def test_thermal_loss_channel(self, setup_eng, tol):
"""Test thermal loss channel with no transmission produces thermal state"""
eng, prog = setup_eng(1)
nbar = 0.43
with prog.context as q:
ops.Dgate(A) | q[0]
ops.ThermalLossChannel(0, nbar) | q[0]
state = eng.run(prog).state
mean_photon, var = state.mean_photon(0)
assert np.allclose(mean_photon, nbar, atol=tol, rtol=0)
assert np.allclose(var, nbar**2 + nbar, atol=tol, rtol=0)
def test_thermalloss_merging_different_nbar(self, tol):
"""test the merging of two Loss channels with same nbar raises exception"""
G = ops.ThermalLossChannel(a, 2 * c)
with pytest.raises(MergeFailure):
merged = G.merge(ops.ThermalLossChannel(b, c))
def test_thermalloss_merging_different_nbar(self, tol):
"""test the merging of Loss and ThermalLoss raises exception"""
G = ops.ThermalLossChannel(a, 2 * c)
with pytest.raises(MergeFailure):
merged = G.merge(ops.LossChannel(b))
def test_thermalloss_merging_same_nbar(self, tol):
"""test the merging of two Loss channels with same nbar"""
G = ops.ThermalLossChannel(a, c)
merged = G.merge(ops.ThermalLossChannel(b, c))
assert np.allclose(merged.p[0], a * b, atol=tol, rtol=0)
