def test_multiqubit_decay_bellstate():
program = Program(RY(np.pi / 3, 0), CNOT(0, 1))
# commence manually dotting the above program
initial_density = np.zeros((4, 4), dtype=complex)
initial_density[0, 0] = 1.0
gate_time_1q = 50e-9
T1 = 30e-6
T2 = 15e-6
p1 = 1 - np.exp(-gate_time_1q / T1)
p2 = 1 - np.exp(-gate_time_1q / T2)
# RY
gate_1 = np.kron(np.eye(2), qmats.RY(np.pi / 3))
state = gate_1.dot(initial_density).dot(np.conj(gate_1).T)
for ii in range(2):
new_density = np.zeros_like(state)
for kop in qmats.relaxation_operators(p1):
operator = lifted_gate_matrix(matrix=kop,
qubit_inds=[ii],
n_qubits=2)
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
for ii in range(2):
new_density = np.zeros_like(state)
for kop in qmats.dephasing_operators(p2):
operator = lifted_gate_matrix(matrix=kop,
qubit_inds=[ii],
n_qubits=2)
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
# CNOT
# TODO: different 1q, 2q noise probabilities
cnot_01 = np.kron(qmats.I, qmats.P0) + np.kron(qmats.X, qmats.P1)
state = cnot_01.dot(state).dot(cnot_01.T)
gate_time_2q = 150e-9
p1 = 1 - np.exp(-gate_time_2q / T1)
p2 = 1 - np.exp(-gate_time_2q / T2)
for ii in range(2):
new_density = np.zeros_like(state)
for kop in qmats.relaxation_operators(p1):
operator = lifted_gate_matrix(matrix=kop,
qubit_inds=[ii],
n_qubits=2)
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
for ii in range(2):
new_density = np.zeros_like(state)
for kop in qmats.dephasing_operators(p2):
operator = lifted_gate_matrix(matrix=kop,
qubit_inds=[ii],
n_qubits=2)
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
qam = PyQVM(n_qubits=2,
quantum_simulator_type=ReferenceDensitySimulator,
post_gate_noise_probabilities={
'relaxation': p1,
'dephasing': p2
})
qam.execute(program)
assert np.allclose(qam.wf_simulator.density, state)
def test_kraus_t2_normalization():
kraus_ops = dephasing_operators(0.75)
total = np.zeros((2, 2), dtype=complex)
for kop in kraus_ops:
total += np.conj(kop.T).dot(kop)
assert np.allclose(total, np.eye(2))