

Pith. "Pith review of Fast coherent control of a charge qubit on solid neon with a spin-qubit-compatible resonator." pith.science (2026). https://pith.science/paper/OMUXFSZP

@misc{pith2026260531185,
  author       = {Pith},
  title        = {Pith review of: Fast coherent control of a charge qubit on solid neon with a spin-qubit-compatible resonator},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/OMUXFSZP}},
  note         = {Machine review of arXiv:2605.31185}
}
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read the original abstract

Electrons floating in vacuum provide a clean platform for quantum information processing owing to their isolation from material defects. In particular, electrons on solid neon have emerged as a promising qubit platform because of their potentially long coherence times. Here, toward spin-qubit realization, we couple a single electron on solid neon to a magnetic-field-compatible superconducting NbTiN nanowire resonator. We realize a charge qubit and demonstrate microwave readout and coherent control, with Rabi frequencies up to 76 MHz, an order of magnitude larger than in previous studies. Under strong driving, we observe a qubit frequency shift from nonlinear interactions with the intense microwave field. Deterministic electron trapping at an intended position remains challenging due to solid neon surface roughness; we characterize the electron's position from its differential coupling to distinct electrodes. Although not trapped at an intended position, our estimates indicate that spin-qubit demonstrations remain feasible.

Figures

Figures reproduced from arXiv: 2605.31185 by Asher Jennings, Beatriz P\'erez Gonz\'alez, Dafei Jin, Erika Kawakami, Hirotaka Terai, Ivan Grytsenko, Jun Wang, Monica Benito, Xianjing Zhou, Yiran Tian.

Figure 1
Figure 1. Figure 1: FIG. 1. (A) Optical micrograph of the NbTiN nanowire resonator (false-color pink). The resonator is capacitively and [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. (A) Schematic of the Rabi measurement sequence. [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (A) Schematic of the Ramsey measurement sequence. [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Strong drive regime. The pulse sequence used here [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. (A) Hahn-echo measurement. The decay is fitted [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. (A) Schematic of the device geometry including the [PITH_FULL_IMAGE:figures/full_fig_p007_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. (A) Schematic illustration of an isotropic bump on [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8. (A) Device layout. The resonator center conductor is [PITH_FULL_IMAGE:figures/full_fig_p009_8.png] view at source ↗

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Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Deterministic single-electron trapping on solid neon using engineered dielectric surface geometry

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    Engineering a smooth dielectric layer with shallow etched wells can create deterministic single-electron traps on solid neon while keeping the qubit orbital splitting near the experimental value, per Schrödinger–Poiss...

Reference graph

Works this paper leans on

44 extracted references · 44 canonical work pages · cited by 1 Pith paper · 1 internal anchor

  1. [1]

    In the rotating frame of the driving frequency ωd, the Hamiltonian is given by [40]: H = ( ωr − ωd)a†a + 1 2 ( ωq − ωd + g2(2a†a + 1) ∆qr ) σz + εd(a† + a) + gεd ∆qr σx

    Dispersive coupling In the dispersive regime, i.e., g ≪ ∆qr with ∆qr = ωq − ωr being the qubit–resonator detuning, the interac- tion can be treated perturbatively. In the rotating frame of the driving frequency ωd, the Hamiltonian is given by [40]: H = ( ωr − ωd)a†a + 1 2 ( ωq − ωd + g2(2a†a + 1) ∆qr ) σz + εd(a† + a) + gεd ∆qr σx. (17) The term 2g2a†a/∆q...

    work page

  2. [2]

    Since we assume that the electron moves only along the x′ axis connecting the two poten- tial minima, the relevant spatial dependence reduces to the one-dimensional coordinate x′

    Ponderomotive effect The ponderomotive effect is generated by an inho- mogeneous microwave driving field acting on a moving charged particle. Since we assume that the electron moves only along the x′ axis connecting the two poten- tial minima, the relevant spatial dependence reduces to the one-dimensional coordinate x′. Here, E(x′) denotes the magnitude o...

    work page

  3. [3]

