Paper

Fast and high-fidelity state preparation and measurement in triple-quantum-dot spin qubits

Velunta, Roland, Keating, Tyler E, Jones, Aaron M, Eng, Kevin, Blumoff, Jacob Z, Barnes, David W, Raach, Kate, Lanza, Robert K, Andrews, Reed W, Ladd, Thaddeus D, Rakher, Matthew T, Jackson, Clayton A C, Euliss, Larken E, Kerckhoff, Joseph, Weinstein, Aaron J, Borselli, Matthew G, Brecht, Teresa L, Croke, Edward T, Pan, Andrew S, Fast, Jacob A, Thomas, Bryan J, Hunter, Andrew T

2022

Overview

We demonstrate rapid, high-fidelity state preparation and measurement in exchange-only Si/SiGe triple-quantum-dot qubits. Fast measurement integration (\\(980\\) ns) and initialization (\\(\\approx 300\\) ns) operations are performed with all-electrical, baseband control. We emphasize a leakage-sensitive joint initialization and measurement metric, developed in the context of exchange-only qubits but applicable more broadly, and report an infidelity of \\(2.5\\pm0.5\\times 10^{-3}\\). This result is enabled by a high-valley-splitting heterostructure, initialization at the 2-to-3 electron charge boundary, and careful assessment and mitigation of \\(T_1\\) during spin-to-charge conversion. The ultimate fidelity is limited by a number of comparably-important factors, and we identify clear paths towards further improved fidelity and speed. Along with an observed single-qubit randomized benchmarking error rate of \\(1.7\\times 10^{-3}\\), this work demonstrates initialization, control, and measurement of Si/SiGe triple-dot qubits at fidelities and durations which are promising for scalable quantum information processing.

• Publisher: Cornell University Library, arXiv.org
• Subject: Accuracy / Data processing / Heterostructures / Quantum dots / Quantum phenomena / Qubits (quantum computing) / Silicon germanides