def multi_qubit_decay_bellstate():
"""
Test multiqubit decay
"""
program = Program().inst([RYgate(np.pi / 3)(0), CNOTgate(0, 1)])
noise = NoiseModel(ro_fidelity=1.0)
qvm = QVMConnection(type_trans='density', noise_model=noise)
initial_density = np.zeros((4, 4), dtype=complex)
initial_density[0, 0] = 1.0
cnot_01 = np.kron(I, P0) + np.kron(X, P1)
p1 = 1 - np.exp(-noise.gate_time_1q / noise.T1)
p2 = 1 - np.exp(-noise.gate_time_1q / noise.T2)
kraus_ops_1 = noise_gates['relaxation'](p1)
kraus_ops_2 = noise_gates['dephasing'](p2)
gate_1 = np.kron(np.eye(2), 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 kraus_ops_1:
operator = lifted_gate(ii, kop, 2).todense()
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 kraus_ops_2:
operator = lifted_gate(ii, kop, 2).todense()
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
state = cnot_01.dot(state).dot(cnot_01.T)
p1 = 1 - np.exp(-noise.gate_time_2q / noise.T1)
p2 = 1 - np.exp(-noise.gate_time_2q / noise.T2)
kraus_ops_1 = noise_gates['relaxation'](p1)
kraus_ops_2 = noise_gates['dephasing'](p2)
for ii in range(2):
new_density = np.zeros_like(state)
for kop in kraus_ops_1:
operator = lifted_gate(ii, kop, 2).todense()
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 kraus_ops_2:
operator = lifted_gate(ii, kop, 2).todense()
new_density += operator.dot(state).dot(np.conj(operator).T)
state = new_density
density = qvm.density(program)
assert np.allclose(density.todense(), state)
def test_kraus_through_qvm_t2():
noise = NoiseModel(T1=INFINITY, ro_fidelity=1.0)
qvm = QVMConnection(type_trans='density', noise_model=noise)
rho = random_1q_density()
identity_program = Program().inst(Igate(0))
qvm._density = sps.csc_matrix(rho)
qvm.num_qubits = 1
qvm.load_program(identity_program)
qvm.kernel()
p = 1 - np.exp(-noise.gate_time_1q / noise.T2)
final_density = np.array([[rho[0, 0], (1 - p) * rho[0, 1]],
[(1 - p) * rho[1, 0], rho[1, 1]]])
assert np.allclose(final_density, qvm._density.todense())