Quantum Design for Advanced Qubits

Abstract The past half century has witnessed the rapid development of integrated circuits from several to billions of electronic components, where a crucial enabling method was the electronic computer-aided design. Similarly, simulations of the quantum electrocircuits will play a key role in designing advanced quantum computers. While these simulations could be done classically on a small scale, the resources required for the classical simulations will grow exponentially with the complexity of the strongly-correlated quantum hardwares. Here, we demonstrate quantum computer-aided design of a new high-performance superconducting qubit based on variational quantum simulations. The discovered new qubits intrinsically have important features superior to the widely used transmons qubits, because the new design eliminates the charge noise but without sacrificing anharmonicity and thus has a larger anharmonicity than the transmons. The new qubit - which we call “plasmonium” - is compatible with the control technologies in the transmon, exhibits long coherence time, and can bring in a number of practical advantages, including shrinking physical sizes, improving gate and readout fidelity, reducing state leakage, and alleviating frequency crowding in multi-qubit devices.