def test_measure_density_matrix_not_square():
with pytest.raises(ValueError, match='not square'):
cirq.measure_density_matrix(np.array([1, 0, 0]), [1])
with pytest.raises(ValueError, match='not square'):
cirq.measure_density_matrix(np.array([1, 0, 0, 0]).reshape((2, 1, 2)),
[1],
qid_shape=(2, 1))
def test_measure_density_matrix_seed():
n = 5
matrix = np.eye(2**n) / 2**n
bits, out_matrix1 = cirq.measure_density_matrix(matrix, range(n), seed=1234)
assert bits == [False, False, True, True, False]
bits, out_matrix2 = cirq.measure_density_matrix(
matrix, range(n), seed=np.random.RandomState(1234))
assert bits == [False, False, True, True, False]
np.testing.assert_allclose(out_matrix1, out_matrix2)
def test_measure_density_matrix_partial_indices_all_orders():
for perm in itertools.permutations([0, 1, 2]):
for x in range(8):
matrix = cirq.to_valid_density_matrix(x, 3)
bits, out_matrix = cirq.measure_density_matrix(matrix, perm)
np.testing.assert_almost_equal(matrix, out_matrix)
assert bits == [bool(1 & (x >> (2 - p))) for p in perm]
def test_measure_density_matrix_partial_indices():
for index in range(3):
for x in range(8):
matrix = cirq.to_valid_density_matrix(x, 3)
bits, out_matrix = cirq.measure_density_matrix(matrix, [index])
np.testing.assert_almost_equal(out_matrix, matrix)
assert bits == [bool(1 & (x >> (2 - index)))]
def test_measure_state_no_indices_out_is_not_matrix():
matrix = cirq.to_valid_density_matrix(0, 3)
out = np.zeros_like(matrix)
bits, out_matrix = cirq.measure_density_matrix(matrix, [], out=out)
assert [] == bits
np.testing.assert_almost_equal(out_matrix, matrix)
assert out is out_matrix
assert out is not matrix
def test_measure_density_matrix_out_is_matrix():
matrix = matrix_000_plus_010()
bits, out_matrix = cirq.measure_density_matrix(matrix, [2, 1, 0], out=matrix)
expected_state = np.zeros(8, dtype=np.complex64)
expected_state[2 if bits[1] else 0] = 1.0
expected_matrix = np.outer(np.conj(expected_state), expected_state)
np.testing.assert_array_almost_equal(out_matrix, expected_matrix)
assert out_matrix is matrix
def test_measure_density_matrix_computational_basis_reshaped():
results = []
for x in range(8):
matrix = np.reshape(cirq.to_valid_density_matrix(x, 3), (2,) * 6)
bits, out_matrix = cirq.measure_density_matrix(matrix, [2, 1, 0])
results.append(bits)
np.testing.assert_almost_equal(out_matrix, matrix)
expected = [list(reversed(x)) for x in list(itertools.product([False, True], repeat=3))]
assert results == expected
def test_measure_density_matrix_collapse():
matrix = matrix_000_plus_010()
for _ in range(10):
bits, out_matrix = cirq.measure_density_matrix(matrix, [2, 1, 0])
assert bits in [[False, False, False], [False, True, False]]
expected = np.zeros(8, dtype=np.complex64)
if bits[1]:
expected[2] = 1j
else:
expected[0] = 1
expected_matrix = np.outer(np.conj(expected), expected)
np.testing.assert_almost_equal(out_matrix, expected_matrix)
assert out_matrix is not matrix
# Partial sample is correct.
for _ in range(10):
bits, out_matrix = cirq.measure_density_matrix(matrix, [2])
np.testing.assert_almost_equal(out_matrix, matrix)
assert bits == [False]
bits, out_matrix = cirq.measure_density_matrix(matrix, [0])
np.testing.assert_almost_equal(out_matrix, matrix)
assert bits == [False]
def test_measure_state_empty_density_matrix():
matrix = np.zeros(shape=())
bits, out_matrix = cirq.measure_density_matrix(matrix, [])
assert [] == bits
np.testing.assert_almost_equal(matrix, out_matrix)
def test_measure_state_no_indices_out_is_matrix():
matrix = cirq.to_valid_density_matrix(0, 3)
bits, out_matrix = cirq.measure_density_matrix(matrix, [], out=matrix)
assert [] == bits
np.testing.assert_almost_equal(out_matrix, matrix)
assert out_matrix is matrix
def test_measure_density_matrix_out_of_range():
matrix = cirq.to_valid_density_matrix(0, 3)
with pytest.raises(IndexError, match='-2'):
cirq.measure_density_matrix(matrix, [-2])
with pytest.raises(IndexError, match='3'):
cirq.measure_density_matrix(matrix, [3])
def test_measure_density_matrix_tensor_different_left_right_shape():
with pytest.raises(ValueError, match='not equal'):
cirq.measure_density_matrix(np.array([1, 0, 0, 0]).reshape(
(2, 2, 1, 1)), [1],
qid_shape=(2, 1))
def test_measure_density_matrix_higher_powers_of_two():
with pytest.raises(ValueError, match='powers of two'):
cirq.measure_density_matrix(np.ones((2, 4, 2, 4)) / 8, [1])
def test_measure_density_matrix_not_power_of_two():
with pytest.raises(ValueError, match='power of two'):
cirq.measure_density_matrix(np.ones((3, 3)) / 3, [1])
with pytest.raises(ValueError, match='power of two'):
cirq.measure_density_matrix(np.ones((2, 3, 2, 3)) / 6, [1])
def test_measure_state_out_is_not_matrix():
matrix = matrix_000_plus_010()
out = np.zeros_like(matrix)
_, out_matrix = cirq.measure_density_matrix(matrix, [2, 1, 0], out=out)
assert out is not matrix
assert out is out_matrix
def test_measure_density_matrix_not_square():
with pytest.raises(ValueError, match='not square'):
cirq.measure_density_matrix(np.array([1, 0, 0]), [1])
