# On-chip deterministic arbitrary-phase-controlling

## TL;DR

This paper introduces a new method for controlling light phases on chips, enabling better performance in photonic circuits and quantum computing.

## Contribution

A three-waveguide coupled configuration enables deterministic arbitrary-phase-controlling on chips.

## Key findings

- The method achieves phase control ranging from 0 to 2π.
- Quantum gate operations were successfully realized using the proposed strategy.
- Silicon-based phase control was verified in the optical communication range.

## Abstract

The stable on-chip deterministic arbitrary-phase-controlling of signal light in micro/nanometer spatial scale is an extremely important basis for large-scale and high-density integrated photonic information processing chips. Conventional phase-controlling methods face with serious limitation of unavoidable crosstalk, length distortion, and fabrication error. To date, it is still a great challenge to achieve deterministic and wide-range on-chip arbitrary-phase-controlling. Here, we report an effective strategy of three-waveguide coupled configuration to realize on-chip deterministic arbitrary-phase-controlling (ranging from 0 to 2π) by combing the dynamic phase and the geometric phase. Based on this strategy, quantum gate operations in an optical permutation-group circuit are successfully realized in femtosecond-laser direct writing sample. To extend the feasibility of this method, on-chip silicon-based deterministic arbitrary-phase-controlling in the optical communication range is also experimentally verified. Our work not only paves the way for fundamental research in chip-scale novel optical devices but also promotes the study of topological quantum computing.