  Reconfigurable quantum photonic processors are an essential technology for
photonic quantum computing. Although most large-scale reconfigurable quantum
photonic processors were demonstrated at the telecommunications C band around
1550 nm, high-performance single photon light sources utilizing quantum dots
that are well-suited for photonic quantum computing operate at a variety of
wavelengths. Thus, a demand exists for the compatibility of quantum photonic
processors with a larger wavelength range. Silicon nitride (SiN) has a high
confinement and wide transparency window, enabling compact, low-loss quantum
photonic processors at wavelengths outside the C band. Here, we report a SiN
universal 12-mode quantum photonic processor with optimal operation at a
wavelength of 940 nm, which is compatible with InGaAs quantum dot light sources
that emit light in the 900 nm to 970 nm wavelength range. The processor can
implement arbitrary unitary transformations on its 12 input modes with a
fidelity of 98.6 %, with a mean optical loss of 3.4 dB/mode.