    Monarkha and K

    Y. Monarkha and K. Kono, Two-dimensional coulomb liquids and solids , Springer Series in Solid-State Sciences (Springer, Berlin, Germany, 2004)

    work page 2004

  4. [4]

    E. Y. Andrei, Two-Dimensional Electron Systems : on Helium and other Cryogenic Substrates (Springer Nether- lands, 1997)

    work page 1997

  5. [5]

    W. Guo, D. Konstantinov, and D. Jin, Quantum elec- tronics on quantum liquids and solids, Progress in Quan- tum Electronics 99, 100552 (2025)

    work page 2025

  6. [6]

    P. M. Platzman and M. I. Dykman, Quantum Computing with Electrons Floating on Liquid Helium, Science 284, 1967 (1999)

    work page 1967

  7. [7]

    M. Lea, P. Frayne, and Y. Mukharsky, Could we Quan- tum Compute with Electrons on Helium?, Fortschr. Phys. 48, 1109 (2000)

    work page 2000

  8. [8]

    S. A. Lyon, Spin-based quantum computing using elec- trons on liquid helium, Phys. Rev. A 74, 052338 (2006)

    work page 2006

  9. [9]

    D. I. Schuster, A. Fragner, M. I. Dykman, S. A. Lyon, and R. J. Schoelkopf, Proposal for Manipulating and De- tecting Spin and Orbital States of Trapped Electrons on Helium Using Cavity Quantum Electrodynamics, Phys. Rev. Lett. 105, 040503 (2010)

    work page 2010

  10. [10]

    Kawakami, J

    E. Kawakami, J. Chen, M. Benito, and D. Konstantinov, Blueprint for quantum computing using electrons on he- lium, Phys. Rev. Appl. 20, 054022 (2023)

    work page 2023

  11. [11]

    Jennings, X

    A. Jennings, X. Zhou, I. Grytsenko, and E. Kawakami, Quantum computing using floating electrons on cryogenic substrates: Potential and challenges, Appl. Phys. Lett. 124, 120501 (2024)

    work page 2024

  12. [12]

    Koolstra, G

    G. Koolstra, G. Yang, and D. I. Schuster, Coupling a single electron on superfluid helium to a superconducting resonator, Nat. Commun. 10, 5323 (2019)

    work page 2019

  13. [13]

    Koolstra, E

    G. Koolstra, E. Glen, N. Beysengulov, H. Byeon, K. Cas- toria, M. Sammon, B. Dizdar, C. Wang, D. Schuster, S. Lyon, J. Pollanen, and D. Rees, High-impedance res- onators for strong coupling to an electron on helium, Phys. Rev. Appl. 23, 024001 (2025)

    work page 2025

  14. [14]

    Strong coupling of a microwave photon to an electron on helium

    G. Koolstra, E. O. Glen, N. R. Beysengulov, H. Byeon, K. E. Castoria, M. Sammon, S. A. Lyon, D. G. Rees, and J. Pollanen, Strong coupling of a microwave photon to an electron on helium, (2025), arXiv:2509.14506

    work page internal anchor Pith review Pith/arXiv arXiv 2025

  15. [15]

    X. Zhou, G. Koolstra, X. Zhang, G. Yang, X. Han, B. Dizdar, X. Li, R. Divan, W. Guo, K. W. Murch, D. I. Schuster, and D. Jin, Single electrons on solid neon as a solid-state qubit platform, Nature 605, 46 (2022)

    work page 2022

  16. [16]

    X. Zhou, X. Li, Q. Chen, G. Koolstra, G. Yang, B. Diz- dar, Y. Huang, C. S. Wang, X. Han, X. Zhang, D. I. Schuster, and D. Jin, Electron charge qubit with 0.1 mil- lisecond coherence time, Nat. Phys. 20, 116 (2024)

    work page 2024

  17. [17]

    X. Li, C. S. Wang, B. Dizdar, Y. Huang, Y. Wen, W. Guo, X. Zhang, X. Han, X. Zhou, and D. Jin, Solid neon as a noise-resilient host for electron qubits above 100 mk, Nat. Electron. , 1 (2026)

    work page 2026

  18. [18]

