Stable Signal Processing with a Photonic Processor

A key objective in the development of integrated photonic circuits for large-scale optical quantum information processing is achieving both reconfigurability and stable output signals. One outcome of this development is the creation of multimode photonic processors, or reconfigurable multimode interferometers, which have broad applications in both quantum and classical information processing. However, active cooling systems introduce phase fluctuations in multi-port input signals, leading to instability in interference patterns and degrading signal processing precision. In this work, we implement an on-chip feedback control to mitigate input signal phase fluctuation. This approach reduces phase instability by more than 10-fold for multi-port input signals. This significantly enhances the precision and reliability of signal processing within the photonic processor. To validate the stability and repeatability of matrix multiplication using a feedback control scheme on a photonic processor, we successfully implemented Hadamard transformations of different orders with multi-port input signals.