A polarization-irrelevant broadband waveguide beam splitter comprises at least one cross coupling region and a parallel coupling region and particularly comprises at least one cross coupling region, at least one parallel coupling region and a second cross coupling region or a cross coupling region and at least one parallel coupling region, wherein the at least one cross coupling region comprises two waveguides. By the polarization-irrelevant broadband waveguide beam splitter, a core with large-scale photon calculation can be achieved, and a chip of a multiparticle quantum random walk network is achieved; and since incident light with different polarization codes is supported by polarization-irrelevant characteristic of the structure, higher-dimensional quantum calculation can be achieved.