“…In order to obtain the overlap | φ i | φ j | 2 between arbitrary two states |φ i , |φ j (i, j = 1, 2, ..., m; i = j), there is a trivial solution which requires n(n−1) 2 Swap Tests and n(n−1) 2 ancillary qubits. In [21], X. Gitiaux In this paper, following the idea of [21], we design a new circuit U 4 with two ancillaries, two controlled-swap(CSWAP) gates , and two simple Swap Test.…”