Reducing leakage of single-qubit gates for superconducting quantum processors using analytical control pulse envelopes

• URL: http://arxiv.org/abs/2402.17757v1
• Date: Tue, 27 Feb 2024 18:48:08 GMT
• Title: Reducing leakage of single-qubit gates for superconducting quantum processors using analytical control pulse envelopes
• Authors: Eric Hyypp\"a, Antti Veps\"al\"ainen, Miha Papi\v{c}, Chun Fai Chan, Sinan Inel, Alessandro Landra, Wei Liu, J\"urgen Luus, Fabian Marxer, Caspar Ockeloen-Korppi, Sebastian Orbell, Brian Tarasinski, and Johannes Heinsoo
• Abstract summary: Fast logic gates lead to increased leakage errors in superconducting quantum processors based on qubits with low anharmonicity, such as transmons. We propose and experimentally demonstrate two new analytical methods, Fourier ansatz spectrum tuning derivative removal by adiabatic gate (FAST DRAG) and higher-derivative (HD) DRAG, to reduce leakage errors.
• Score: 32.40219976663139
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Improving the speed and fidelity of quantum logic gates is essential to reach quantum advantage with future quantum computers. However, fast logic gates lead to increased leakage errors in superconducting quantum processors based on qubits with low anharmonicity, such as transmons. To reduce leakage errors, we propose and experimentally demonstrate two new analytical methods, Fourier ansatz spectrum tuning derivative removal by adiabatic gate (FAST DRAG) and higher-derivative (HD) DRAG, both of which enable shaping single-qubit control pulses in the frequency domain to achieve stronger suppression of leakage transitions compared to previously demonstrated pulse shapes. Using the new methods to suppress the $ef$-transition of a transmon qubit with an anharmonicity of -212 MHz, we implement $R_X(\pi/2)$-gates with a leakage error below $3.0 \times 10^{-5}$ down to a gate duration of 6.25 ns, which corresponds to a 20-fold reduction in leakage compared to a conventional Cosine DRAG pulse. Employing the FAST DRAG method, we further achieve an error per gate of $(1.56 \pm 0.07)\times 10^{-4}$ at a 7.9-ns gate duration, outperforming conventional pulse shapes both in terms of error and gate speed. Furthermore, we study error-amplifying measurements for the characterization of temporal microwave control pulse distortions, and demonstrate that non-Markovian coherent errors caused by such distortions may be a significant source of error for sub-10-ns single-qubit gates unless corrected using predistortion.

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