Outline of Research and Development Proposals
In order to generate GKP qubits, which are expected to have the lowest tolerance threshold, realization of higher-order nonlinear optical processes is required. In this project, we aim to achieve this in a measurement-induced manner using a superconductor photon number discriminator. Specifically, we generate a quantum entanglement by using squeezed light and a beam splitter, and detect a given number of photons in a part of the entanglement using a superconductior photon number discriminator. Here, the GKP qubit is generated at the moment when a given number of photons are detected, so in order to use it at any given time, a quantum memory is also needed. We have already started to develop a photon number discriminator, and aim to achieve an operating speed equivalent to an optical quantum computer clock frequency of 1 GHz. We have also succeeded in developing an all-optical quantum memory to some extent, and are aiming to improve its performance.
