def test_tapered_op(self):
# set_qiskit_chemistry_logging(logging.DEBUG)
tapered_ops = []
for coeff in itertools.product([1, -1], repeat=len(self.sq_list)):
tapered_op = Operator.qubit_tapering(self.qubit_op, self.cliffords,
self.sq_list, list(coeff))
tapered_ops.append((list(coeff), tapered_op))
smallest_idx = 0 # Prior knowledge of which tapered_op has ground state
the_tapered_op = tapered_ops[smallest_idx][1]
the_coeff = tapered_ops[smallest_idx][0]
optimizer = SLSQP(maxiter=1000)
init_state = HartreeFock(
num_qubits=the_tapered_op.num_qubits,
num_orbitals=self.core._molecule_info['num_orbitals'],
qubit_mapping=self.core._qubit_mapping,
two_qubit_reduction=self.core._two_qubit_reduction,
num_particles=self.core._molecule_info['num_particles'],
sq_list=self.sq_list)
var_form = UCCSD(
num_qubits=the_tapered_op.num_qubits,
depth=1,
num_orbitals=self.core._molecule_info['num_orbitals'],
num_particles=self.core._molecule_info['num_particles'],
active_occupied=None,
active_unoccupied=None,
initial_state=init_state,
qubit_mapping=self.core._qubit_mapping,
two_qubit_reduction=self.core._two_qubit_reduction,
num_time_slices=1,
cliffords=self.cliffords,
sq_list=self.sq_list,
tapering_values=the_coeff,
symmetries=self.symmetries)
algo = VQE(the_tapered_op, var_form, optimizer, 'matrix')
backend = BasicAer.get_backend('statevector_simulator')
quantum_instance = QuantumInstance(backend=backend)
algo_result = algo.run(quantum_instance)
lines, result = self.core.process_algorithm_result(algo_result)
self.assertAlmostEqual(result['energy'],
self.reference_energy,
places=6)
def _build_hopping_operator(self, index):
def check_commutativity(op_1, op_2):
com = op_1 * op_2 - op_2 * op_1
com.zeros_coeff_elimination()
return True if com.is_empty() else False
two_d_zeros = np.zeros((self._num_orbitals, self._num_orbitals))
four_d_zeros = np.zeros((self._num_orbitals, self._num_orbitals,
self._num_orbitals, self._num_orbitals))
dummpy_fer_op = FermionicOperator(h1=two_d_zeros, h2=four_d_zeros)
h1 = two_d_zeros.copy()
h2 = four_d_zeros.copy()
if len(index) == 2:
i, j = index
h1[i, j] = 1.0
h1[j, i] = -1.0
elif len(index) == 4:
i, j, k, m = index
h2[i, j, k, m] = 1.0
h2[m, k, j, i] = -1.0
dummpy_fer_op.h1 = h1
dummpy_fer_op.h2 = h2
qubit_op = dummpy_fer_op.mapping(self._qubit_mapping)
qubit_op = qubit_op.two_qubit_reduced_operator(
self._num_particles) if self._two_qubit_reduction else qubit_op
if self._qubit_tapering:
for symmetry in self._symmetries:
symmetry_op = Operator(paulis=[[1.0, symmetry]])
symm_commuting = check_commutativity(symmetry_op, qubit_op)
if not symm_commuting:
break
if self._qubit_tapering:
if symm_commuting:
qubit_op = Operator.qubit_tapering(qubit_op, self._cliffords,
self._sq_list,
self._tapering_values)
else:
qubit_op = None
if qubit_op is None:
logger.debug('excitation ({}) is skipped since it is not commuted '
'with symmetries'.format(','.join(
[str(x) for x in index])))
return qubit_op
def _build_hopping_operator(index, num_orbitals, num_particles,
qubit_mapping, two_qubit_reduction,
qubit_tapering, symmetries, cliffords, sq_list,
tapering_values):
def check_commutativity(op_1, op_2):
com = op_1 * op_2 - op_2 * op_1
com.zeros_coeff_elimination()
return True if com.is_empty() else False
h1 = np.zeros((num_orbitals, num_orbitals))
h2 = np.zeros((num_orbitals, num_orbitals, num_orbitals, num_orbitals))
if len(index) == 2:
i, j = index
h1[i, j] = 1.0
h1[j, i] = -1.0
elif len(index) == 4:
i, j, k, m = index
h2[i, j, k, m] = 1.0
h2[m, k, j, i] = -1.0
dummpy_fer_op = FermionicOperator(h1=h1, h2=h2)
qubit_op = dummpy_fer_op.mapping(qubit_mapping, num_workers=1)
qubit_op = qubit_op.two_qubit_reduced_operator(num_particles) \
if two_qubit_reduction else qubit_op
if qubit_tapering:
for symmetry in symmetries:
symmetry_op = Operator(paulis=[[1.0, symmetry]])
symm_commuting = check_commutativity(symmetry_op, qubit_op)
if not symm_commuting:
break
if qubit_tapering:
if symm_commuting:
qubit_op = Operator.qubit_tapering(qubit_op, cliffords,
sq_list, tapering_values)
else:
qubit_op = None
if qubit_op is None:
logger.debug('Excitation ({}) is skipped since it is not commuted '
'with symmetries'.format(','.join(
[str(x) for x in index])))
return index, qubit_op
