def test_bk_jw_majoranas(self):
# Check if the Majorana operators have the same spectrum
# irrespectively of the transform.
n_qubits = 7
a = FermionOperator(((1, 0), ))
a_dag = FermionOperator(((1, 1), ))
c = a + a_dag
d = 1j * (a_dag - a)
c_spins = [jordan_wigner(c), bravyi_kitaev(c)]
d_spins = [jordan_wigner(d), bravyi_kitaev(d)]
c_sparse = [
get_sparse_operator(c_spins[0]),
get_sparse_operator(c_spins[1])
]
d_sparse = [
get_sparse_operator(d_spins[0]),
get_sparse_operator(d_spins[1])
]
c_spectrum = [eigenspectrum(c_spins[0]), eigenspectrum(c_spins[1])]
d_spectrum = [eigenspectrum(d_spins[0]), eigenspectrum(d_spins[1])]
self.assertAlmostEqual(
0., numpy.amax(numpy.absolute(d_spectrum[0] - d_spectrum[1])))
def __init__(self, qubit_1, qubit_2, system_n_qubits=None, encoding='jw'):
self.spin_complement = True
self.qubits = [[qubit_1], [qubit_2]]
self.complement_qubits = [
self.spin_complement_orbitals([qubit_1]),
self.spin_complement_orbitals([qubit_2])
]
fermi_operator_1 = FermionOperator('[{1}^ {0}] - [{0}^ {1}]'.format(
qubit_2, qubit_1))
if encoding == 'jw':
excitations_generators = [jordan_wigner(fermi_operator_1)]
else:
assert encoding == 'bk'
excitations_generators = [bravyi_kitaev(fermi_operator_1)]
if {*self.qubits[0], *self.qubits[1]} != {*self.complement_qubits[0], *self.complement_qubits[1]} and \
{*self.qubits[0], *self.qubits[1]} != {*self.complement_qubits[1], *self.complement_qubits[0]}:
fermi_operator_2 = FermionOperator(
'[{1}^ {0}] - [{0}^ {1}]'.format(self.complement_qubits[1][0],
self.complement_qubits[0][0]))
if encoding == 'jw':
excitations_generators = [jordan_wigner(fermi_operator_2)]
else:
assert encoding == 'bk'
excitations_generators = [bravyi_kitaev(fermi_operator_2)]
super(SpinCompSFExc, self).\
__init__(element='spin_s_f_exc_{}_{}'.format(qubit_2, qubit_1), order=1, n_var_parameters=1,
excitations_generators=excitations_generators, system_n_qubits=system_n_qubits)
def test_bravyi_kitaev_transform(self):
# Check that the QubitOperators are two-term.
lowering = bravyi_kitaev(FermionOperator(((3, 0),)))
raising = bravyi_kitaev(FermionOperator(((3, 1),)))
self.assertEqual(len(raising.terms), 2)
self.assertEqual(len(lowering.terms), 2)
# Test the locality invariant for N=2^d qubits
# (c_j majorana is always log2N+1 local on qubits)
n_qubits = 16
invariant = numpy.log2(n_qubits) + 1
for index in range(n_qubits):
operator = bravyi_kitaev(FermionOperator(((index, 0),)), n_qubits)
qubit_terms = operator.terms.items() # Get the majorana terms.
for item in qubit_terms:
coeff = item[1]
# Identify the c majorana terms by real
# coefficients and check their length.
if not isinstance(coeff, complex):
self.assertEqual(len(item[0]), invariant)
# Hardcoded coefficient test on 16 qubits
lowering = bravyi_kitaev(FermionOperator(((9, 0),)), n_qubits)
raising = bravyi_kitaev(FermionOperator(((9, 1),)), n_qubits)
correct_operators_c = ((7, 'Z'), (8, 'Z'), (9, 'X'),
(11, 'X'), (15, 'X'))
correct_operators_d = ((7, 'Z'), (9, 'Y'), (11, 'X'), (15, 'X'))
self.assertEqual(lowering.terms[correct_operators_c], 0.5)
self.assertEqual(lowering.terms[correct_operators_d], 0.5j)
self.assertEqual(raising.terms[correct_operators_d], -0.5j)
self.assertEqual(raising.terms[correct_operators_c], 0.5)
def test_hermitian_conjugated_qubit_op_consistency(self):
"""Some consistency checks for conjugating QubitOperators."""
