def test_has_symmetric_extension_two_qubit():
"""Check whether 2-qubit state has a symmetric extension."""
rho = np.array([[1, 0, 0, -1], [0, 1, 1 / 2, 0], [0, 1 / 2, 1, 0],
[-1, 0, 0, 1]])
np.testing.assert_equal(has_symmetric_extension(rho), True)
def test_has_symmetric_extension_invalid_dim():
"""Tests for invalid dimension inputs."""
with np.testing.assert_raises(ValueError):
rho = np.identity(6)
has_symmetric_extension(rho, level=1, dim=4)
def test_has_symmetric_extension_level_2_entangled_false_ppt():
"""Entangled state should not have PPT-symmetric extension for some level (level-2)."""
rho = bell(0) * bell(0).conj().T
rho = np.kron(rho, rho)
np.testing.assert_equal(has_symmetric_extension(rho, level=2, dim=2),
False)
def test_has_symmetric_extension_dim_list():
"""Provide dimension of system as list."""
rho = bell(0) * bell(0).conj().T
np.testing.assert_equal(has_symmetric_extension(rho, level=2, dim=[2, 2]),
False)
def test_has_symmetric_extension_entangled_false():
"""Entangled state should not have symmetric extension for some level."""
rho = bell(0) * bell(0).conj().T
np.testing.assert_equal(has_symmetric_extension(rho, level=1), False)
def test_has_symmetric_extension_not_ppt_level_1():
"""Check whether state has level-1 symmetric extension."""
rho = np.identity(4)
np.testing.assert_equal(
has_symmetric_extension(rho, level=1, dim=None, ppt=False), True)