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

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.

9 pages, 8 figures

References in corpus (4)

• Tackling Systematic Errors in Quantum Logic Gates with Composite Rotations
• Robust Ising Gates for Practical Quantum Computation
• Robust CNOT gates from almost any interaction
• Precision characterisation of two-qubit Hamiltonians via entanglement mapping

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• Fidelity Between Unitary Operators and the Generation of Gates Robust Against Off-Resonance Perturbations
• Quantum information processing in a spin-bus system of coupled chains
• On Binomial Summations and a Generalised Quantum SWAP Gate