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AllXY

This experiment performs an AllXY measurement to characterise quantum gate performance.

Description

AllXY1 is a gate tune-up sequence consisting of 21 circuits made up of combinations of \(\pi\)- and \(\frac{\pi}{2}\)-pulses. Each circuit is designed to test different aspects of the quantum gate performance and is sensitive to various types of error syndromes. These include (but are not limited to) miscalibrated readout, control, and DRAG pulse amplitudes, as well as unwanted detuning between the drive pulse frequency and the qubit's resonance frequency.

The ideal resulting states of the qubit create a staircase pattern where one only sees \(|0\rangle\), \(|1\rangle\), or an equal superposition of the two. In reality, various deviations from this ideal staircase pattern show up which qualitatively indicate different syndromes arising from various gate imperfections.

Experimental steps

  1. The qubit is prepared in the ground state \(|0\rangle\).

  2. AllXY sequences are applied for varying \(\pi\)- and \(\frac{\pi}{2}\)-pulse amplitudes and drive frequencies.

  3. The resonator transmission is measured and the \(I\) and \(Q\) signals are collected for each sequence, amplitude, and frequency.

Analysis steps

  1. The qubit populations are computed as a function of sequence, amplitude, and detuning (frequency). The readout discriminator is used to determine the qubit state.

  2. The resulting qubit population is plotted as a function of sequence, amplitude, and detuning.

  3. The plots are inspected to detect error syndromes based on deviation of sequence results from the ideal staircase pattern.

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  1. Matthew Reed. Entanglement and quantum error correction with superconducting qubits. 2013. arXiv:1311.6759. ↩