Pith. sign in

REVIEW 1 major objections 5 minor 41 references

Spectator Leakage Elimination in CZ Gates via Tunable Coupler Interference on a Superconducting Quantum Processor

T0 review · 1 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Pith's one-line read This paper claims that a spectator qubit's leakage out of a controlled-Z gate can be eliminated by dynamically tuning a coupler to enforce a block-diagonal Hamiltonian, and demonstrates leakage rates near 10^-4 on superconducting hardware.

desk verdict A well-executed, genuinely useful technique for suppressing spectator leakage in tunable-coupler CZ gates, with a caveat or two about framing. read the letter →

arxiv 2507.14531 v1 pith:HA2RTSV7 submitted 2025-07-19 quant-ph

Peng Wang , Bin-Han Lu , Tian-Le Wang , Sheng Zhang , Zhao-Yun Chen , Hai-Feng Zhang , Ren-Ze Zhao , Xiao-Yan Yang
show 6 more authors
Ze-An Zhao Zhuo-Zhi Zhang Xiang-Xiang Song Yu-Chun Wu Peng Duan Guo-Ping Guo
This is my paper · ORCID
classification quant-ph PACS 03.67.Lx03.67.Pp85.25.Cp
keywords spectatorleakagesuperconductingqubitstunablecouplercontrolled-Zgateblock-diagonalizationHamiltonianengineeringsuppressionsurfacecodethreshold
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

Superconducting quantum processors cannot avoid putting some qubits in near-resonant contact while a two-qubit gate runs, and those "spectator" qubits can pull population out of the gate's computational subspace, an error that is hard to correct. The paper claims a cure: during the CZ gate, pulse the tunable coupler to a specific off frequency, chosen so that the effective three-state Hamiltonian $\{|11\rangle, |02\rangle, |S\rangle\}$ becomes block-diagonal. The gate dynamics then stay inside a two-dimensional invariant subspace, so leakage is suppressed by construction rather than by hunting for special gate durations. Experiments on a five-qubit superconducting processor show the single-spectator leakage rate dropping from $1.21(5)\times10^{-3}$ to $4(3)\times10^{-5}$, and with three simultaneous spectators total leakage $1.9(4)\times10^{-4}$, below a surface-code-relevant threshold. The claimed consequence is that frequency crowding no longer forces spectator qubits into harmful configurations, easing the path to fault-tolerant processors.

What carries the argument

The central object is the bright/dark-state rotation on the $\{|02\rangle,|S\rangle\}$ subspace, with angle $\theta=\tan^{-1}(g_1/g_{\rm gate})$, together with the nulling condition $g_{BD}=0$. A block-diagonal Hamiltonian here means one with zero coupling between the two-level block $\{|11\rangle,|B\rangle\}$ and the dark state $|D\rangle$; that zero makes the bright block an invariant subspace, so the gate operator never transfers population out of it. The tunable coupler is the actuator: its frequency controls $g_2$, allowing the experiment to locate the zero of $g_{BD}$ and hold it during the gate, and the same condition generalizes to multiple spectators when each has its own tunable coupler.

What would settle it

On a device with the same l-h-s topology, put the spectator qubit near resonance, run a fixed-duration CZ gate, and sweep the spectator coupler frequency while measuring the $|011\rangle$ population; the model predicts a single leakage valley centered exactly where $g_{BD}=0$ computed from independently measured couplings. If the valley is shifted, absent, or does not disappear at the predicted off frequency, the block-diagonalization mechanism is not the operative one.

