Optica 5, 193–198 (2018)

A six-photon quantum processor has been used to perform topological data analysis in a proof-of-principle experiment. Built by scientists in China and Australia, the processor, which makes use of three pairs of entangled photons generated in beta barium borate crystals, was programmed with a quantum algorithm that calculates the Betti numbers of data points. Betti numbers are important metrics used in topological analysis of datasets and can help extract useful information about the underlying structure of noisy or incomplete data. In this case, the algorithm was applied to a dataset of three data points. While the current demonstration is only performed with a small-scale quantum processor and a small number of data points, the research team believe that with a larger processor employing more qubits, the scheme could be extended to analysis of much larger datasets.