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Both transverse XY and longitudinal Z controls for fluxonium qubits run through one shared flux-control channel.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

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2026-06-29 22:07 UTC pith:PLQTLJ5D

load-bearing objection Single flux line with filtering and compensation works for fluxonium at the reported high fidelities and coherence, addressing a real hardware scaling issue.

arxiv 2605.25948 v2 pith:PLQTLJ5D submitted 2026-05-25 quant-ph

Unified Flux Control Architecture for Fluxonium Qubits

Xianchuang Pan , Jiahui Wang , Tao Zhou , Yanbo Guo , Fei Wang , Ze Zhan , Liang Xiang , Zishuo Li
show 9 more authors
Lu Ma Xizheng Ma Huijuan Zhan Tao Zhang Kannan Lu Xing Zhu Guicheng Gong Chunqing Deng Tenghui Wang
This is my paper
classification quant-ph
keywords fluxonium qubitsunified flux controlsuperconducting quantum computingqubit control architecturecryogenic filteringwaveform synthesisactive resetsingle-qubit gates
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 a unified control architecture where a single flux line, driven by one waveform generator channel, performs both XY gates and Z reset operations on fluxonium qubits. This is made possible by frequency-selective cryogenic filtering combined with compensated waveform synthesis to handle the conflicting demands of low-frequency signals for reset and noise suppression at qubit frequencies. If successful, this approach reduces the hardware overhead for controlling superconducting qubits, which is critical for building larger processors. The experiments show coherence times remain above 100 microseconds, with reset fidelity around 98 percent and gate fidelities over 99.99 percent in 20 nanoseconds. It also includes FPGA-based waveform synthesis using pulse primitives.

Core claim

Both transverse (XY) and longitudinal (Z) operations are implemented through a single flux-control channel driven by a single arbitrary waveform generator channel, addressed via frequency-selective cryogenic filtering together with compensated waveform synthesis that corrects pulse distortion, preserving coherence times above 100 μs while enabling active reset with approximately 98% fidelity and 20-ns single-qubit gates with fidelities exceeding 99.99%.

What carries the argument

The unified flux-control channel with frequency-selective cryogenic filtering and compensated waveform synthesis that supports low-frequency reset while attenuating noise near the qubit frequency.

Load-bearing premise

Frequency-selective cryogenic filtering together with compensated waveform synthesis can simultaneously support low-frequency flux transmission for reset while strongly attenuating broadband noise near the qubit transition frequency without introducing uncharacterized errors.

What would settle it

Measuring coherence times below 100 μs or single-qubit gate fidelities below 99.99% on the same fluxonium device when switching from separate control lines to the unified single-channel method.

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

If this is right

  • Reduces control hardware overhead by using one channel and one generator per qubit for both XY and Z operations.
  • Preserves coherence times above 100 μs under the unified drive.
  • Enables active reset with approximately 98% fidelity.
  • Achieves 20-ns single-qubit gates with fidelities exceeding 99.99%.
  • Supports FPGA-native instruction-level waveform synthesis based on reusable pulse primitives.

Where Pith is reading between the lines

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

  • This single-channel method could halve the number of control lines required in multi-qubit fluxonium arrays.
  • The filtering and compensation approach might extend to other flux-tunable superconducting qubits beyond fluxonium.
  • Shared control lines in larger processors would require checking whether crosstalk stays below error-correction thresholds.
  • Repeated reset-and-gate cycles under unified control could be timed to measure impact on error-correction overhead.

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

0 major / 0 minor

Summary. The manuscript experimentally demonstrates a unified flux control architecture for fluxonium qubits in which both transverse (XY) and longitudinal (Z) operations are realized through a single flux-control channel driven by one arbitrary waveform generator channel. Frequency-selective cryogenic filtering combined with compensated waveform synthesis is used to satisfy the competing demands of low-frequency transmission for active reset and strong attenuation of noise near the qubit frequency. Reported performance includes coherence times above 100 μs, active reset fidelity of approximately 98%, 20-ns single-qubit gates with fidelities exceeding 99.99%, and FPGA-native instruction-level waveform synthesis using reusable pulse primitives.

