Switching-free time-domain optical quantum computation with quantum teleportation

Abstract

Optical switches and rerouting networks are considered essential in optical quantum computers where they are used for injection and dejection of the necessary quantum states into an optical quantum computer. Practical optical switches and rerouting networks are, however, experimentally challenging as they must have extremely low loss, small switching time, high repetition rate, and minimum optical nonlinearity, requirements that are difficult to achieve simultaneously. In this paper, we present an optical quantum computation platform that does not require such optical switches. Our method is based on continuous-variable measurement-based quantum computation where, instead of the typical cluster states, we modify the structure of the quantum entanglement, so that the quantum teleportation protocol can be employed instead of optical switching and rerouting. The quantum entanglement structure in our architecture has additional modes that allow quantum states to be teleported in or out of the computation along the cluster state, a task that normally requires optical switches. We also outline how to combine our platform with Gottesman-Kitaev-Preskill encoding, the currently most promising encoding for a continuous-variable system.