def test_br_term_mult(secular):
"BR Tools : br_term_mult"
dimension = 10
time = 1.0
atol = 1e-12
for _ in range(10):
H = qutip.rand_herm(dimension, 0.5)
basis = H.eigenstates()[1]
L_diagonal = qutip.liouvillian(H.transform(basis))
evals = np.empty((dimension,), dtype=np.float64)
evecs = _test_zheevr(H.full('F'), evals)
operator = qutip.rand_herm(dimension, 0.5)
a_ops = [[operator, lambda w: 1.0]]
vec = np.ones((dimension*dimension,), dtype=np.complex128)
br_tensor, _ = qutip.bloch_redfield_tensor(H, a_ops,
use_secular=secular)
target = (br_tensor - L_diagonal).data.dot(vec)
calculated = np.zeros_like(target)
_test_br_term_mult(time, operator.full('F'), evecs, evals, vec,
calculated, secular, 0.1, atol)
assert np.allclose(target, calculated)
def test_pull_572_error():
"""
brmesolve: Check for #572 bug.
"""
w1, w2, w3 = 1, 2, 3
gamma2, gamma3 = 0.1, 0.1
id2 = qutip.qeye(2)
# Hamiltonian for three uncoupled qubits
H = (w1 / 2. * qutip.tensor(qutip.sigmaz(), id2, id2) +
w2 / 2. * qutip.tensor(id2, qutip.sigmaz(), id2) +
w3 / 2. * qutip.tensor(id2, id2, qutip.sigmaz()))
# White noise
def S2(w):
return gamma2
def S3(w):
return gamma3
qubit_2_x = qutip.tensor(id2, qutip.sigmax(), id2)
qubit_3_x = qutip.tensor(id2, id2, qutip.sigmax())
# Bloch-Redfield tensor including dissipation for qubits 2 and 3 only
R, ekets = qutip.bloch_redfield_tensor(H,
[[qubit_2_x, S2], [qubit_3_x, S3]])
# Initial state : first qubit is excited
grnd2 = qutip.sigmam() * qutip.sigmap() # 2x2 ground
exc2 = qutip.sigmap() * qutip.sigmam() # 2x2 excited state
ini = qutip.tensor(exc2, grnd2, grnd2) # Full system
# Projector on the excited state of qubit 1
proj_up1 = qutip.tensor(exc2, id2, id2)
# Solution of the master equation
times = np.linspace(0, 10. / gamma3, 1000)
sol = qutip.bloch_redfield_solve(R, ekets, ini, times, [proj_up1])
np.testing.assert_allclose(sol[0], np.ones_like(times))
delta = 0.2 * 2 * np.pi
eps0 = 1.0 * 2 * np.pi
gamma1 = 0.5
H = -delta / 2.0 * qt.sigmax() - eps0 / 2.0 * qt.sigmaz()
def ohmic_spectrum(w):
if w == 0.0: # dephasing inducing noise
return gamma1
else: # relaxation inducing noise
return gamma1 / 2 * (w / (2 * np.pi)) * (w > 0.0)
R, ekets = qt.bloch_redfield_tensor(H, [qt.sigmax()], [ohmic_spectrum])
"""
Last part
"""
tlist = np.linspace(0, 15.0, 1000)
psi0 = qt.rand_ket(2)
e_ops = [qt.sigmax(), qt.sigmay(), qt.sigmaz()]
expt_list = qt.bloch_redfield_solve(R, ekets, psi0, tlist, e_ops)
sphere = qt.Bloch()
sphere.add_points([expt_list[0], expt_list[1], expt_list[2]])
sphere.vector_color = ['r']
sphere.add_vectors(np.array([delta, 0, eps0]) / np.sqrt(delta**2 + eps0**2))
sphere.make_sphere()