Significance. If the experimental results hold, the work would be significant for scaling superconducting processors by reducing control hardware overhead while preserving the high coherence and gate fidelity that make fluxonium qubits attractive. The direct experimental metrics (coherence, reset fidelity, gate fidelity) serve as the test of whether residual noise or distortion remains within the error budget, and the FPGA-native synthesis component adds practical value for control electronics.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript, accurate summary of the results, and recommendation for minor revision. The significance statement correctly identifies the relevance to scaling superconducting processors.

Circularity Check

0 steps flagged

No significant circularity; experimental demonstration is self-contained

full rationale

The paper reports an experimental implementation of unified flux control for fluxonium qubits using a single channel with cryogenic filtering and waveform compensation. Performance is validated directly by measured quantities (T1,T2 >100 μs, reset fidelity ~98%, gate fidelity >99.99%) rather than by any derivation, fitted prediction, or self-citation chain that reduces the result to its inputs by construction. No equations, ansatzes, or uniqueness theorems are invoked in a load-bearing way; the architecture's viability is tested by the reported hardware metrics themselves.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review provides no explicit free parameters, axioms, or invented entities; the demonstration rests on standard cryogenic electronics techniques.

pith-pipeline@v0.9.1-grok · 5768 in / 1043 out tokens · 42314 ms · 2026-06-29T22:07:03.329729+00:00 · methodology

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read the original abstract

Control architectures that reduce hardware overhead while maintaining high-fidelity operations are essential for the continued scaling of superconducting quantum processors. Here we experimentally realize a unified control architecture for fluxonium qubits, in which both transverse ($XY$) and longitudinal ($Z$) operations are implemented through a single flux-control channel driven by a single arbitrary waveform generator channel. This architecture imposes competing requirements on the shared control channel, which must simultaneously support low-frequency flux transmission for reset operations while strongly attenuating broadband noise near the qubit transition frequency. We address this challenge through frequency-selective cryogenic filtering together with compensated waveform synthesis that corrects the pulse distortion introduced by the filtered control line. Experimentally, this approach preserves coherence times above 100 $\mu$s while enabling active reset with approximately 98% fidelity and 20-ns single-qubit gates with fidelities exceeding 99.99%. We further demonstrate FPGA-native instruction-level waveform synthesis based on reusable pulse primitives for unified flux control. These results establish unified flux control as a scalable architecture for fluxonium qubits that reduces control hardware overhead while preserving high-fidelity operation.

Figures

Figures reproduced from arXiv: 2605.25948 by Chunqing Deng, Fei Wang, Guicheng Gong, Huijuan Zhan, Jiahui Wang, Kannan Lu, Liang Xiang, Lu Ma, Tao Zhang, Tao Zhou, Tenghui Wang, Xianchuang Pan, Xing Zhu, Xizheng Ma, Yanbo Guo, Ze Zhan, Zishuo Li.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: (b). In this way, control is implemented through dynamic signal synthesis rather than stored waveform re￾play. Experimentally, the synthesized output waveform, including simultaneous baseband and microwave￾modulated components (i.e., XY +Z), closely matches the designed structure [ [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4 [PITH_FULL_IMAGE:figures/full_fig_p008_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5 [PITH_FULL_IMAGE:figures/full_fig_p009_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6 [PITH_FULL_IMAGE:figures/full_fig_p010_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7 [PITH_FULL_IMAGE:figures/full_fig_p011_7.png] view at source ↗

discussion (0)

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Reference graph

Works this paper leans on

48 extracted references · 6 canonical work pages · 1 internal anchor

  1. [1]

    LetVawg(t)be the room-temperature voltage signal

    Rabi Drive Strength from Room-Temperature Voltage To connect the drive Hamiltonian to the room- temperature control electronics, we express the drive cur- rentI d(t)in terms of the voltage generated by the ar- bitrary waveform generator (AWG). LetVawg(t)be the room-temperature voltage signal. The control line in- cludes a series of attenuators with a tota...

  2. [2]

    Tail over Ref

    Relaxation Time Degradation Induced by Room-Temperature White Noise In addition to the coherent drive, the physical con- nection to room-temperature electronics introduces wide- band noise, which can stimulate spurious transitions and degrade the qubit relaxation timeT1. The noise current on the flux line is characterized by its quantum noise spectral den...

