Towards scalable quantum computing based on silicon spin

Quantum computing (QC) is expected to extend the high performance computing roadmap [1]-[2] at the condition to be able to run a large number of errorless quantum operations, typically. over a billion. It is out of reach in actual physical systems because of the quantum decoherence. As a consequence, quantum error correction techniques, which utilize the idea of redundant encoding, have been introduced to cure for the errors [3]-[5]. In state-of-the-art codes, with error thresholds or fidelities around 10 ^-2 in Si spin qubits, it is expected that logical qubits will be made out of a few thousands or more of physical qubits [6], bringing the number of required physical qubits to perform relevant quantum calculations to at least a million.