Superconducting qubits designed to exhibit protection from noise have recently received attention in the search for a qubit with coherence times that could exceed those of current state-of-the-art qubits. The current-mirror circuit has long been proposed as such a protected qubit. Based on an effective model capturing the low-energy excitations of the circuit, we present a simulation of spectral properties using density matrix renormalization group (DMRG) methods. Coherence times for the current mirror are predicted to exceed 1 ms, about an order of magnitude greater than those of industry-standard transmon qubits.

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