  3. [3]

    A. P. Place, L. V. Rodgers, P. Mundada, B. M. Smitham, M. Fitzpatrick, Z. Leng, A. Premkumar, J. Bryon, A. Vrajitoarea, S. Sussman,et al., Nat. Commun.12, 1779 (2021)

    2021

  4. [4]

    Ganjam, Y

    S. Ganjam, Y. Wang, Y. Lu, A. Banerjee, C. U. Lei, L. Krayzman, K. Kisslinger, C. Zhou, R. Li, Y. Jia,et al., Nat. Commun.15, 3687 (2024)

    2024

  5. [5]

    L. B. Nguyen, Y.-H. Lin, A. Somoroff, R. Mencia, N. Grabon, and V. E. Manucharyan, Phys. Rev. X9, 041041 (2019)

    2019

  6. [6]

    Somoroff, Q

    A. Somoroff, Q. Ficheux, R. A. Mencia, H. Xiong, R. Kuzmin, and V. E. Manucharyan, Phys. Rev. Lett. 130, 267001 (2023)

    2023

  7. [7]

    F. Wang, K. Lu, H. Zhan, L. Ma, F. Wu, H. Sun, H. Deng, Y. Bai, F. Bao, X. Chang, R. Gao, X. Gao, G. Gong, L. Hu, R. Hu, H. Ji, X. Ma, L. Mao, Z. Song, C. Tang,et al., Phys. Rev. Appl.23, 044064 (2025)

    2025

  8. [8]

    Y. Sung, L. Ding, J. Braumüller, A. Vepsäläinen, B. Kan- nan, M. Kjaergaard, A. Greene, G. O. Samach, C. Mc- Nally, D. Kim,et al., Phys. Rev. X11, 021058 (2021)

    2021

  9. [9]

    Negîrneac, H

    V. Negîrneac, H. Ali, N. Muthusubramanian, F. Battis- tel, R. Sagastizabal, M. S. Moreira, J. F. Marques, W. J. Vlothuizen, M. Beekman, C. Zachariadis, N. Haider, A. Bruno, and L. DiCarlo, Phys. Rev. Lett.126, 220502 (2021)

    2021

  10. [10]

    L. Ding, M. Hays, Y. Sung, B. Kannan, J. An, A. Di Paolo, A. H. Karamlou, T. M. Hazard, K. Azar, D. K. Kim, B. M. Niedzielski, A. Melville, M. E. Schwartz, J. L. Yoder, T. P. Orlando, S. Gustavsson, J. A. Grover, K. Serniak, and W. D. Oliver, Phys. Rev. X13, 031035 (2023)

    2023

  11. [11]

    D. A. Rower, L. Ding, H. Zhang, M. Hays, J. An, P. M. Harrington, I. T. Rosen, J. M. Gertler, T. M. Hazard, B.M.Niedzielski,et al.,PRXQuantum5,040342(2024)

    2024

  12. [12]

    Z. Zhan, Z. Li, F. Wang, W. Lan, X. Pan, L. Xiang, X. Dou, R. Gao, G. Gong, Y. Guo,et al., arXiv preprint arXiv:2604.13363 (2026), arXiv:2604.13363

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  13. [13]

    Arute, K

    F. Arute, K. Arya, R. Babbush, D. Bacon, J. C. Bardin, R. Barends, R. Biswas, S. Boixo, F. G. Brandao, D. A. Buell,et al., Nature574, 505 (2019)

    2019

  14. [14]

    Wu, W.-S

    Y. Wu, W.-S. Bao, S. Cao, F. Chen, M.-C. Chen, X.Chen, T.-H.Chung, H.Deng, Y.Du, D.Fan, M.Gong, C. Guo, C. Guo, S. Guo, L. Han, L. Hong, H.-L. Huang, Y.-H. Huo, L. Li, N. Li,et al., Phys. Rev. Lett.127, 180501 (2021)

    2021

  15. [15]

    Y. Kim, A. Eddins, S. Anand, K. X. Wei, E. Van Den Berg, S. Rosenblatt, H. Nayfeh, Y. Wu, M. Zale- tel, K. Temme,et al., Nature618, 500 (2023)

    2023

  16. [16]

    Van Damme, S

    J. Van Damme, S. Massar, R. Acharya, T. Ivanov, D. Perez Lozano, Y. Canvel, M. Demarets, D. Vangoid- senhoven, Y. Hermans, J. Lai,et al., Nature634, 74 (2024)

    2024

  17. [17]

