Fig. 6: Implementation of the CCPhase Gate with three neighboring logical qubits.
The gate operation consists of two steps. In each step, a CZ gate is applied to the first two qubits in the x = 1 row while alternately enabling ZZ interactions V2 and − V2 between the latter two qubits. This ensures zero phase accumulation for \({| 1;1;0\rangle }_{L}\), \({| 1;0;1\rangle }_{L}\), and \({| 0;1;1\rangle }_{L}\), while a nonzero phase is accumulated exclusively on \({| 1;1;1\rangle }_{L}\).
