Erasure Qubits Based on Fluxonium Circuits – Part 2

Erasure qubits can be appealing in certain quantum error correction codes, as they can significantly increase the error threshold and the code distance by converting the dominating errors in the system to detectable erasure errors. In superconducting qubit architectures, erasure qubits based on transmons and high-Q cavities have been demonstrated to have long coherence and high gate fidelities. In this presentation, we report designs of erasure qubits based on fluxonium circuits. We realize mid-circuit erasure checks without any ancilla systems, which shouldn't perturb the logical qubit subspace. We analyze the error that comes from false erasure checks and the dephasing induced by erasure checks. We demonstrate that fluxonium qubits can be useful building blocks of an erasure qubit, particularly due to their long coherence times. Part 2 will focus on early experimental data.