def _build_single_hopping_operator(index, num_particles, num_orbitals, qubit_mapping,
two_qubit_reduction, z2_symmetries):
h_1 = np.zeros((num_orbitals, num_orbitals), dtype=complex)
h_2 = np.zeros((num_orbitals, num_orbitals, num_orbitals, num_orbitals), dtype=complex)
if len(index) == 2:
i, j = index
h_1[i, j] = 4.0
elif len(index) == 4:
i, j, k, m = index
h_2[i, j, k, m] = 16.0
fer_op = FermionicOperator(h_1, h_2)
qubit_op = fer_op.mapping(qubit_mapping)
if qubit_mapping == 'parity' and two_qubit_reduction:
qubit_op = Z2Symmetries.two_qubit_reduction(qubit_op, num_particles)
commutativities = []
if not z2_symmetries.is_empty():
for symmetry in z2_symmetries.symmetries:
symmetry_op = WeightedPauliOperator(paulis=[[1.0, symmetry]])
commuting = qubit_op.commute_with(symmetry_op)
anticommuting = qubit_op.anticommute_with(symmetry_op)
if commuting != anticommuting: # only one of them is True
if commuting:
commutativities.append(True)
elif anticommuting:
commutativities.append(False)
else:
raise AquaError("Symmetry {} is nor commute neither anti-commute "
"to exciting operator.".format(symmetry.to_label()))
return qubit_op, commutativities
def _build_hopping_operator(index, num_orbitals, num_particles, qubit_mapping,
two_qubit_reduction, z2_symmetries):
h_1 = np.zeros((num_orbitals, num_orbitals))
h_2 = np.zeros((num_orbitals, num_orbitals, num_orbitals, num_orbitals))
if len(index) == 2:
i, j = index
h_1[i, j] = 1.0
h_1[j, i] = -1.0
elif len(index) == 4:
i, j, k, m = index
h_2[i, j, k, m] = 1.0
h_2[m, k, j, i] = -1.0
dummpy_fer_op = FermionicOperator(h1=h_1, h2=h_2)
qubit_op = dummpy_fer_op.mapping(qubit_mapping)
if two_qubit_reduction:
qubit_op = Z2Symmetries.two_qubit_reduction(qubit_op, num_particles)
if not z2_symmetries.is_empty():
symm_commuting = True
for symmetry in z2_symmetries.symmetries:
symmetry_op = WeightedPauliOperator(paulis=[[1.0, symmetry]])
symm_commuting = qubit_op.commute_with(symmetry_op)
if not symm_commuting:
break
qubit_op = z2_symmetries.taper(qubit_op) if symm_commuting else None
if qubit_op is None:
logger.debug('Excitation (%s) is skipped since it is not commuted '
'with symmetries', ','.join([str(x) for x in index]))
return qubit_op, index
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
def _map_fermionic_operator_to_qubit(fer_op: FermionicOperator,
qubit_mapping: str,
num_particles: List[int],
two_qubit_reduction: bool) -> WeightedPauliOperator:
"""
Args:
fer_op: Fermionic Operator
qubit_mapping: fermionic to qubit mapping
num_particles: number of particles
two_qubit_reduction: two qubit reduction
Returns:
qubit operator
"""
qubit_op = fer_op.mapping(map_type=qubit_mapping, threshold=0.00000001)
if qubit_mapping == 'parity' and two_qubit_reduction:
qubit_op = Z2Symmetries.two_qubit_reduction(qubit_op, num_particles)
return qubit_op
def _build_hopping_operator(index,
num_orbitals,
num_particles,
qubit_mapping,
two_qubit_reduction,
z2_symmetries,
skip_commute_test=False):
"""
Builds a hopping operator given the list of indices (index) that is a single or a double
excitation.
Args:
index (list): a single or double excitation (e.g. double excitation [0,1,2,3] for a 4
spin-orbital system)
num_orbitals (int): number of spin-orbitals
num_particles (int): number of electrons
qubit_mapping (str): qubit mapping type
two_qubit_reduction (bool): reduce the number of qubits by 2 if
parity qubit mapping is used
z2_symmetries (Z2Symmetries): class that contains the symmetries
of hamiltonian for tapering
skip_commute_test (bool): when tapering excitation operators we test and exclude any
that do not commute with symmetries. This test can be skipped to
include all tapered excitation operators whether they commute
or not.
Returns:
WeightedPauliOperator: qubit_op
list: index
"""
h_1 = np.zeros((num_orbitals, num_orbitals))
h_2 = np.zeros(
(num_orbitals, num_orbitals, num_orbitals, num_orbitals))
if len(index) == 2:
i, j = index
h_1[i, j] = 1.0
h_1[j, i] = -1.0
elif len(index) == 4:
i, j, k, m = index
h_2[i, j, k, m] = 1.0
h_2[m, k, j, i] = -1.0
dummpy_fer_op = FermionicOperator(h1=h_1, h2=h_2)
qubit_op = dummpy_fer_op.mapping(qubit_mapping)
if two_qubit_reduction:
qubit_op = Z2Symmetries.two_qubit_reduction(
qubit_op, num_particles)
if not z2_symmetries.is_empty():
symm_commuting = True
for symmetry in z2_symmetries.symmetries:
symmetry_op = WeightedPauliOperator(paulis=[[1.0, symmetry]])
symm_commuting = qubit_op.commute_with(symmetry_op)
if not symm_commuting:
break
if not skip_commute_test:
qubit_op = z2_symmetries.taper(
qubit_op) if symm_commuting else None
else:
qubit_op = z2_symmetries.taper(qubit_op)
if qubit_op is None:
logger.debug(
'Excitation (%s) is skipped since it is not commuted '
'with symmetries', ','.join([str(x) for x in index]))
return qubit_op, index