    X. Li, Y. Huang, X. Han, X. Zhou, and D. Jin, Coherent manipulation of interacting electron qubits on solid neon, (2025), arXiv:2503.23738

    work page arXiv 2025

  19. [19]

    S. Zou, X. Li, Q. Chen, and D. Jin, Electron charge co- herence on a solid neon surface, Quantum Science and Technology 11, 025003 (2026), arXiv:2507.20476

    work page arXiv 2026

  20. [20]

    Q. Chen, I. Martin, L. Jiang, and D. Jin, Electron spin coherence on a solid neon surface, Quantum Sci. Technol. 7, 045016 (2022)

    work page 2022

  21. [21]

    Samkharadze, A

    N. Samkharadze, A. Bruno, P. Scarlino, G. Zheng, D. P. DiVincenzo, L. DiCarlo, and L. M. K. Vandersypen, High-kinetic-inductance superconducting nanowire res- onators for circuit qed in a magnetic field, Phys. Rev. Appl. 5, 044004 (2016)

    work page 2016

  22. [22]

    Samkharadze, G

    N. Samkharadze, G. Zheng, N. Kalhor, D. Brousse, A. Sammak, U. C. Mendes, A. Blais, G. Scappucci, and L. M. K. Vandersypen, Strong spin-photon coupling in silicon., Science 359, 1123 (2018)

    work page 2018

  23. [23]

    J. G. Kroll, F. Borsoi, K. L. van der Enden, W. Uilhoorn, D. de Jong, M. Quintero-Pérez, D. J. van Woerkom, A. Bruno, S. R. Plissard, D. Car, E. P. A. M. Bakkers, M. C. Cassidy, and L. P. Kouwenhoven, Magnetic-field- resilient superconducting coplanar-waveguide resonators for hybrid circuit quantum electrodynamics experiments, Phys. Rev. Appl. 11, 064053 (2019)

    work page 2019

  24. [24]

    Y. Tian, I. Grytsenko, A. Jennings, J. Wang, H. Ikegami, X. Zhou, S. Tamate, H. Terai, H. Kutsuma, D. Jin, M. Benito, and E. Kawakami, Nb-ti-n nanowire res- onators and prospects for spin-photon coupling with elec- trons on solid neon, Phys. Rev. Appl. 25, 024011 (2025)

    work page 2025

  25. [25]

    Kanai, D

    T. Kanai, D. Jin, and W. Guo, Single-electron qubits based on quantum ring states on solid neon surface, Phys. Rev. Lett. 132, 250603 (2024)

    work page 2024

  26. [26]

    Tokura, W

    Y. Tokura, W. G. van der Wiel, T. Obata, and S. Tarucha, Coherent Single Electron Spin Control in a Slanting Zeeman Field, Phys. Rev. Lett. 96, 047202 (2006)

    work page 2006

  27. [27]

    Pioro-Ladrière, T

    M. Pioro-Ladrière, T. Obata, Y. Tokura, Y.-S. Shin, T. Kubo, K. Yoshida, T. Taniyama, and S. Tarucha, Elec- trically driven single-electron spin resonance in a slanting Zeeman field, Nat. Phys. 4, 776 (2008)

    work page 2008

  28. [28]

    D. J. Ibberson, T. Lundberg, J. A. Haigh, L. Hutin, B. Bertrand, S. Barraud, C.-M. Lee, N. A. Stelmashenko, G. A. Oakes, L. Cochrane, J. W. A. Robinson, M. Vinet, M. F. Gonzalez-Zalba, and L. A. Ibberson, Large disper- sive interaction between a cmos double quantum dot and microwave photons, PRX Quantum 2, 020315 (2021)

    work page 2021

  29. [29]

    Hayashi, T

    T. Hayashi, T. Fujisawa, H. D. Cheong, Y. H. Jeong, and Y. Hirayama, Coherent manipulation of electronic States in a double quantum dot., Phys. Rev. Lett. 91, 226804 (2003)

    work page 2003

  30. [30]

