def test_canonical(self):
"""Test that the returned canonical matrix has the right form."""
n = 7
# Obtain a random antisymmetric matrix
rand_mat = numpy.random.randn(2 * n, 2 * n)
antisymmetric_matrix = rand_mat - rand_mat.T
canonical, orthogonal = antisymmetric_canonical_form(
antisymmetric_matrix)
for i in range(2 * n):
for j in range(2 * n):
if i < n and j == n + i:
self.assertTrue(canonical[i, j] > -EQ_TOLERANCE)
elif i >= n and j == i - n:
self.assertTrue(canonical[i, j] < EQ_TOLERANCE)
else:
self.assertAlmostEqual(canonical[i, j], 0.)
diagonal = canonical[range(n), range(n, 2 * n)]
for i in range(n - 1):
self.assertTrue(diagonal[i] <= diagonal[i + 1])
def test_diagonalizes_quadratic_hamiltonian(self):
"""Test that the unitary returned indeed diagonalizes a
quadratic Hamiltonian."""
hermitian_part = self.quad_ham_npc.combined_hermitian_part
antisymmetric_part = self.quad_ham_npc.antisymmetric_part
block_matrix = numpy.zeros((2 * self.n_qubits, 2 * self.n_qubits),
dtype=complex)
block_matrix[:self.n_qubits, :self.n_qubits] = antisymmetric_part
block_matrix[:self.n_qubits, self.n_qubits:] = hermitian_part
block_matrix[self.n_qubits:, :self.n_qubits] = -hermitian_part.conj()
block_matrix[self.n_qubits:, self.n_qubits:] = (
-antisymmetric_part.conj())
majorana_matrix, majorana_constant = self.quad_ham_npc.majorana_form()
canonical, orthogonal = antisymmetric_canonical_form(majorana_matrix)
ferm_unitary = diagonalizing_fermionic_unitary(majorana_matrix)
diagonalized = ferm_unitary.conj().dot(
block_matrix.dot(ferm_unitary.T.conj()))
for i in numpy.ndindex((2 * self.n_qubits, 2 * self.n_qubits)):
self.assertAlmostEqual(diagonalized[i], canonical[i])
def test_diagonalizing_bogoliubov_transform(self):
"""Test getting the diagonalizing Bogoliubov transformation."""
hermitian_part = self.quad_ham_npc.combined_hermitian_part
antisymmetric_part = self.quad_ham_npc.antisymmetric_part
block_matrix = numpy.zeros((2 * self.n_qubits, 2 * self.n_qubits),
dtype=complex)
block_matrix[:self.n_qubits, :self.n_qubits] = antisymmetric_part
block_matrix[:self.n_qubits, self.n_qubits:] = hermitian_part
block_matrix[self.n_qubits:, :self.n_qubits] = -hermitian_part.conj()
block_matrix[self.n_qubits:, self.n_qubits:] = (
-antisymmetric_part.conj())
ferm_unitary = self.quad_ham_npc.diagonalizing_bogoliubov_transform()
# Check that the transformation is diagonalizing
majorana_matrix, majorana_constant = self.quad_ham_npc.majorana_form()
canonical, orthogonal = antisymmetric_canonical_form(majorana_matrix)
diagonalized = ferm_unitary.conj().dot(
block_matrix.dot(ferm_unitary.T.conj()))
for i in numpy.ndindex((2 * self.n_qubits, 2 * self.n_qubits)):
self.assertAlmostEqual(diagonalized[i], canonical[i])
lower_unitary = ferm_unitary[self.n_qubits:]
lower_left = lower_unitary[:, :self.n_qubits]
lower_right = lower_unitary[:, self.n_qubits:]
# Check that lower_left and lower_right satisfy the constraints
# necessary for the transformed fermionic operators to satisfy
# the fermionic anticommutation relations
constraint_matrix_1 = (lower_left.dot(lower_left.T.conj()) +
lower_right.dot(lower_right.T.conj()))
constraint_matrix_2 = (lower_left.dot(lower_right.T) +
lower_right.dot(lower_left.T))
identity = numpy.eye(self.n_qubits, dtype=complex)
for i in numpy.ndindex((self.n_qubits, self.n_qubits)):
self.assertAlmostEqual(identity[i], constraint_matrix_1[i])
self.assertAlmostEqual(0., constraint_matrix_2[i])
def test_not_antisymmetric(self):
n = 4
ones_mat = numpy.ones((n, n))
with self.assertRaises(ValueError):
_ = antisymmetric_canonical_form(ones_mat)
def test_bad_dimensions(self):
n, p = (3, 4)
ones_mat = numpy.ones((n, p))
with self.assertRaises(ValueError):
_ = antisymmetric_canonical_form(ones_mat)
