def test_default_tolerance():
a, b = cirq.LineQubit.range(2)
final_state_vector = (cirq.Simulator().simulate(
cirq.Circuit(cirq.H(a), cirq.H(b), cirq.CZ(a, b),
cirq.measure(a))).final_state_vector.reshape((2, 2)))
# Here, we do NOT specify the default tolerance. It is merely to check that the default value
# is reasonable.
cirq.sub_state_vector(final_state_vector, [0])
def test_sub_state_vector_non_kron():
a = np.array([1, 0, 0, 0, 0, 0, 0, 1]) / np.sqrt(2)
b = np.array([1, 1]) / np.sqrt(2)
state = np.kron(a, b).reshape((2, 2, 2, 2))
for q1 in [0, 1, 2]:
assert cirq.sub_state_vector(state, [q1], default=None, atol=1e-8) is None
for q1 in [0, 1, 2]:
assert cirq.sub_state_vector(state, [q1, 3], default=None, atol=1e-8) is None
with pytest.raises(ValueError, match='factored'):
_ = cirq.sub_state_vector(a, [0], atol=1e-8)
assert cirq.equal_up_to_global_phase(cirq.sub_state_vector(state, [3]), b, atol=1e-8)
def test_sub_state_vector_bad_subset():
a = cirq.testing.random_superposition(4)
b = cirq.testing.random_superposition(8)
state = np.kron(a, b).reshape((2, 2, 2, 2, 2))
for q1 in range(5):
assert cirq.sub_state_vector(state, [q1], default=None, atol=1e-8) is None
for q1 in range(2):
for q2 in range(2, 5):
assert cirq.sub_state_vector(state, [q1, q2], default=None, atol=1e-8) is None
for q3 in range(2, 5):
assert cirq.sub_state_vector(state, [0, 1, q3], default=None, atol=1e-8) is None
for q4 in range(2):
assert cirq.sub_state_vector(state, [2, 3, 4, q4], default=None, atol=1e-8) is None
def test_deprecated():
a = np.arange(4) / np.linalg.norm(np.arange(4))
with cirq.testing.assert_logs('subwavefunction', 'sub_state_vector',
'deprecated'):
_ = cirq.subwavefunction(a, [0, 1], atol=1e-8)
with cirq.testing.assert_logs('wavefunction', 'state_vector',
'deprecated'):
# pylint: disable=unexpected-keyword-arg,no-value-for-parameter
_ = cirq.sub_state_vector(wavefunction=a,
keep_indices=[0, 1],
atol=1e-8)
with cirq.testing.assert_logs(
'wavefunction_partial_trace_as_mixture',
'partial_trace_of_state_vector_as_mixture',
'deprecated',
):
_ = cirq.wavefunction_partial_trace_as_mixture(a, [0])
with cirq.testing.assert_logs('wavefunction', 'state_vector',
'deprecated'):
# pylint: disable=unexpected-keyword-arg,no-value-for-parameter
_ = cirq.partial_trace_of_state_vector_as_mixture(wavefunction=a,
keep_indices=[0])
def test_sub_state_vector_invalid_inputs():
# State cannot be expressed as a separable pure state.
with pytest.raises(ValueError, match='7'):
cirq.sub_state_vector(np.arange(7), [1, 2], atol=1e-8)
# State shape does not conform to input requirements.
with pytest.raises(ValueError, match='shaped'):
cirq.sub_state_vector(np.arange(16).reshape((2, 4, 2)), [1, 2], atol=1e-8)
with pytest.raises(ValueError, match='shaped'):
cirq.sub_state_vector(np.arange(16).reshape((16, 1)), [1, 2], atol=1e-8)
with pytest.raises(ValueError, match='normalized'):
cirq.sub_state_vector(np.arange(16), [1, 2], atol=1e-8)
# Bad choice of input indices.
state = np.arange(8) / np.linalg.norm(np.arange(8))
with pytest.raises(ValueError, match='2, 2'):
cirq.sub_state_vector(state, [1, 2, 2], atol=1e-8)
state = np.array([1, 0, 0, 0]).reshape((2, 2))
with pytest.raises(ValueError, match='invalid'):
cirq.sub_state_vector(state, [5], atol=1e-8)
with pytest.raises(ValueError, match='invalid'):
cirq.sub_state_vector(state, [0, 1, 2], atol=1e-8)
def test_sub_state_vector():
a = np.arange(4) / np.linalg.norm(np.arange(4))
b = (np.arange(8) + 3) / np.linalg.norm(np.arange(8) + 3)
c = (np.arange(16) + 1) / np.linalg.norm(np.arange(16) + 1)
state = np.kron(np.kron(a, b), c).reshape(2, 2, 2, 2, 2, 2, 2, 2, 2)
assert cirq.equal_up_to_global_phase(cirq.sub_state_vector(a, [0, 1], atol=1e-8), a)
assert cirq.equal_up_to_global_phase(cirq.sub_state_vector(b, [0, 1, 2], atol=1e-8), b)
assert cirq.equal_up_to_global_phase(cirq.sub_state_vector(c, [0, 1, 2, 3], atol=1e-8), c)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(state, [0, 1], atol=1e-15), a.reshape(2, 2)
)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(state, [2, 3, 4], atol=1e-15), b.reshape(2, 2, 2)
)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(state, [5, 6, 7, 8], atol=1e-15), c.reshape(2, 2, 2, 2)
)
# Output state vector conforms to the shape of the input state vector.
reshaped_state = state.reshape(-1)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(reshaped_state, [0, 1], atol=1e-15), a
)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(reshaped_state, [2, 3, 4], atol=1e-15), b
)
assert cirq.equal_up_to_global_phase(
cirq.sub_state_vector(reshaped_state, [5, 6, 7, 8], atol=1e-15), c
)
# Reject factoring for very tight tolerance.
assert cirq.sub_state_vector(state, [0, 1], default=None, atol=1e-16) is None
assert cirq.sub_state_vector(state, [2, 3, 4], default=None, atol=1e-16) is None
assert cirq.sub_state_vector(state, [5, 6, 7, 8], default=None, atol=1e-16) is None
# Permit invalid factoring for loose tolerance.
for q1 in range(9):
assert cirq.sub_state_vector(state, [q1], default=None, atol=1) is not None
