Stroboscopically robust gates for capacitively coupled singlet-triplet qubits

Abstract

Recent work on Ising-coupled double-quantum-dot spin qubits in GaAs with voltage-controlled exchange interaction has shown improved two-qubit gate fidelities from the application of oscillating exchange along with a strong magnetic field gradient between adjacent dots [npj Quantum Inf. 3, 3 (2017)10.1038/s41534-016-0003-1]. By examining how noise propagates in the time-evolution operator of the system, we find an optimal set of parameters that provide passive stroboscopic circumvention of errors in two-qubit gates to first order. We predict over 99% two-qubit gate fidelities in the presence of quasistatic and 1/f noise, which is an order-of-magnitude improvement over the typical unoptimized implementation.