Ultra-large-scale continuous-variable cluster states multiplexed in the time domain

Quantum computers promise ultrafast performance for certain tasks1. Experimentally appealing, measurement-based quantum computation2 requires an entangled resource called a cluster state3, with long computations requiring large cluster states. Previously, the largest cluster state consisted of eight photonic qubits4 or light modes5, and the largest multipartite entangled state of any sort involved 14 trapped ions6. These implementations involve quantum entities separated in space and, in general, each experimental apparatus is used only once. Here, we circumvent this inherent inefficiency by multiplexing light modes in the time domain. We deterministically generate and fully characterize a continuous-variable cluster state7,8 containing more than 10,000 entangled modes. This is, by three orders of magnitude, the largest entangled state created to date. The entangled modes are individually addressable wave packets of light in two beams. Furthermore, we present an efficient scheme for measurement-based quantum computation on this cluster state based on sequential applications of quantum teleportation.