Multi-state Swap Test Algorithm
@inproceedings{Liu2022MultistateST, title={Multi-state Swap Test Algorithm}, author={Wen Liu and Han-Wen Yin and Zhi-Rao Wang and Wenbing Fan}, year={2022} }
. Estimating the overlap between two states is an important task with several applications in quantum information. However, the typical swap test circuit can only measure a sole pair of quantum states at a time. In this study we designed a recursive quantum circuit to measure overlaps of multiple quantum states | φ 1 ...φ n (cid:105) concurrently with O ( n log n ) controlled-swap (CSWAP) gates and O (log n ) ancillary qubits. This circuit enables us to get all pairwise overlaps among input…