Towards experimental realization of a non-degenerate noise-resilient superconducting qubit

The recently proposed “harmonium” circuit [1] has been theoretically shown to realize a periodic potential with two non-degenerate minima, supporting long-lived, disjoint qubit states localized in separate potential wells. In addition, the depth of the two minima, much larger than the circuit’s charging energy, and their near-symmetry provide simultaneous protection against dephasing. Finally, this protection is expected to be maintained while allowing standard dispersive readout, single-qubit gates, and two-qubit gates. Building on the proposed architecture, which is compatible with current fabrication technology, we present recent advances in the implementation of the harmonium circuit. We describe the qubit design and discuss our progress towards fabricating and measuring initial harmonium qubits.

[1] M. Hays et al., arXiv:2502.15459 (2025)