Watch

Extended reading notes

Core claim

At its core, the paper argues that near-resonant spectator leakage is governed by a single three-level interaction and that this interaction can be switched off by a physically realizable basis change. In the ordered basis $\{|11\rangle, |02\rangle, |S\rangle\}$, the effective Hamiltonian is $$H_{\rm eff}=\begin{pmatrix} \omega_{11} & g_{\rm gate} & g_1\\ g_{\rm gate} & \omega_{02} & g_2\\ g_1 & g_2 & \omega_S \end{pmatrix},$$ with $\omega_{11}=\omega_{02}$. Rotating $\{|02\rangle,|S\rangle\}$ through $\theta=\tan^{-1}(g_1/g_{\rm gate})$ sends one of the new basis states, the dark state $|D\rangle$, out of the dynamics whenever $g_{BD}=\frac{\omega_S-\omega_{11}}{2}\sin 2\theta + g_2\cos 2\theta = 0$. Since $g_2$ depends on the spectator-coupler frequency, the experiment can pulse that coupler to the value that nulls $g_{BD}$, leaving the gate to evolve in the two-dimensional invariant subspace $\{|11\rangle,|B\rangle\}$ as an ordinary CZ gate with effective coupling $\sqrt{g_{\rm gate}^2+g_1^2}$. This is the block-diagonalization claim: the Hamiltonian separates into two disconnected blocks, so leakage to $|D\rangle$ is impossible by construction. The paper then demonstrates on hardware that the measured leakage valley sits at the predicted off frequency, with single-spectator leakage falling from $1.21(5)\times10^{-3}$ to $4(3)\times10^{-5}$.

Load-bearing premise

The dominant spectator leakage must pass through a coupling the tunable coupler can change; if fixed stray capacitance dominates that channel, the cancellation condition cannot be reached, a limitation the paper explicitly concedes.

Editorial extensions

If this is right

  • A CZ gate can be run while a spectator qubit sits at a frequency that would previously have been forbidden, removing the requirement of large frequency separation during parallel operations.
  • Leakage rates near $10^{-4}$ across the near-resonant detuning range mean this specific coherent error channel no longer dominates gate error when spectator qubits must be close in frequency.
  • With three simultaneous spectators, total leakage of $1.9(4)\times10^{-4}$ stays below thresholds relevant for surface-code error correction, so the protocol scales to multi-spectator neighborhoods.
  • The measured reduction in total gate error is quantitatively consistent with the suppressed leakage contribution ($\Delta\epsilon\approx\frac{5}{4}\Delta L_1$), indicating the method removes the leakage pathway without adding comparable new errors.
  • For multiple spectators, each coupler can be set to the same independently calibrated off condition, because in the weak-coupling limit the optimal $g_2$ for one spectator does not depend on the others.

Reading between the lines

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

  • (Inference) Because the paper shows the residual single-spectator leakage sits at the readout and decoherence floor, a next test is to rerun the same protocol on a device with higher-fidelity readout; the model predicts the achieved leakage bound would drop below $10^{-5}$.
  • (Inference) The same $g_{BD}=0$ block-diagonalization should apply to any spectator-mediated error with a tunable coupling, including residual ZZ crosstalk or leakage in other two-qubit gates such as iSWAP, so the technique may be portable beyond CZ gates.
  • (Inference) The observed independence of leakage per spectator suggests a large-chip calibration shortcut: characterize one spectator's optimal coupler pulse and reuse it across all identical neighborhoods, then correct only flux crosstalk, rather than searching each coupler separately.
  • (Inference) Combining the nulling condition with optimal-control pulse shaping could trade the present constant-frequency off pulse for a shaped trajectory that maintains $g_{BD}=0$ while reducing transient excitations at the pulse edges.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

1 major / 5 minor

Summary. The paper proposes and experimentally tests a method to suppress spectator-induced leakage during fast flux-tunable CZ gates. The theoretical core is a three-level model in the basis {|11>, |02>, |S>}; a rotation of |02> and |S> into bright and dark states block-diagonalizes the effective Hamiltonian when Eq. (4), gBD = 0, is satisfied, and the authors argue that a tunable spectator coupler provides the control needed to reach this condition. Numerical simulations show a leakage-suppression valley at the predicted coupler frequency. Experiments on the Wukong processor show the per-gate spectator leakage decreasing from 1.21(5)e-3 to 4(3)e-5 for one spectator, agreement between the measured optimal coupler frequency and the model across a range of detunings, and a total leakage of 1.9(4)e-4 with three simultaneous spectators. The supplementary material contains the Schrieffer-Wolff derivation, spectroscopy-based parameter extraction, the leakage-amplification and XEB analysis, and an extension to multiple spectator levels.

