ABSTRACT
Amplitude encoding encodes a real or complexed value vector of the length one into the amplitudes of a quantum state. We describe the top-down strategy and indicate the algorithm step by step. Then we describe the combining states strategy. Instead of representing the binary tree by multi-control rotation gates, we can use controlled SWAP operators with simple rotation gates. The resulting circuits depth is less than top-down divide strategy, however, we require the same number of qubits as the number of rotation gates and the qubits are entangled after the operation.
