Optimization of a solid-state electron spin qubit using gate set tomography. (13th October 2016)

• Record Type: Journal Article
• Authors: Dehollain, Juan P; Muhonen, Juha T; Blume-Kohout, Robin; Rudinger, Kenneth M; Gamble, John King; Nielsen, Erik; Laucht, Arne; Simmons, Stephanie; Kalra, Rachpon; Dzurak, Andrew S; Morello, Andrea
• Is Part Of: New journal of physics. Volume 18:Number 10(2016:Oct.)
• Publication Date: 2016-10-13
• Subjects: quantum computing -- silicon -- tomography; 03.65.Wj -- 03.67.Ac -- 03.67.Lx -- 07.05.Fb -- 85.35.Gv; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/18/10/103018
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: State of the art qubit systems are reaching the gate fidelities required for scalable quantum computation architectures. Further improvements in the fidelity of quantum gates demands characterization and benchmarking protocols that are efficient, reliable and extremely accurate. Ideally, a benchmarking protocol should also provide information on how to rectify residual errors. Gate set tomography (GST) is one such protocol designed to give detailed characterization of as-built qubits. We implemented GST on a high-fidelity electron-spin qubit confined by a single 31 P atom in 28 Si. The results reveal systematic errors that a randomized benchmarking analysis could measure but not identify, whereas GST indicated the need for improved calibration of the length of the control pulses. After introducing this modification, we measured a new benchmark average gate fidelity of 99.942 ( 8 ) %, an improvement on the previous value of 99.90 ( 2 ) % . Furthermore, GST revealed high levels of non-Markovian noise in the system, which will need to be understood and addressed when the qubit is used within a fault-tolerant quantum computation scheme.