Efficient benchmarking of logical magic state

Oral-In-person

Abstract

High-fidelity logical magic states are a critical resource for fault-tolerant quantum computation, enabling non-Clifford logical operations through state injection. However, benchmarking these states presents significant challenges: one must estimate the infidelity $\epsilon$ with multiplicative precision, while many quantum error-correcting codes only permit Clifford operations to be implemented fault-tolerantly. Consequently, conventional state tomography requires $\sim1/\epsilon^2$ samples, making benchmarking impractical for high-fidelity states. In this work, we show that any benchmarking scheme measuring one copy of the magic state per round necessarily requires $\Omega(1/\epsilon^2)$ samples for single-qubit magic states. We then propose two approaches to overcome this limitation: (i) Bell measurements on two copies of the twirled state and (ii) single-copy schemes leveraging twirled multi-qubit magic states. Both benchmarking schemes utilize measurements with stabilizer states orthogonal to the ideal magic state, and we show that $O(1/\epsilon)$ sample complexity is achieved, which we prove to be optimal. Finally, we demonstrate the robustness of our protocols through numerical simulations under realistic noise models, confirming that their advantage persists even at moderate error rates currently achievable in state-of-the-art experiments.

Publication: Su-un Lee, Ming Yuan, Senrui Chen, Kento Tsubouchi, and Liang Jiang, Efficient benchmarking of logical magic state (2024), arXiv:2505.09687 [quant-ph].

Presenters

  • Su-un Lee

    • University of Chicago

Authors

  • Su-un Lee

    • University of Chicago
  • Ming Yuan

    • University of Colorado Boulder
  • Senrui Chen

    • University of Chicago
  • Kento Tsubouchi

    • The University of Tokyo
  • Liang Jiang

    • University of Chicago