Significance. If the results hold, this is a practically relevant contribution to a known scalability bottleneck: spectator-induced leakage in frequency-crowded superconducting processors. The central mechanism is clean and the model is genuinely predictive rather than fitted: the parameters g1, g2, and ggate are extracted from independent spectroscopy (Supplementary III.A), and the predicted gBD = 0 condition is compared with measured leakage minima. The single-spectator suppression factor of roughly 30 and the consistency between the measured leakage reduction and the XEB error reduction (Supplementary III.C) are convincing. The multi-spectator additivity is supported by component-level measurements in Supplementary III.E. The main limitation, acknowledged by the authors, is that the suppressed leakage rate is at the measurement resolution, so the experiment establishes an upper bound of order 1e-4 rather than a true null; this should be reflected in the wording but does not undermine the central mechanism.

major comments (1)
  1. [Supplementary I.B-I.C, Eqs. (S27)-(S29)] The multi-spectator closure equations are internally inconsistent with the main-text condition. Eq. (S27) should have the spectator-state energy on the left-hand side, i.e., g_gate*g2,i + g1,i*omega_Si = g1,i*omega_B, rather than omega_11. With omega_11 in that equation, the system does not reduce to the single-spectator condition in Eq. (4). Solving the corrected equations for n = 1 with omega_02 = omega_11 gives g2 = -g1*g_gate*(omega_S - omega_11)/(g_gate^2 - g1^2), which in the weak-coupling limit is g2 ≈ -g1*(omega_S - omega_11)/g_gate. Eq. (S29), by contrast, gives the opposite sign. Eq. (S28) is also not the solution of the displayed Eqs. (S26)-(S27): its denominator g_gate*(g_B^2 - g1,i^2) and its numerator do not match a direct re-derivation for the multi-spectator Hamiltonian. Because this theoretical step is used to justify the independence of the optimal spectator-coupler settings in the multi-spectator protocol, the derivation should be corrected and the numerical predictions re-checked. The experimental additivity analysis in Supplementary III.E is not affected, but the supporting theory must be made consistent with Eq. (4).
minor comments (5)
  1. [Abstract and Conclusions] The phrase "preventing leakage by construction" is stronger than what the analysis and experiment establish: the block-diagonalization is exact only within the truncated three-level model, and the measured floor of 4(3)e-5 is at the readout/decoherence resolution limit (Supplementary III.D). Please qualify the wording, for example by saying "within the three-level model" and describing the measured suppressed rate as an upper bound.
  2. [Fig. 3(e)] The claimed agreement between the experimental optimal coupler frequencies and the theoretical prediction is presented visually; please state explicitly that the white dashed line is obtained solely from independently measured parameters (Supplementary III.A) with no fit to the leakage-minimum data, and provide residuals or an uncertainty band so the agreement is quantitative.
  3. [Supplementary I.C] The discussion of the generalized bright-state closure says that the conditions impose n+1 constraint equations, but omega_B is also an unknown in those equations; please clarify the counting of equations and free parameters (n tunable g2 values plus omega_B) so the solvability argument is transparent.
  4. [Conclusions and Fig. 4] The statement that the total leakage with three spectators is below "the threshold relevant for surface code error correction" should be quantified with a specific threshold value and a citation; as written, the claim is too vague to be assessed.
  5. [Fig. 2(a)] The y-axis tick labels appear as "-g_gate", "0", "g_gate"; please clarify in the caption whether the vertical axis is in MHz or in units of g_gate, and define omega_off_cs where it first appears.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the optimal-coupler-frequency prediction is tested against independently measured leakage minima, and the central claim does not reduce to a fit or to a self-citation.

