Member of Chinese academy of sciences, China university of science and technology, professor guang-can guo leadership of the Chinese academy of sciences key laboratory of quantum information for the first time successfully developed silicon membrane quantum integrated chip. The laboratory Ren Xifeng team has made new progress in the study of quantum integrated optical chips, they and the modern optical instruments, zhejiang university professor of state key laboratory of wear zinc cooperation, for the first time in silicon photonic integrated chip using silicon nanometer optical waveguide intrinsic mode as the new dimension of quantum information coding, has realized the single photon states and quantum entanglement in the polarization, paths, waveguide mode coherence between the different degrees of freedom such as conversion, its interference visibility all more than 90%, for quantum optics, integrated chip photon multiple degrees of freedom of manipulation and transformation provides important experimental basis. Relevant results on June 20th, published in the journal nature communications [naturecommunications7, articlenumber11985 (2016)]. Paper tied for the first author is a Chinese PhD students at hkust Feng Lan days, Dr Erros zhiyuan zhang Ming and doctoral students of zhejiang university.

Compared with the free space optics, fiber optics, the integration of optical devices and system has smaller size, extensible, low power consumption, high stability, a lot of advantage. So in the field of classical optics and quantum information has received widespread attention. In quantum optics chip former research, people usually adopt the polarization degree of freedom, freedom or path is using different polarization or different paths to realize quantum information coding. Among them, the polarization encoding can only achieve two-dimensional quantum information process, cannot achieve higher dimensional coding, so obvious deficiencies in information capacity and security; Although path coding can achieve high dimensional quantum information process, but in order to prevent crosstalk between different path information, its path spacing generally larger, greatly restricted the quantum optical chips has promoted the integration and function extension.

Ren Xifeng team and collaborators eigen mode of multimode waveguides is presented in this paper for the first time as a new degree of freedom of coding quantum information. Use a support multiple mode of multimode waveguide is expected to achieve high dimensional quantum information coding. , for example, width is about 2.4 micron soi optical waveguide, can support the eight guide mode, corresponding to the eight photonic information coding. Orthogonal to each other between these patterns, in particular, effectively avoid the problem of information crosstalk. At the same time, also can be in the process of quantum information at the same time using multiple degrees of freedom of photons, which significantly increased information capacity. The researchers used a new silicon substrate mode converter and multiplex, polarization is implemented, arbitrary coherence between the degrees of freedom of the path and the waveguide mode conversion, single photon and two photon interference visibility are more than 90%, fully shows the integration of quantum optical chips in the possibility of manipulation of multiple degrees of freedom at the same time, in order to realize integration of quantum optical chips in high-dimensional laid the important foundation of quantum information process.

The research backed by the national natural science foundation, the Chinese academy of sciences, ministry of science and technology, ministry of education and Chinese university, zhejiang university.