I have a classical vector, which I want to encode it into amplitudes of qubits. The purpose is to implement it in Quantum Neural Networks. For this, I need help for the following:
How can I encode a vector of numbers into qubits? e.g.
vector = [1/2, 1/2, 1/2, 1/2]
If it is a vector of parameters, how to does the encoding work?
To encode a vector of numbers, you can simply to initialize in qiskit.
from qiskit import QuantumCircuit
n = 2
circuit = QuantumCircuit(n)
vector = [1/2, 1/2, 1/2, 1/2]
circuit.initialize(vector)
The number of elements in the vector should equal to 2^n, where n is the number of qubits. If the number of entries is less than 2^n, one can zero the remaining elements in the vector. The vector has to be normalized.
To encode parameters into a quantum circuit, EfficientSU2 provides a very convenient way
from qiskit.circuit.library import EfficientSU2
circuit = EfficientSU2(n, reps=1)