full rationale

The derivation chain is self-contained. The effective three-level Hamiltonian of Eq. (1) is obtained by a Schrieffer-Wolff transformation from the full circuit Hamiltonian (Supplementary I.A), and the parameters g1, g2, and ggate are characterized independently by two-photon spectroscopy of avoided crossings (Supplementary III.A), not by fitting to the leakage-suppression data. The block-diagonalization condition gBD = 0, Eq. (4), is a derived algebraic condition on the measured matrix elements; the predicted optimal spectator-coupler frequency is then compared with experimentally measured leakage minima in Fig. 3(e), which is a genuine model test. The statement that leakage is prevented 'by construction' refers to the ideal truncated three-level model, and the paper explicitly acknowledges the scope limitation that leakage dominated by fixed stray couplings outside the tunable pathway is not suppressed (Conclusions; Supplementary Table S1 and surrounding text). The observed leakage floor of ~1e-4 is consistent with the independently estimated readout/decoherence resolution limit (Supplementary III.D). Self-citations appear only for supporting methods — flux-crosstalk calibration [13], frequency allocation [30], and an introductory citation on frequency crowding [22] — and none is load-bearing for the leakage-elimination claim. No circular step, fitted-input-called-prediction, or author-imported uniqueness argument was found.

Assumptions & free parameters 4 free parameters · 4 assumptions · 0 invented entities

The central claim rests on a three-level model with parameters measured on the device; the main assumption is that the tunable coupler can null the leakage coupling, which is verified by experiment. No new physical entities are introduced.

free parameters (4)
  • g1 = ~0.5 MHz
    Effective coupling between |11> and spectator state |S>, extracted from two-photon spectroscopy (Supplementary III.A).
  • g2 = function of coupler frequency
    Effective coupling between |02> and |S>, tuned by spectator coupler frequency, extracted from spectroscopy.
  • ggate = 27 MHz
    Effective gate coupling between |11> and |02>, used in simulations and model.
  • gate duration tau = 40 ns
    Calibrated CZ gate duration used in experiments.
assumptions (4)
  • domain assumption The three-level truncation of the system dynamics
    The effective Hamiltonian in Eq. (1) retains only |11>, |02>, |S>, neglecting other levels and higher-order processes. This is standard for near-resonant CZ operations but omits fixed stray coupling leakage paths.
  • standard math Schrieffer-Wolff transformation validity
    Used to derive effective couplings from the full circuit Hamiltonian; perturbative second-order treatment assumes couplers remain in ground state.
  • domain assumption Independence of spectator qubits
    The multi-spectator model in Supplementary I.C assumes negligible spectator-spectator interactions, allowing linear additivity. Verified experimentally for three spectators (Supplementary III.E).
  • domain assumption Resonance condition omega11 = omega02
    The block-diagonalization condition gBD uses omega11 = omega02, which is the CZ operating point.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Spectator Leakage Elimination in CZ Gates via Tunable Coupler Interference on a Superconducting Quantum Processor." pith.science (2026). https://pith.science/paper/HA2RTSV7

@misc{pith2026250714531,
  author       = {Pith},
  title        = {Pith review of: Spectator Leakage Elimination in CZ Gates via Tunable Coupler Interference on a Superconducting Quantum Processor},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/HA2RTSV7}},
  note         = {Machine review of arXiv:2507.14531}
}
abstract

Spectator-induced leakage poses a fundamental challenge to scalable quantum computing, particularly as frequency collisions become unavoidable in multi-qubit processors. We introduce a leakage mitigation strategy based on dynamically reshaping the system Hamiltonian. Our technique utilizes a tunable coupler to enforce a block-diagonal structure on the effective Hamiltonian governing near-resonant spectator interactions, confining the gate dynamics to a two-dimensional invariant subspace and thus preventing leakage by construction. On a multi-qubit superconducting processor, we experimentally demonstrate that this dynamic control scheme suppresses leakage rates to the order of $10^{-4}$ across a wide near-resonant detuning range. The method also scales effectively with the number of spectators. With three simultaneous spectators, the total leakage remains below the threshold relevant for surface code error correction. This approach eases the tension between dense frequency packing and high-fidelity gate operation, establishing dynamic Hamiltonian engineering as an essential tool for advancing fault-tolerant quantum computing.

