Achieving A High Fidelity Controlled-NOT Gate Between A Pair Of Exchanged-Coupled Silicon Double-Quantum-Dot Hybrid Qubits*

It has been shown that operating qubits by varying exchange couplings while operating at sweet spots against detuning noise can improve gate fidelities. For double-quantum-dot hybrid qubits, this requires keeping the system in the large-detuning regime where dephasing is greatly suppressed. Here we show that, in a pair of exchange-coupled double-quantum-dot hybrid qubits, it is possible to exploit the large-detuning regime to achieve a sizeable exchange interaction between the qubits while suppressing leakage and dephasing, yielding a high-fidelity controlled phase gate with a gate time less than 1 ns. We find that the fidelity of a CNOT gate can be above 99.9%, in the presence of charge noise typical for semiconductor devices.