Generalized Cycle Benchmarking Algorithm for Characterizing Midcircuit Measurements

Journal Article · Wed Jan 15 00:00:00 EST 2025 · PRX Quantum

DOI:https://doi.org/10.1103/PRXQuantum.6.010310· OSTI ID:2500932

Zhang, Zhihan; Chen, Senrui; Liu, Yunchao; Jiang, Liang

Midcircuit measurements (MCMs) are crucial ingredients in the development of fault-tolerant quantum computation. While there have been rapid experimental progresses in realizing MCMs, a systematic method for characterizing noisy MCMs is still under exploration. In this work, we develop a cycle benchmarking (CB)-type algorithm to characterize noisy MCMs. The key idea is to use a joint Fourier transform on the classical and quantum registers and then estimate parameters in the Fourier space, analogous to Pauli fidelities used in CB-type algorithms for characterizing the Pauli-noise channel of Clifford gates. Furthermore, we develop a theory of the noise learnability of MCMs, which determines what information can be learned about the noise model (in the presence of state preparation and terminating measurement noise) and what cannot, which shows that all learnable information can be learned using our algorithm. As an application, we show how to use the learned information to test the independence between measurement noise and state-preparation noise in an MCM. Finally, we conduct numerical simulations to illustrate the practical applicability of the algorithm. Similar to other CB-type algorithms, we expect the algorithm to provide a useful toolkit that is of experimental interest. Published by the American Physical Society 2025

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0024124; 2311733; W911NF-21-1-0325; FA9550-19-1-0399; FA9550-21-1-0209; FA9550-23-1-0338
• OSTI ID: 2500932
• Journal Information: PRX Quantum, Journal Name: PRX Quantum Vol. 6 Journal Issue: 1; ISSN 2691-3399
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English