Figures

Figures reproduced from arXiv: 2507.14531 by the authors.

Figure 1
Figure 1. FIG. 1. (a) Schematic representation of the three-qubit archi [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. FIG. 2. Numerical simulation of the leakage suppression [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. FIG. 3. Experimental validation of the dynamic leakage sup [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figures from the paper (1 more)
Figure 4
Figure 4. Figure 4: FIG. 4. (a) Schematic diagram of the 5 qubits system used to [PITH_FULL_IMAGE:figures/full_fig_p005_4.png]

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

41 extracted references · 34 canonical work pages

  1. [1]

    Wendin, Quantum information processing with su- perconducting circuits: A review, Rep

    G. Wendin, Quantum information processing with su- perconducting circuits: A review, Rep. Prog. Phys. 80, 106001 (2017)

    work page 2017

  2. [2]

    Krantz, M

    P. Krantz, M. Kjaergaard, F. Yan, T. P. Orlando, S. Gus- tavsson, and W. D. Oliver, A quantum engineer’s guide to superconducting qubits, Appl. Phys. Rev. 6, 021318 (2019)

    2019

  3. [3]

    Blais, A

    A. Blais, A. L. Grimsmo, S. M. Girvin, and A. Wallraff, Circuit quantum electrodynamics, Rev. Mod. Phys. 93, 025005 (2021)

    2021

  4. [4]

    Z. Li, P. Liu, P. Zhao, Z. Mi, H. Xu, X. Liang, T. Su, W. Sun, G. Xue, J.-N. Zhang, W. Liu, Y. Jin, and H. Yu, Error per single-qubit gate below 10-4 in a superconduct- ing qubit, npj Quantum Inf. 9, 111 (2023)

    work page 2023

  5. [5]

    D. A. Rower, L. Ding, H. Zhang, M. Hays, J. An, P. M. Harrington, I. T. Rosen, J. M. Gertler, T. M. Haz- ard, B. M. Niedzielski, M. E. Schwartz, S. Gustavsson, K. Serniak, J. A. Grover, and W. D. Oliver, Suppress- ing Counter-Rotating Errors for Fast Single-Qubit Gates with Fluxonium, Phys. Rev. Applied 10, 1 (2024)

    work page 2024

  6. [6]

    R. Li, K. Kubo, Y. Ho, Z. Yan, Y. Nakamura, and H. Goto, Realization of High-Fidelity CZ Gate Based on a Double-Transmon Coupler, Phys. Rev. X 14, 041050 (2024)

    work page 2024

  7. [7]

    N. J. Glaser, F. A. Roy, I. Tsitsilin, L. Koch, N. Bruck- moser, J. Schirk, J. H. Romeiro, G. B. P. Huber, F. Wall- ner, M. Singh, G. Krylov, A. Marx, L. S¨ odergren, C. M. F. Schneider, M. Werninghaus, et al. , Sensitivity- Adapted Closed-Loop Optimization for High-Fidelity Controlled-Z Gates in Superconducting Qubits (2024), arXiv:2412.17454 [quant-ph]

    arXiv 2024

  8. [8]

    Z. Zhou, A. Ji, and Y. Ding, Characterization and Miti- gation of Crosstalk in Quantum Error Correction (2025), arXiv:2503.04642 [quant-ph]

    arXiv 2025

Show all 41 references
  1. [9]

    Parrado-Rodr ´ ıguez, C

    P. Parrado-Rodr ´ ıguez, C. Ryan-Anderson, A. Bermudez, and M. M¨ uller, Crosstalk suppression for fault-tolerant quantum error correction with trapped ions, Quantum 5, 487 (2021)

    2021

  2. [10]

