Non-Clifford gate on optical qubits by nonlinear feedforward

Understand

In a continuous-variable optical system, the Gottesman-Kitaev-Preskill (GKP) qubit is a promising candidate for fault-tolerant quantum computation.

• To implement non-Clifford operations on GKP qubits, non-Gaussian operations are required.
• In this context, the implementation of a cubic phase gate by combining nonlinear feedforward with ancillary states has been widely researched.
• Recently, however, it is pointed out that the cubic phase gate is not the most suitable for non-Clifford operations on GKP qubits.