On-chip path encoded photonic quantum Toffoli gate
Meng Li, Chu Li, Yang Chen, Lan‐Tian Feng, Linyu Yan, Qian Zhang, Jueming Bao, Bi‐Heng Liu, Xi‐Feng Ren, Jianwei Wang, Shufeng Wang, Yunan Gao, Xiaoyong Hu, Qihuang Gong, Yan Li
Abstract
The quantum Toffoli gate is one of the most important three-qubit gates, but it is challenging to construct a chip according to the complicated traditional circuit. Using the optimized 3D configuration with an overpass waveguide to reduce the circuit complexity, we successfully fabricate an on-chip path encoded photonic quantum Toffoli gate enabled by the 3D capability of the femtosecond laser direct writing (FLDW) for the first time to our knowledge, whose truth-table fidelity is higher than 85.5%. Furthermore, a path encoded four-qubit controlled-controlled-controlled NOT gate is written to confirm the scalability of this resource-saving technique. This work paves the way for the FLDW of more complex and powerful photonic quantum computation chips.