    C. Fang, Y. Wang, S. Huang, K. R. Brown, and J. Kim, Crosstalk Suppression in Individually Addressed Two- Qubit Gates in a Trapped-Ion Quantum Computer, Phys. Rev. Lett. 129, 240504 (2022)

    2022

  3. [11]

    Levine, A

    H. Levine, A. Keesling, G. Semeghini, A. Omran, T. T. Wang, S. Ebadi, H. Bernien, M. Greiner, V. Vuleti´ c, H. Pichler, and M. D. Lukin, Parallel Implementation of High-Fidelity Multiqubit Gates with Neutral Atoms, Phys. Rev. Lett. 123, 1 (2019)

    2019

  4. [12]

    Ketterer and T

    A. Ketterer and T. Wellens, Characterizing Crosstalk of 6 Superconducting Transmon Processors, Phys. Rev. Ap- plied 20, 1 (2023)

    2023

  5. [13]

    X. Y. Yang, H. F. Zhang, L. Du, H. R. Tao, L. L. Guo, T. L. Wang, Z. L. Jia, W. C. Kong, Z. Y. Chen, P. Duan, and G. P. Guo, Fast, universal scheme for calibrating microwave crosstalk in superconducting circuits, Appl. Phys. Lett. 125, 044001 (2024)

    2024

  6. [14]

    F. Yan, P. Krantz, Y. Sung, M. Kjaergaard, D. L. Campbell, T. P. Orlando, S. Gustavsson, and W. D. Oliver, Tunable Coupling Scheme for Implementing High-Fidelity Two-Qubit Gates, Phys. Rev. Applied 10, 1 (2018)

    2018

  7. [15]

    Z. Ni, S. Li, L. Zhang, J. Chu, J. Niu, T. Yan, X. Deng, L. Hu, J. Li, Y. Zhong, S. Liu, F. Yan, Y. Xu, and D. Yu, Scalable Method for Eliminating Residual ZZ Interaction between Superconducting Qubits, Phys. Rev. Lett. 129, 040502 (2022)

    2022

  8. [16]

    P. Zhao, K. Linghu, Z. Li, P. Xu, R. Wang, G. Xue, Y. Jin, and H. Yu, Quantum Crosstalk Analysis for Simultaneous Gate Operations on Superconducting Qubits, PRX Quantum 3, 1 (2022)

    2022

  9. [17]

    Acharya, I

    R. Acharya, I. Aleiner, R. Allen, T. I. Andersen, M. Ans- mann, F. Arute, K. Arya, A. Asfaw, J. Atalaya, R. Bab- bush, D. Bacon, J. C. Bardin, J. Basso, A. Bengtsson, S. Boixo, et al. , Suppressing quantum errors by scaling a surface code logical qubit, Nature 614, 676 (2023)

    2023

  10. [18]

    Krinner, S

    S. Krinner, S. Lazar, A. Remm, C. K. Andersen, N. Lacroix, G. J. Norris, C. Hellings, M. Gabureac, C. Eichler, and A. Wallraff, Benchmarking coherent er- rors in controlled-phase gates due to spectator qubits, Phys. Rev. Applied 14, 1 (2020)

    2020

  11. [19]

    T. Q. Cai, X. Y. Han, Y. K. Wu, Y. L. Ma, J. H. Wang, Z. L. Wang, H. Y. Zhang, H. Y. Wang, Y. P. Song, and L. M. Duan, Impact of Spectators on a Two-Qubit Gate in a Tunable Coupling Superconducting Circuit, Phys. Rev. Lett. 127, 060505 (2021)

    2021

  12. [20]

    J. B. Hertzberg, E. J. Zhang, S. Rosenblatt, E. Mage- san, J. A. Smolin, J. B. Yau, V. P. Adiga, M. Sandberg, M. Brink, J. M. Chow, and J. S. Orcutt, Laser-annealing Josephson junctions for yielding scaled-up superconduct- ing quantum processors, npj Quantum Inf. 7, 1 (2021)

    2021

  13. [21]

    P. V. Klimov, A. Bengtsson, C. Quintana, A. Bourassa, S. Hong, A. Dunsworth, K. J. Satzinger, W. P. Liv- ingston, V. Sivak, M. Y. Niu, T. I. Andersen, Y. Zhang, D. Chik, Z. Chen, C. Neill, et al. , Optimizing quantum gates towards the scale of logical qubits, Nat. Commun. 15, ...

