Quantum Fourier Transform
The quantum Fourier transform (QFT) function is the quantum analog for discrete Fourier transform. It is applied on the quantum register state vector.
The state vector x is transformed to y in the following manner:
\[y_{k} = \frac{1}{\sqrt{N}} \sum_{j=0}^{N-1} x_j e^{2\pi i \frac{jk}{N}}\]
Function: qft
Arguments:
target:QArray[QBit]
The target quantum argument is the quantum state on which we apply the QFT.
Example
from classiq import Output, QArray, QBit, allocate, create_model, qft, qfunc
@qfunc
def main(x: Output[QArray[QBit]]):
allocate(4, x)
qft(x)
qmod = create_model(main)
from classiq import synthesize, write_qmod
write_qmod(qmod, "qft")
qprog = synthesize(qmod)