SU(2) = R(θ, θ, ω) = tkje P0 tkje T0 gkjt 0 ejωWkjt 0 ejθL θ! jθgsin 2 ωcos 2 ωej 2 0 = e cos

A.1 Mach-Zehnder Interferometers (MZIs) A basic coherent optical component used in this work is an MZI. One of the most general MZI structures is shown in Figure 15, consisting of two 50-by-50 optical directional couplers and four phase shifters θ, θ, ω, and ω. An MZI can achieve arbitrary 2 2 unitary matrices SU(2). Figure 15: 2-by-2 MZI with top (T), left (L), upper (P), and lower (W) phase shifters. A.2 MZI-based Photonic Tensor Core Architecture By cascading N(N 1)/2MZIs into a triangular mesh (Recks-style) or rectangular mesh (Clementsstyle), we can construct arbitrary N N unitary U(N).