    F. Jin, S. Jiang, X. Zhu, Z. Bao, F. Shen, K. Wang, Z.Zhu, S.Xu, Z.Song, J.Chen, Z.Tan, Y.Wu, C.Zhang, Y. Gao, N. Wang, Y. Zou, A. Zhang, T. Li, J. Zhong, Z. Cui,et al., Nature645, 626 (2025)

    2025

  18. [18]

    J. Koch, T. M. Yu, J. Gambetta, A. A. Houck, D. I. Schuster, J. Majer, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, Phys. Rev. A76, 042319 (2007)

    2007

  19. [19]

    V. E. Manucharyan, J. Koch, L. I. Glazman, and M. H. Devoret, Science326, 113 (2009)

    2009

  20. [20]

    Krantz, M

    P. Krantz, M. Kjaergaard, F. Yan, T. P. Orlando, S. Gustavsson, and W. D. Oliver, Appl. Phys. Rev.6, 10.1063/1.5089550 (2019)

    work page doi:10.1063/1.5089550 2019

  21. [21]

    Manenti, E

    R. Manenti, E. A. Sete, A. Q. Chen, S. Kulshreshtha, J.-H. Yeh, F. Oruc, A. Bestwick, M. Field, K. Jackson, and S. Poletto, Appl. Phys. Lett.119, 10.1063/5.0065517 (2021)

    work page doi:10.1063/5.0065517 2021

  22. [22]

    Yan, Z.-Y

    Z. Yan, Z.-Y. Ge, R. Li, Y.-R. Zhang, F. Nori, and Y. Nakamura, Sci. Adv.12, eaeb8213 (2026)

    2026

  23. [23]

    Zhang, S

    H. Zhang, S. Chakram, T. Roy, N. Earnest, Y. Lu, Z. Huang, D. K. Weiss, J. Koch, and D. I. Schuster, Phys. Rev. X11, 011010 (2021)

    2021

  24. [24]

    Deng, J.-L

    C. Deng, J.-L. Orgiazzi, F. Shen, S. Ashhab, and A. Lu- pascu, Phys. Rev. Lett.115, 133601 (2015)

    2015

  25. [25]

    X. Ma, G. Zhang, F. Wu, F. Bao, X. Chang, J. Chen, H. Deng, R. Gao, X. Gao, L. Hu, H. Ji, H.-S. Ku, K. Lu, L. Ma, L. Mao, Z. Song, H. Sun, C. Tang, F. Wang, H. Wang,et al., Phys. Rev. Lett.132, 060602 (2024)

    2024

  26. [26]

    Ficheux, L

    Q. Ficheux, L. B. Nguyen, A. Somoroff, H. Xiong, K. N. Nesterov, M. G. Vavilov, and V. E. Manucharyan, Phys. Rev. X11, 021026 (2021)

    2021

  27. [27]

    F. Bao, H. Deng, D. Ding, R. Gao, X. Gao, C. Huang, X. Jiang, H.-S. Ku, Z. Li, X. Ma, X. Ni, J. Qin, Z. Song, H. Sun, C. Tang, T. Wang, F. Wu, T. Xia, W. Yu, F. Zhang,et al., Phys. Rev. Lett.129, 010502 (2022)

    2022

  28. [28]

    Huang, T

    C. Huang, T. Wang, F. Wu, D. Ding, Q. Ye, L. Kong, F. Zhang, X. Ni, Z. Song, Y. Shi, H.-H. Zhao, C. Deng, and J. Chen, Phys. Rev. Lett.130, 070601 (2023)

    2023

  29. [29]

    T. Wang, F. Wu, F. Wang, X. Ma, G. Zhang, J. Chen, H. Deng, R. Gao, R. Hu, L. Ma,et al., Phys. Rev. Lett. 132, 230601 (2024)

    2024

  30. [30]

    McEwen, D

    M. McEwen, D. Kafri, Z. Chen, J. Atalaya, K. Satzinger, C. Quintana, P. V. Klimov, D. Sank, C. Gidney, A. Fowler,et al., Nat. Commun.12, 1761 (2021)

    2021

  31. [31]

    M. D. Reed, B. R. Johnson, A. A. Houck, L. DiCarlo, J. M. Chow, D. I. Schuster, L. Frunzio, and R. J. Schoelkopf, Appl. Phys. Lett.96, 203110 (2010)

    2010

  32. [32]

