def test_qft(self):
N = 4
q = QubitSystem(N)
# put q into a non-uniform mixed state
hadamard_gate(N) * q
tensor_power(phase_shift_gate(pi), N) * q
# classical FFT of coefficients, normalized to be unitary like the QFT
yhat = fft(q._QubitSystem__coeffs) / sqrt(2 ** N)
qft(q)
self.assertTrue(numpy.max(numpy.abs(q._QubitSystem__coeffs - yhat)) < EPS)
def hadamard_gate(n=1):
"""Factory method for Hadamard gate.
Args:
n: Number of qubits the gate operates on. Default is 1.
"""
return tensor_power(QuantumGate(array([[1./sqrt(2), 1./sqrt(2)],
[1./sqrt(2), -1./sqrt(2)]])), n)