Logical gates for protected superconducting qubits via tunable elements

Protected superconducting circuits rely on complex multinode circuits (e.g. the 0-π qubit) or non-standard circuit elements (e.g. the dualmon qubit) to achieve exponential suppression of both depolarisation and pure-dephasing. In regimes of extreme protection, conventional Rabi- or Raman-style driving is practically infeasible. We investigate the use of tunable circuit elements as a means to achieve logical gates on protected qubits, building on the earlier ideas of Brooks, Kitaev and Preskill (BKP) [1]. These tunable elements provide a means to break the approximate symmetries that define the encoded qubit, and enact logical operations. We pay particular attention to the performance of these gates when the control of the tunable circuit elements is imprecise.

[1] P Brooks, A Kitaev, and J Preskill. Protected gates for superconducting qubits. Physical Review A, 87(5), 2013.