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Calibration for single-qubit gates using robust phase estimation

William Kirby, Shelby Kimmel

Bulletin of the American Physical SocietyMar 8, 20190 citations

Robust phase estimation for two-qubit gates

Benjamin Marinoff, Joshua Combes, Nicholas C. Rubin +1 more

Bulletin of the American Physical SocietyMar 17, 20210 citations

2019: A Hilbert Space Odyssey into the characterization of two-qubit gates using phase estimation

Kyle Gulshen, Amy E. Brown, Alexa Staley +2 more

Bulletin of the American Physical SocietyMar 8, 20190 citations

Automatic Two-qubit Gate Calibration with QubiC

Yilun Xu, Gang Huang, Ravi Naik +5 more

Bulletin of the American Physical SocietyMar 18, 20211 citation

Heisenberg-limited calibration of entangling gates with robust phase estimation

Kenneth Rudinger, J. P. Marceaux, Akel Hashim +3 more

The calibration of high-quality two-qubit entangling gates is an essential component in engineering large-scale, fault-tolerant quantum computers. However, many standard calibration techniques are based on randomized circuits that are only quadratically sensitive to calibration errors. As a result, these approaches are inefficient, requiring many experimental shots to achieve acceptable performance. In this work, we demonstrate that robust phase estimation can enable high-precision, Heisenberg-limited estimates of coherent errors in multi-qubit gates. Equipped with an efficient estimator, the calibration problem may be reduced to a simple optimization loop that minimizes the estimated coherent error. We experimentally demonstrate our calibration protocols by improving the operation of a two-qubit controlled-Z gate on a superconducting processor, and we validate the improved performance with gate set tomography. Our methods are applicable to gates in other quantum hardware platforms such as ion traps and neutral atoms, and on other multi-qubit gates, such as CNOT or iSWAP.The calibration of high-quality two-qubit entangling gates is an essential component in engineering large-scale, fault-tolerant quantum computers. However, many standard calibration techniques are based on randomized circuits that are only quadratically sensitive to calibration errors. As a result, these approaches are inefficient, requiring many experimental shots to achieve acceptable performance. In this work, we demonstrate that robust phase estimation can enable high-precision, Heisenberg-limited estimates of coherent errors in multi-qubit gates. Equipped with an efficient estimator, the calibration problem may be reduced to a simple optimization loop that minimizes the estimated coherent error. We experimentally demonstrate our calibration protocols by improving the operation of a two-qubit controlled-Z gate on a superconducting processor, and we validate the improved performance with gate set tomography. Our methods are applicable to gates in other quantum hardware platforms such as ion traps and neutral atoms, and on other multi-qubit gates, such as CNOT or iSWAP.

arXiv:2502.06698Feb 10, 20250 citations

Testing the robustness of robust phase estimation

Adam M. Meier, Jan‐Karl Burkhardt, Brian J. McMahon +1 more

The robust phase estimation (RPE) protocol was designed to be an efficient and robust way to calibrate quantum operations. The robustness of RPE refers to its ability to estimate a single parameter, usually gate amplitude, even when other parameters are poorly calibrated or when the gate experiences significant errors. Here we demonstrate the robustness of RPE to errors that affect initialization, measurement, and gates. In each case, the error threshold at which RPE begins to fail matches quantitatively with theoretical bounds. We conclude that RPE is an effective and reliable tool for calibration of one-qubit rotations and that it is particularly useful for automated calibration routines and sensor tasks.The robust phase estimation (RPE) protocol was designed to be an efficient and robust way to calibrate quantum operations. The robustness of RPE refers to its ability to estimate a single parameter, usually gate amplitude, even when other parameters are poorly calibrated or when the gate experiences significant errors. Here we demonstrate the robustness of RPE to errors that affect initialization, measurement, and gates. In each case, the error threshold at which RPE begins to fail matches quantitatively with theoretical bounds. We conclude that RPE is an effective and reliable tool for calibration of one-qubit rotations and that it is particularly useful for automated calibration routines and sensor tasks.

arXiv:1907.11766Physical Review ANov 11, 20199 citations

Calibrating two-qubit gates via robust phase estimation

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