2022/08/24 by Bo Sun, Sun, Bo, T. Brecht +43 · 3 citations
Physics and Astronomy · Engineering · #Quantum and electron transport phenomena #Advanced Electrical Measurement Techniques #Analog and Mixed-Signal Circuit Design
paper · pdf · doi:10.48550/arxiv.2208.11784
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 5×10-5. This sequence maintains a quantum state for roughly 18,000 exchange pulses, extending the qubit coherence from T2^*=2~μs to T2 = 720~μs. 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.