Integrated Quantum Photonics allows the routing and control of single particles of light with intrinsically high stability and precision. However to date it has been limited to small-scale demonstrations in which only a small number of components are integrated on a chip. It is thus in high demand to scale up the integrated photonic circuits and increase the complexity and computational power of modern quantum information processing technologies that would enable many revolutionary applications. In fact, coherently and precisely controlling large quantum devices and complex multidimensional entanglement systems has been a challenging task owing to the complex interactions of correlated particles in large quantum systems.
In an international research effort led by scientists from the University of Bristol’s Quantum Engineering Technology Labs, we demonstrated the first ever large-scale integrated quantum photonic circuit, which can generate, control and analyze high-dimensional entanglement with unprecedented high precision and generality. A programmable bipartite path-encoded multidimensional entangled system with dimension up to 15×15 was demonstrated, where each photon exists over 15 optical paths at the same time and the two photons are entangled with each other there. This multidimensional entanglement system is achieved by scaling up the silicon-photonics quantum circuits via a single chip integration of 550 optical components including 16 identical photon-pair sources, 93 optical phase-shifters, 122 beam-splitters, among other optical elements. The quantum chip was realised using a scalable silicon photonics technology, similar to today’s electronic circuits, which would provide a path to manufacture massive components for the realization of an optical quantum computer. The work was a joint effort of the Peking University, the Technical University of Denmark, ICFO, the Max Planck Institute of Quantum Optics, the Polish Academy of Sciences (PAS) and the University of Copenhagen.