def setUp(self):
self.n_qubits = 5
self.constant = 1.7
self.chemical_potential = 2.
# Obtain random Hermitian and antisymmetric matrices
self.hermitian_mat = random_hermitian_matrix(self.n_qubits)
self.antisymmetric_mat = random_antisymmetric_matrix(self.n_qubits)
self.combined_hermitian = (
self.hermitian_mat -
self.chemical_potential * numpy.eye(self.n_qubits))
# Initialize a particle-number-conserving Hamiltonian
self.quad_ham_pc = QuadraticHamiltonian(self.hermitian_mat,
constant=self.constant)
# Initialize a non-particle-number-conserving Hamiltonian
self.quad_ham_npc = QuadraticHamiltonian(self.hermitian_mat,
self.antisymmetric_mat,
self.constant,
self.chemical_potential)
# Initialize the sparse operators and get their ground energies
self.quad_ham_pc_sparse = get_sparse_operator(self.quad_ham_pc)
self.quad_ham_npc_sparse = get_sparse_operator(self.quad_ham_npc)
self.pc_ground_energy, self.pc_ground_state = get_ground_state(
self.quad_ham_pc_sparse)
self.npc_ground_energy, self.npc_ground_state = get_ground_state(
self.quad_ham_npc_sparse)
def test_ground_state_particle_nonconserving(self):
"""Test getting the ground state preparation circuit for a Hamiltonian
that does not conserve particle number."""
for n_qubits in self.n_qubits_range:
# Initialize a particle-number-conserving Hamiltonian
quadratic_hamiltonian = random_quadratic_hamiltonian(
n_qubits, False, True)
# Compute the true ground state
sparse_operator = get_sparse_operator(quadratic_hamiltonian)
ground_energy, _ = get_ground_state(sparse_operator)
# Obtain the circuit
circuit_description, start_orbitals = (
gaussian_state_preparation_circuit(quadratic_hamiltonian))
# Initialize the starting state
state = jw_configuration_state(start_orbitals, n_qubits)
# Apply the circuit
particle_hole_transformation = (
jw_sparse_particle_hole_transformation_last_mode(n_qubits))
for parallel_ops in circuit_description:
for op in parallel_ops:
if op == 'pht':
state = particle_hole_transformation.dot(state)
else:
i, j, theta, phi = op
state = jw_sparse_givens_rotation(
i, j, theta, phi, n_qubits).dot(state)
# Check that the state obtained using the circuit is a ground state
difference = sparse_operator * state - ground_energy * state
discrepancy = numpy.amax(numpy.abs(difference))
self.assertAlmostEqual(discrepancy, 0)
def test_sparse_numerically(self):
# Check FCI energy.
energy, wavefunction = get_ground_state(self.hamiltonian_matrix)
self.assertAlmostEqual(energy, self.molecule.fci_energy)
expected_energy = expectation(self.hamiltonian_matrix, wavefunction)
self.assertAlmostEqual(expected_energy, energy)
# Make sure you can reproduce Hartree energy.
hf_state = jw_hartree_fock_state(self.molecule.n_electrons,
count_qubits(self.qubit_hamiltonian))
hf_density = get_density_matrix([hf_state], [1.])
# Make sure you can reproduce Hartree-Fock energy.
hf_state = jw_hartree_fock_state(self.molecule.n_electrons,
count_qubits(self.qubit_hamiltonian))
hf_density = get_density_matrix([hf_state], [1.])
expected_hf_density_energy = expectation(self.hamiltonian_matrix,
hf_density)
expected_hf_energy = expectation(self.hamiltonian_matrix, hf_state)
self.assertAlmostEqual(expected_hf_energy, self.molecule.hf_energy)
self.assertAlmostEqual(expected_hf_density_energy,
self.molecule.hf_energy)
def test_ground_state_particle_nonconserving(self):
"""Test getting the ground state of a Hamiltonian that does not
conserve particle number."""
for n_qubits in self.n_qubits_range:
# Initialize a non-particle-number-conserving Hamiltonian
quadratic_hamiltonian = random_quadratic_hamiltonian(
n_qubits, False)
# Compute the true ground state
sparse_operator = get_sparse_operator(quadratic_hamiltonian)
ground_energy, _ = get_ground_state(sparse_operator)
# Compute the ground state using the circuit
circuit_energy, circuit_state = (
jw_get_gaussian_state(quadratic_hamiltonian))
# Check that the energies match
self.assertAlmostEqual(ground_energy, circuit_energy)
# Check that the state obtained using the circuit is a ground state
difference = (sparse_operator * circuit_state -
ground_energy * circuit_state)
discrepancy = numpy.amax(numpy.abs(difference))
self.assertAlmostEqual(discrepancy, 0)