    Keller, J

    S.Krinner, S.Storz, P.Kurpiers, P.Magnard, J.Heinsoo, R. Keller, J. Luetolf, C. Eichler, and A. Wallraff, EPJ Quantum Technol.6, 2 (2019)

    2019

  33. [33]

    Simbierowicz, M

    S. Simbierowicz, M. Borrelli, V. Monarkha, V. Nuutinen, and R. E. Lake, PRX Quantum5, 030302 (2024)

    2024

  34. [34]

    M. Xia, C. Zhou, C. Liu, P. Patel, X. Cao, P. Lu, B. Mesits, M. Mucci, D. Gorski, D. Pekker,et al., Nat. Commun. 10.1038/s41467-025-67766-6 (2025)

    work page doi:10.1038/s41467-025-67766-6 2025

  35. [35]

    Schirk, F

    J. Schirk, F. Wallner, L. Huang, I. Tsitsilin, N. Bruck- moser, L. Koch, D. Bunch, N. J. Glaser, G. B. Huber, M. Knudsen,et al., PRX Quantum6, 030315 (2025)

    2025

  36. [36]

    X.You, J.A.Sauls,andJ.Koch,Phys.Rev.B99,174512 (2019)

    2019

  37. [37]

    E. A. Sete, J. M. Gambetta, and A. N. Korotkov, Phys. 13 Rev. B89, 104516 (2014)

    2014

  38. [38]

    Magesan, J

    E. Magesan, J. M. Gambetta, B. R. Johnson, C. A. Ryan, J. M. Chow, S. T. Merkel, M. P. Da Silva, G. A. Keefe, M. B. Rothwell, T. A. Ohki,et al., Phys. Rev. Lett.109, 080505 (2012)

    2012

  39. [39]

    Y. Yang, Z. Shen, X. Zhu, Z. Wang, G. Zhang, J. Zhou, X. Jiang, C. Deng, and S. Liu, Rev. Sci. Instrum.93, 10.1063/5.0085467 (2022)

    work page doi:10.1063/5.0085467 2022

  40. [40]

    M. A. Rol, L. Ciorciaro, F. K. Malinowski, B. M. Tarasin- ski, R. E. Sagastizabal, C. C. Bultink, Y. Salathe, N. Haandbæk, J. Sedivy, and L. DiCarlo, Appl. Phys. Lett.116, 10.1063/1.5133894 (2020)

    work page doi:10.1063/1.5133894 2020

  41. [41]

    I. M. Pop, K. Geerlings, G. Catelani, R. J. Schoelkopf, L. I. Glazman, and M. H. Devoret, Nature508, 369 (2014)

    2014

  42. [42]

    Serniak, M

    K. Serniak, M. Hays, G. de Lange, S. Diamond, S. Shankar, L. D. Burkhart, L. Frunzio, M. Houzet, and M. H. Devoret, Phys. Rev. Lett.121, 157701 (2018)

    2018

  43. [43]

    Ithier, E

    G. Ithier, E. Collin, P. Joyez, P. J. Meeson, D. Vion, D. Esteve, F. Chiarello, A. Shnirman, Y. Makhlin, J.Schriefl,andG.Schön,Phys.Rev.B72,134519(2005)

    2005

  44. [44]

    Bylander, S

    J. Bylander, S. Gustavsson, F. Yan, F. Yoshihara, K. Harrabi, G. Fitch, D. G. Cory, Y. Nakamura, J.-S. Tsai, and W. D. Oliver, Nat. Phys.7, 565 (2011)

    2011

  45. [45]

    J. M. Martinis, K. B. Cooper, R. McDermott, M. Steffen, M. Ansmann, K. D. Osborn, K. Cicak, S. Oh, D. P. Pap- pas, R. W. Simmonds, and C. C. Yu, Phys. Rev. Lett. 95, 210503 (2005)

    2005

  46. [46]

    Müller, J

    C. Müller, J. H. Cole, and J. Lisenfeld, Rep. Prog. Phys. 82, 124501 (2019)

    2019

  47. [47]

    Yoshihara, K

    F. Yoshihara, K. Harrabi, A. O. Niskanen, Y. Nakamura, and J. S. Tsai, Phys. Rev. Lett.97, 167001 (2006)

    2006

  48. [48]

    Paladino, Y

    E. Paladino, Y. M. Galperin, G. Falci, and B. L. Alt- shuler, Rev. Mod. Phys.86, 361 (2014)

    2014