    W. G. van der Wiel, S. De Franceschi, J. M. Elzerman, T. Fujisawa, S. Tarucha, and L. P. Kouwenhoven, Elec- tron transport through double quantum dots, Reviews of Modern Physics 75, 1 (2002)

    work page 2002

  31. [31]

    I. I. Rabi, S. Millman, P. Kusch, and J. R. Zacharias, The molecular beam resonance method for measuring nuclear magnetic moments. the magnetic moments of 3Li6, 3Li7 and 9F19, Phys. Rev. 55, 526 (1939)

    work page 1939

  32. [32]

    N. F. Ramsey, A molecular beam resonance method with separated oscillating fields, Phys. Rev. 78, 695 (1950)

    work page 1950

  33. [33]

    Hahn, Spin Echoes, Physical Review 80, 580 (1950)

    E. Hahn, Spin Echoes, Physical Review 80, 580 (1950)

    work page 1950

  34. [34]

    Duthaluru, K

    S. Duthaluru, K. Zheng, E. A. Henriksen, and K. W. Murch, Real-time Monitoring of Neon Film Growth for Electron-on-Neon Qubits, Physical Review Applied 25, 044065 (2025)

    work page 2025

  35. [35]

    Pioro-Ladrière, Y

    M. Pioro-Ladrière, Y. Tokura, T. Obata, T. Kubo, and S. Tarucha, Micromagnets for coherent control of spin- charge qubit in lateral quantum dots, App. Phys. Lett. 15 90, 024105 (2007)

    work page 2007

  36. [36]

    Benito, X

    M. Benito, X. Croot, C. Adelsberger, S. Putz, X. Mi, J. R. Petta, and G. Burkard, Electric-field control and noise protection of the flopping-mode spin qubit, Phys. Rev. B. 100, 125430 (2019)

    work page 2019

  37. [37]

    Croot, X

    X. Croot, X. Mi, S. Putz, M. Benito, F. Borjans, G. Burkard, and J. R. Petta, Flopping-mode electric dipole spin resonance, Phys. Rev. Res. 2, 012006 (2020)

    work page 2020

  38. [38]

    K. D. Petersson, L. W. McFaul, M. D. Schroer, M. Jung, J. M. Taylor, A. A. Houck, and J. R. Petta, Circuit quan- tum electrodynamics with a spin qubit., Nature 490, 380 (2012)

    work page 2012

  39. [39]

    Dijkema, X

    J. Dijkema, X. Xue, P. Harvey-Collard, et al. , Cavity- mediated iswap oscillations between distant spins, Nat. Phys. 21, 168 (2025)

    work page 2025

  40. [40]

    X. Mi, J. V. Cady, D. M. Zajac, J. Stehlik, L. F. Edge, and J. R. Petta, Circuit quantum electrodynamics archi- tecture for gate-defined quantum dots in silicon, Applied Physics Letters 110, 043502 (2017)

    work page 2017

  41. [41]

    Braik, I

    M. Braik, I. Sow, J. Nelayah, A. Belkhir, M. Faustini, S. Mercone, S. Nowak, P. Decorse, J.-Y. Piquemal, and N. Félidj, Introducing cobalt as a potential plasmonic candidate combining optical and magnetic functionali- ties within the same nanostructure, Nanoscale 13, 2639 (2021)

    work page 2021

  42. [42]

    Blais, R.-S

    A. Blais, R.-S. Huang, A. Wallraff, S. M. Girvin, and R. J. Schoelkopf, Cavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation, Phys. Rev. A 69, 062320 (2004)

    work page 2004

  43. [43]

    T. W. B. Kibble, Mutual refraction of electrons and pho- tons, Phys. Rev. 150, 1060 (1966)

    work page 1966

  44. [44]

    P. H. Bucksbaum, R. R. Freeman, M. Bashkansky, and T. J. McIlrath, Role of the ponderomotive potential in above-threshold ionization, J. Opt. Soc. Am. B 4, 760 (1987)

    work page 1987