On-chip tunable beam splitter and beam combiner in 1-D open transmission line

Yu-Huan Huang^1*, Kai-Min Hsieh², Fahad Aziz¹, Zhengqi Niu^3,4, Ping-Yi Wen⁵, Yu-Ting Cheng², Jeng-Chung Chen^1,6, Xin Wang², Z. Y. Ou², Zhirong Lin³, Yen-Hsiang Lin^1,6, Io-Chun Hoi^1,2

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
³State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China
⁴ShanghaiTech University, Shanghai, China
⁵Department of Physics, National Chung Cheng University, Chiayi, Taiwan
⁶Center for Quantum Technology, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Yu-Huan Huang, email:ds22772277@gapp.nthu.edu.tw

A beam splitter (BS) is a crucial optical device that separates an incident light beam into two paths. Conventional beam splitters, typically made from coated prisms or glass plates, often suffer from bulkiness, fixed splitting ratios, and right-angled outputs, which may limit their integration into compact optical systems. Superconducting circuits offer a robust platform for exploring the principles of beam splitter and beam combiner and advancing related technologies. Their primary advantage lies in the ability to engineer and tailor light-matter interactions. In this work, we present a nonlinear beam splitter and beam combiner utilizing a superconducting artificial atom in one-dimensional waveguide. This beam splitter is highly versatile, with adjustable transparency ranging from unity to zero. Additionally, the beam combiner can merge two coherent beams, producing interference fringes as the relative phase between the beams changes. These findings highlight the potential of superconducting circuits in developing microwave-based Mach-Zehnder Interferometers (MZIs) and quantum computing with linear optics.

Keywords: Superconducting qubit, Beam splitter, Waveguide QED