Full-permutation dynamical decoupling in triple-quantum-dot spin qubits

• Published in: arXiv.org 2022-09
• Main Authors: Sun, Bo, Brecht, Teresa, Fong, Bryan, Moonmoon Akmal, Blumoff, Jacob Z, Cain, Tyler A, Carter, Faustin W, Finestone, Dylan H, Fireman, Micha N, Ha, Wonill, Hatke, Anthony T, Hickey, Ryan M, Jackson, Clayton A C, Jenkins, Ian, Jones, Aaron M, Pan, Andrew, Ward, Daniel R, Weinstein, Aaron J, Whiteley, Samuel J, Williams, Parker, Borselli, Matthew G, Rakher, Matthew T, Ladd, Thaddeus D
• Format: Article
• Language: English
• Subjects: Decoupling method; Error analysis; Exchanging; Frequency spectrum; Leakage; Noise spectra; Permutations; Quantum dots; Qubits (quantum computing)
• ISSN: 2331-8422

Dynamical decoupling of spin qubits in silicon can enhance fidelity and be used to extract the frequency spectra of noise processes. We demonstrate a full-permutation dynamical decoupling technique that cyclically exchanges the spins in a triple-dot qubit. This sequence not only suppresses both low frequency charge-noise- and magnetic-noise-induced errors; it also refocuses leakage errors to first order, which is particularly interesting for encoded exchange-only qubits. For a specific construction, which we call NZ1y, the qubit is isolated from error sources to such a degree that we measure a remarkable exchange pulse error of \(5\times10^{-5}\). This sequence maintains a quantum state for roughly 18,000 exchange pulses, extending the qubit coherence from \(T_2^*=2~\mu\)s to \(T_2 = 720~\mu\)s. We experimentally validate an error model that includes \(1/f\) charge noise and \(1/f\) magnetic noise in two ways: by direct exchange-qubit simulation, and by integration of the assumed noise spectra with derived filter functions, both of which reproduce the measured error and leakage with respect to changing the repetition rate.