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A precise CNOT gate in the presence of large fabrication induced variations of the exchange interaction strength

M. J. Testolin·C. D. Hill·C. J. Wellard·L. C. L. Hollenberg
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Abstract

We demonstrate how using two-qubit composite rotations a high fidelity controlled-NOT (CNOT) gate can be constructed, even when the strength of the interaction between qubits is not accurately known. We focus on the exchange interaction oscillation in silicon based solid-state architectures with a Heisenberg Hamiltonian. This method easily applies to a general two-qubit Hamiltonian. We show how the robust CNOT gate can achieve a very high fidelity when a single application of the composite rotations is combined with a modest level of Hamiltonian characterisation. Operating the robust CNOT gate in a suitably characterised system means concatenation of the composite pulse is unnecessary, hence reducing operation time, and ensuring the gate operates below the threshold required for fault-tolerant quantum computation.

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M. J. Testolin, C. D. Hill, C. J. Wellard, L. C. L. Hollenberg. 2007-01-23. A precise CNOT gate in the presence of large fabrication induced variations of the exchange interaction strength. https://doi.org/10.1103/physreva.76.012302

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