The fluxonium is a type of superconducting qubit that uses a Josephson junction shunted by a large inductance (typically a chain of additional Josephson junctions) to create a qubit with favorable coherence properties and strong anharmonicity.
Why it matters. The transmon qubit, the most widely used superconducting qubit, achieves good coherence by operating in a regime where it is insensitive to charge noise, but this comes at the cost of low anharmonicity (the energy difference between computational and non-computational transitions is small). Low anharmonicity limits gate speed and introduces leakage errors.
The fluxonium addresses this by providing much larger anharmonicity while maintaining long coherence times, potentially enabling faster, higher-fidelity gates. It operates at lower frequencies than transmons (typically hundreds of MHz rather than several GHz), which changes the requirements for control and readout electronics. Fluxonium qubits are an active area of research and are being explored for fault-tolerant architectures.How it connects. The Qblox Cluster supports both baseband and RF frequency ranges needed for fluxonium control and readout. The QCM provides baseband control up to 400 MHz for driving fluxonium transitions, while the QRM handles baseband readout. For fluxonium designs that operate at higher frequencies, the full RF module lineup (QCM-RF II, QRM-RF, QRC) provides coverage up to 18.5 GHz. Learn more about the QCM.
