An Optimal Design for Universal Multiport Interferometers

摘要

Universal multiport interferometers, which can be programmed to implement anylinear transformation between multiple channels, are emerging as a powerfultool for both classical and quantum photonics. These interferometers aretypically composed of a regular mesh of beam splitters and phase shifters,allowing for straightforward fabrication using integrated photonicarchitectures and ready scalability. The current, standard design for universalmultiport interferometers is based on work by Reck et al (Phys. Rev. Lett. 73,58, 1994). We demonstrate a new design for universal multiport interferometersbased on an alternative arrangement of beam splitters and phase shifters, whichoutperforms that by Reck et al. Our design occupies half the physical footprintof the Reck design and is significantly more robust to optical losses.