    2024

  14. [22]

    B.-H. Lu, P. Wang, Z.-Y. Chen, H.-Y. Liu, T.-P. Sun, P. Duan, Y.-C. Wu, and G.-P. Guo, CAMEL: Physically Inspired Crosstalk-Aware Mapping and Gate Scheduling for Frequency-Tunable Quantum Chips, IEEE Transac- tions on Computer-Aided Design of Integrated Circuits and Systems 44...

    2025

  15. [23]

    D. M. Zajac, J. Stehlik, D. L. Underwood, T. Phung, J. Blair, S. Carnevale, D. Klaus, G. A. Keefe, A. Carniol, M. Kumph, M. Steffen, and O. E. Dial, Specta- tor Errors in Tunable Coupling Architectures (2021), arXiv:2108.11221 [quant-ph]

    2021 arXiv

  16. [24]

    K. C. Miao, M. McEwen, J. Atalaya, D. Kafri, L. P. Pryadko, A. Bengtsson, A. Opremcak, K. J. Satzinger, Z. Chen, P. V. Klimov, C. Quintana, R. Acharya, K. An- derson, M. Ansmann, F. Arute, et al. , Overcoming leak- age in quantum error correction, Nat. Phys. 19, 1780 (2023)

    2023

  17. [25]

    Marshall and D

    J. Marshall and D. Kafri, Incoherent Approximation of Leakage in Quantum Error Correction, Phys. Rev. Ap- plied 23, 054025 (2025)

    2025

  18. [26]

    Vall´ es-Sanclemente, T

    S. Vall´ es-Sanclemente, T. H. F. Vroomans, T. R. van Ab- swoude, F. Brulleman, T. Stavenga, S. L. M. van der Meer, Y. Xin, A. Lawrence, V. Singh, M. A. Rol, and L. DiCarlo, Optimizing the frequency positioning of tunable couplers in a circuit QED processor to mit- igate spect...

    2025 arXiv

  19. [27]

    F. W. Strauch, P. R. Johnson, A. J. Dragt, C. J. Lobb, J. R. Anderson, and F. C. Wellstood, Quantum logic gates for coupled superconducting phase qubits, Phys. Rev. Lett. 91, 2 (2003)

    2003

  20. [28]

    Dicarlo, J

    L. Dicarlo, J. M. Chow, J. M. Gambetta, L. S. Bishop, B. R. Johnson, D. I. Schuster, J. Majer, A. Blais, L. Frun- zio, S. M. Girvin, and R. J. Schoelkopf, Demonstration of two-qubit algorithms with a superconducting quantum processor, Nature 460, 240 (2009)

    2009

  21. [29]

    Barends, C

    R. Barends, C. M. Quintana, A. G. Petukhov, Y. Chen, D. Kafri, K. Kechedzhi, R. Collins, O. Naaman, S. Boixo, F. Arute, K. Arya, D. Buell, B. Burkett, Z. Chen, B. Chiaro, et al. , Diabatic Gates for Frequency-Tunable Superconducting Qubits, Phys. Rev. Lett. 123, 210501 (2019)

    2019

  22. [30]

    Lu, Q.-S

    B.-H. Lu, Q.-S. Li, P. Wang, Z.-Y. Chen, Y.-C. Wu, and G.-P. Guo, Neural Network-Based Frequency Optimiza- tion for Superconducting Quantum Chips, Chin. Phys. Lett. 42, 030204 (2025)

    2025

  23. [31]

    Arute, K

    F. Arute, K. Arya, R. Babbush, D. Bacon, J. C. Bardin, R. Barends, A. Bengtsson, S. Boixo, M. Broughton, B. B. Buckley, D. A. Buell, B. Burkett, N. Bushnell, Y. Chen, Z. Chen, et al. , Observation of separated dynamics of charge and spin in the Fermi-Hubbard model (2020), arXi...

