def test_gate_error_handling():
with pytest.raises(ValueError,
match='`target_state` must be a 1d numpy array.'):
cirq.StatePreparationChannel(np.eye(2))
with pytest.raises(ValueError,
match='Matrix width \\(5\\) is not a power of 2'):
cirq.StatePreparationChannel(np.ones(shape=5))
def test_equality_of_gates():
state = np.array([1, 0, 0, 0], dtype=np.complex64)
gate_1 = cirq.StatePreparationChannel(state)
gate_2 = cirq.StatePreparationChannel(state)
assert gate_1 == gate_2, "Equal state not leading to same gate"
assert not gate_1 == state, "Incompatible objects shouldn't be equal"
state = np.array([0, 1, 0, 0], dtype=np.complex64)
gate_3 = cirq.StatePreparationChannel(state, name='gate_a')
gate_4 = cirq.StatePreparationChannel(state, name='gate_b')
assert gate_3 == gate_4, "Equal state with different names not leading to same gate"
assert gate_1 != gate_3, "Different states shouldn't lead to same gate"
def test_state_prep_channel_kraus_small():
gate = cirq.StatePreparationChannel(np.array([0.0,
1.0]))(cirq.LineQubit(0))
np.testing.assert_almost_equal(cirq.kraus(gate), (np.array(
[[0.0, 0.0], [1.0, 0.0]]), np.array([[0.0, 0.0], [0.0, 1.0]])))
assert cirq.has_kraus(gate)
assert not cirq.has_mixture(gate)
gate = cirq.StatePreparationChannel(np.array([1.0,
0.0]))(cirq.LineQubit(0))
np.testing.assert_almost_equal(cirq.kraus(gate), (np.array(
[[1.0, 0.0], [0.0, 0.0]]), np.array([[0.0, 1.0], [0.0, 0.0]])))
assert cirq.has_kraus(gate)
assert not cirq.has_mixture(gate)
def test_gate_params():
state = np.array([1, 0, 0, 0], dtype=np.complex64)
gate = cirq.StatePreparationChannel(state)
assert gate.num_qubits() == 2
assert not gate._has_unitary_()
assert gate._has_kraus_()
assert str(
gate) == 'StatePreparationChannel([1.+0.j 0.+0.j 0.+0.j 0.+0.j])'
cirq.testing.assert_equivalent_repr(gate)
def test_gate_params():
state = np.array([1, 0, 0, 0], dtype=np.complex64)
gate = cirq.StatePreparationChannel(state)
assert gate.num_qubits() == 2
assert not gate._has_unitary_()
assert gate._has_kraus_()
assert (
repr(gate) ==
'cirq.StatePreparationChannel(np.array([(1+0j), 0j, 0j, 0j], dtype=np.complex128))'
)
def test_approx_equality_of_gates():
state = np.array([1, 0, 0, 0], dtype=np.complex64)
gate_1 = cirq.StatePreparationChannel(state)
gate_2 = cirq.StatePreparationChannel(state)
assert cirq.approx_eq(gate_1,
gate_2), "Equal state not leading to same gate"
assert not cirq.approx_eq(
gate_1, state), "Different object types cannot be approx equal"
perturbed_state = np.array([1 - 1e-9, 1e-10, 0, 0], dtype=np.complex64)
gate_3 = cirq.StatePreparationChannel(perturbed_state)
assert cirq.approx_eq(
gate_3, gate_1), "Almost equal states should lead to the same gate"
different_state = np.array([1 - 1e-5, 1e-4, 0, 0], dtype=np.complex64)
gate_4 = cirq.StatePreparationChannel(different_state)
assert not cirq.approx_eq(
gate_4, gate_1), "Different states should not lead to the same gate"
assert cirq.approx_eq(
gate_4, gate_1, atol=1e-3
), "Gates with difference in states under the tolerance aren't equal"
assert not cirq.approx_eq(
gate_4, gate_1, atol=1e-6
), "Gates with difference in states over the tolerance are equal"
def test_state_prep_gate_printing():
circuit = cirq.Circuit()
qubits = cirq.LineQubit.range(2)
gate = cirq.StatePreparationChannel(np.array([1, 0, 0, 1]) / np.sqrt(2))
circuit.append(cirq.H(qubits[0]))
circuit.append(cirq.CNOT(qubits[0], qubits[1]))
circuit.append(gate(qubits[0], qubits[1]))
cirq.testing.assert_has_diagram(
circuit,
"""
0: ───H───@───StatePreparation[1]───
│ │
1: ───────X───StatePreparation[2]───
""",
)
def test_state_prep_channel_kraus(state):
qubits = cirq.LineQubit.range(2)
gate = cirq.StatePreparationChannel(state)(qubits[0], qubits[1])
state = state / np.linalg.norm(state)
np.testing.assert_almost_equal(
cirq.kraus(gate),
(
np.array([state, np.zeros(4),
np.zeros(4),
np.zeros(4)]).T,
np.array([np.zeros(4), state,
np.zeros(4),
np.zeros(4)]).T,
np.array([np.zeros(4),
np.zeros(4), state,
np.zeros(4)]).T,
np.array([np.zeros(4),
np.zeros(4),
np.zeros(4), state]).T,
),
)
def test_equality_of_gates():
state = np.array([1, 0, 0, 0], dtype=np.complex64)
gate_1 = cirq.StatePreparationChannel(state)
gate_2 = cirq.StatePreparationChannel(state)
assert gate_1 == gate_2, "Equal state not leading to same gate"
assert not gate_1 == state, "Incompatible objects shouldn't be equal"