Small-scale quantum processor with Heavy-Fluxonium Qubit

Among the various platforms for quantum computation and information processing, superconducting qubits have been a promising candidate for fault-tolerant computation. In the past, multi-qubit processors have only used transmon qubit designs. However, transmon has a fundamental limitation, it sacrifices anharmonicity, a precious quantum resource. Transmon's weak anharmonicity leads to slower two-qubit gates making it prone to decoherence errors. It also limits the scalability of quantum processors, a direct consequence of restricted parameter space of operation, thus motivating us to look for alternatives. Recently, fluxonium qubit has emerged as a serious contender for building a superconducting quantum processor. Fluxonium qubits have the potential to excel over transmons due to their inherent advantages of high coherence times and higher anharmonicity. One of the crucial steps in building a fault-tolerant quantum processor is implementing high-fidelity single- and multi-qubit gates. In addition, it is also necessary to have a high-fidelity, quantum non-demolition (QND) readout. Here, we will discuss our implementation of a two-qubit fluxonium gate and experiments to characterize and optimize high-fidelity readout. We will also describe a multi-qubit architecture to build a small-scale quantum processor using fluxonium qubits.