    2020 arXiv

  24. [32]

    J. A. Gross, ´E. Genois, D. M. Debroy, Y. Zhang, W. Mruczkiewicz, Z.-P. Cian, and Z. Jiang, Character- izing coherent errors using matrix-element amplification, npj Quantum Inf. 10, 123 (2024)

    2024

  25. [33]

    Spectator Leakage Elimination in CZ Ga tes via Tunable Coupler Interference on a Superconducting Quantum Processor

    C. Neill, P. Roushan, K. Kechedzhi, S. Boixo, S. V. Isakov, V. Smelyanskiy, A. Megrant, B. Chiaro, A. Dunsworth, K. Arya, R. Barends, B. Burkett, Y. Chen, Z. Chen, A. Fowler, et al. , A blueprint for demonstrating quantum supremacy with superconduct- ing qubits, Science 360, 1...

    2018

  26. [34]

    Bravyi, D

    S. Bravyi, D. P. Divincenzo, and D. Loss, Schrieffer-Wolff transform ation for quantum many-body systems, Annals of Physics 326, 2793 (2011)

    2011

  27. [35]

    Y. Dang, S. Dhamapurkar, X. Zhu, Z. Zhou, H. Guan, and X. Deng, We aving complex graph on simple low-dimensional qubit lattices, in 2024 International Conference on Quantum Communications, N etworking, and Computing (QCNC) (2024) pp. 111–118

    2024

  28. [36]

    P. Duan, Z. Jia, C. Zhang, L. Du, H. Tao, X. Yang, L. Guo, Y. Che n, H. Zhang, Z. Peng, W. Kong, H.-O. Li, G. Cao, and G.-P. Guo, Broadband flux-pumped Josephson parametric ampl ifier with an on-chip coplanar waveguide impedance transformer, Appl. Phys. Express 14, 042011 (2021)

    2021

  29. [37]

    P. V. Klimov, A. Bengtsson, C. Quintana, A. Bourassa, S. Ho ng, A. Dunsworth, K. J. Satzinger, W. P. Livingston, V. Sivak, M. Y. Niu, T. I. Andersen, Y. Zhang, D. Chik, Z. Chen, C. Neill, et al. , Optimizing quantum gates towards the scale of logical qubits, Nat. Commun. 15, 2...

    2024

  30. [38]

    Zhang, T.-L

    C. Zhang, T.-L. Wang, L.-L. Guo, X.-Y. Yang, X.-X. Yang, P . Duan, Z.-L. Jia, W.-C. Kong, and G.-P. Guo, Characterization of tunable coupler without a dedicated readout resonator in su perconducting circuits, Appl. Phys. Lett. 122, 024001 (2023)

    2023

  31. [39]

    Y. Sung, L. Ding, J. Braum¨ uller, A. Veps¨ al¨ ainen, B. Kanna n, M. Kjaergaard, A. Greene, G. O. Samach, C. McNally, D. Kim, A. Melville, B. M. Niedzielski, M. E. Schwartz, J. L. Yod er, T. P. Orlando, et al. , Realization of High-Fidelity CZ and ZZ -Free iSW AP Gates with a...

    2021

  32. [40]

    C. J. Wood and J. M. Gambetta, Quantification and characteri zation of leakage errors, Phys. Rev. A 97, 32306 (2018)

    2018

  33. [41]

    Barends, C

    R. Barends, C. M. Quintana, A. G. Petukhov, Y. Chen, D. Kafri, K . Kechedzhi, R. Collins, O. Naaman, S. Boixo, F. Arute, K. Arya, D. Buell, B. Burkett, Z. Chen, B. Chiaro, et al. , Diabatic Gates for Frequency-Tunable Superconducting Qubits , Phys. Rev. Lett. 123, 210501 (2019)

    2019

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.