This paper presents a study on the performance of superconducting qubits in achieving high-fidelity quantum gates necessary for fault-tolerant quantum computing using the surface code error correction scheme. The researchers demonstrate a universal set of logic gates in a superconducting multi-qubit processor, achieving an average single-qubit gate fidelity of 99.92% and a two-qubit gate fidelity up to 99.4%. These results place Josephson quantum computing at the fault-tolerant threshold for surface code error correction. The quantum processor consists of five qubits arranged in a linear array with nearest-neighbour coupling. The researchers construct a five-qubit Greenberger-Horne-Zeilinger (GHZ) state using the complete circuit and full set of gates, demonstrating the ability to create complex quantum states with high fidelity. The high fidelity performance is achieved through a combination of highly coherent qubits, a straightforward interconnection architecture, and a novel implementation of the two-qubit controlled-phase (CZ) entangling gate. The CZ gate uses a fast but adiabatic frequency tuning of the qubits, which is easily adjusted yet minimises decoherence and leakage from the computational basis. The researchers also show that the quantum processor is modular, allowing for the integration of more qubits in the circuit. The results demonstrate that Josephson quantum computing is a high-fidelity technology with a clear path to scaling up to large-scale, fault-tolerant quantum circuits. The study also includes detailed analysis of the error mechanisms in the CZ gate, including 2-state leakage, decoherence, and control error. The researchers find that the CZ gate fidelity is limited by these three error mechanisms, with decoherence being the largest contributor. They also show that the quantum processor can be used to generate complex quantum states with high fidelity, demonstrating the potential for more intricate algorithms on this multi-purpose quantum processor. The results highlight the potential of superconducting qubits for fault-tolerant quantum computing.This paper presents a study on the performance of superconducting qubits in achieving high-fidelity quantum gates necessary for fault-tolerant quantum computing using the surface code error correction scheme. The researchers demonstrate a universal set of logic gates in a superconducting multi-qubit processor, achieving an average single-qubit gate fidelity of 99.92% and a two-qubit gate fidelity up to 99.4%. These results place Josephson quantum computing at the fault-tolerant threshold for surface code error correction. The quantum processor consists of five qubits arranged in a linear array with nearest-neighbour coupling. The researchers construct a five-qubit Greenberger-Horne-Zeilinger (GHZ) state using the complete circuit and full set of gates, demonstrating the ability to create complex quantum states with high fidelity. The high fidelity performance is achieved through a combination of highly coherent qubits, a straightforward interconnection architecture, and a novel implementation of the two-qubit controlled-phase (CZ) entangling gate. The CZ gate uses a fast but adiabatic frequency tuning of the qubits, which is easily adjusted yet minimises decoherence and leakage from the computational basis. The researchers also show that the quantum processor is modular, allowing for the integration of more qubits in the circuit. The results demonstrate that Josephson quantum computing is a high-fidelity technology with a clear path to scaling up to large-scale, fault-tolerant quantum circuits. The study also includes detailed analysis of the error mechanisms in the CZ gate, including 2-state leakage, decoherence, and control error. The researchers find that the CZ gate fidelity is limited by these three error mechanisms, with decoherence being the largest contributor. They also show that the quantum processor can be used to generate complex quantum states with high fidelity, demonstrating the potential for more intricate algorithms on this multi-purpose quantum processor. The results highlight the potential of superconducting qubits for fault-tolerant quantum computing.