Optical quantum information encoder based on selective quantum teleportation

In optical CV-MBQC (continuous-variable measurement-based quantum computing), large-scale quantum processors called cluster states have already been realized, making it one of the most promising quantum systems. To enable universal quantum computation using cluster states, non-classical quantum states must be encoded from the outside via optical switches. However, conventional switches based on Pockels cells and Mach-Zehnder interferometers require high-voltage switching, limiting their repetition rate to the kHz range. We proposed a new quantum encoding method based on selective teleportation, which offers a high-repetition rate and low-loss performance. However, this method requires dynamic and programmable feedforward (FF) switching within the quantum teleportation circuit. In this work, we demonstrate selective quantum teleportation as a proof of principle for FF switching. Using an FPGA board with 50 ns latency for digital processing, we implemented simultaneous switching of both the homodyne measurement basis and FF scheme. By using squeezed light as the input, we successfully observed selective output of squeezed light from either the input or the auxiliary EPR state. This approach lays the groundwork for practical cluster-state encoding in CV-MBQC.