Towards the Information-Theoretic Limit of Programmable Photonics
<|reference_start|>Towards the Information-Theoretic Limit of Programmable Photonics: The scalability of many programmable photonic circuits is limited by the $2\pi$ tuning range needed for the constituent phase shifters. To address this problem, we introduce the concept of a phase-efficient circuit architecture, where the average phase shift is $\ll 2\pi$. We derive a universal information-theoretic limit to the phase-shift efficiency of universal multiport interferometers, and propose a "3-MZI" architecture that approaches this limit to within a factor of $2\times$, approximately a $10\times$ reduction in average phase shift over the prior art, where the average phase shift scales inversely with system size as $O(1/\sqrt{N})$. For non-unitary circuits, we show that the 3-MZI saturates the theoretical bound for Gaussian-distributed target matrices. Using this architecture, we show optical neural network training with all phase shifters constrained to $\lesssim 0.2$ radians without loss of accuracy.<|reference_end|>
@article{hamerly2024towards,
    title={Towards the Information-Theoretic Limit of Programmable Photonics},
    author={Ryan Hamerly, Jasvith Raj Basani, Alexander Sludds, Sri Krishna
  Vadlamani, and Dirk Englund},
    journal={arXiv preprint arXiv:2408.09673},
    year={2024},
    archivePrefix={arXiv},
    eprint={2408.09673},
    primaryClass={physics.optics cs.ET}
}