Right-sizing fluxonium against charge noise

Abstract

We analyze the charge-noise induced coherence time $T_2$ of the fluxonium qubit as a function of the number of array junctions in the device, $N$. The pure dephasing rate decreases with $N$, but we find that the relaxation rate increases, so $T_2$ achieves an optimum as a function of $N$. This optimum can be much smaller than the number typically chosen in experiments, yielding a route to improved fluxonium coherence and simplified device fabrication at the same time.

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• High-Fidelity, Frequency-Flexible Two-Qubit Fluxonium Gates with a Transmon Coupler
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• Geometric superinductance qubits: Controlling phase delocalization across a single Josephson junction
• Spin-boson quantum phase transition in multilevel superconducting qubits
• Fractional Josephson effect versus fractional charge in superconducting-normal metal hybrid circuits
• Direct detection of down-converted photons spontaneously produced at a single Josephson junction
• Variational tight-binding method for simulating large superconducting circuits
• Dephasing in Fluxonium Qubits from Coherent Quantum Phase Slips
• Charge quantization and detector resolution
• The quartic Blochnium: an anharmonic quasicharge superconducting qubit
• Counting interacting electrons in one dimension