ferm_op = (FermionOperator('1^ 2') + FermionOperator('2 3 4') +
FermionOperator('2^ 7 9 11^'))
# Check that hermitian conjugation commutes with transforms
self.assertEqual(jordan_wigner(hermitian_conjugated(ferm_op)),
hermitian_conjugated(jordan_wigner(ferm_op)))
self.assertEqual(bravyi_kitaev(hermitian_conjugated(ferm_op)),
hermitian_conjugated(bravyi_kitaev(ferm_op)))
def get_qubit_hamiltonian(mol,
geometry,
basis,
charge=0,
multiplicity=1,
qubit_transf='bk'):
'''
Generating qubit hamiltonina of the given molecules with specified geometry, basis sets, charge and multiplicity
Give its qubit form using specified transformation
'''
g = get_molecular_data(mol, geometry)
mol = MolecularData(g, basis, multiplicity, charge)
mol = run_pyscf(mol)
ham = mol.get_molecular_hamiltonian()
hamf = get_fermion_operator(ham)
if qubit_transf == 'bk':
hamq = bravyi_kitaev(hamf)
elif qubit_transf == 'jw':
hamq = jordan_wigner(hamf)
else:
raise (ValueError(qubit_transf, 'Unknown transformation specified'))
return hamq
def decompose_hamiltonian(mol_name,
hf_data,
mapping="jordan_wigner",
docc_mo_indices=None,
active_mo_indices=None):
r"""Decomposes the electronic Hamiltonian into a linear combination of Pauli operators using
OpenFermion tools.
**Example usage:**
>>> decompose_hamiltonian('h2', './pyscf/sto-3g/', mapping='bravyi_kitaev')
(-0.04207897696293986+0j) [] + (0.04475014401986122+0j) [X0 Z1 X2] +
(0.04475014401986122+0j) [X0 Z1 X2 Z3] +(0.04475014401986122+0j) [Y0 Z1 Y2] +
(0.04475014401986122+0j) [Y0 Z1 Y2 Z3] +(0.17771287459806262+0j) [Z0] +
(0.17771287459806265+0j) [Z0 Z1] +(0.1676831945625423+0j) [Z0 Z1 Z2] +
(0.1676831945625423+0j) [Z0 Z1 Z2 Z3] +(0.12293305054268105+0j) [Z0 Z2] +
(0.12293305054268105+0j) [Z0 Z2 Z3] +(0.1705973832722409+0j) [Z1] +
(-0.2427428049645989+0j) [Z1 Z2 Z3] +(0.1762764080276107+0j) [Z1 Z3] +
(-0.2427428049645989+0j) [Z2]
Args:
mol_name (str): name of the molecule
hf_data (str): path to the directory containing the file with the Hartree-Fock
electronic structure
mapping (str): optional argument to specify the fermion-to-qubit mapping
Input values can be ``'jordan_wigner'`` or ``'bravyi_kitaev'``
docc_mo_indices (list): indices of doubly-occupied molecular orbitals, i.e.,
the orbitals that are not correlated in the many-body wave function
active_mo_indices (list): indices of active molecular orbitals, i.e., the orbitals used to
build the correlated many-body wave function
Returns:
transformed_operator: instance of the QubitOperator class representing the electronic
Hamiltonian
"""
# loading HF data from a hdf5 file
molecule = MolecularData(
filename=os.path.join(hf_data.strip(), mol_name.strip()))
# getting the terms entering the second-quantized Hamiltonian
terms_molecular_hamiltonian = molecule.get_molecular_hamiltonian(
occupied_indices=docc_mo_indices, active_indices=active_mo_indices)
# generating the fermionic Hamiltonian
fermionic_hamiltonian = get_fermion_operator(terms_molecular_hamiltonian)
mapping = mapping.strip().lower()
if mapping not in ("jordan_wigner", "bravyi_kitaev"):
raise TypeError(
"The '{}' transformation is not available. \n "
"Please set 'mapping' to 'jordan_wigner' or 'bravyi_kitaev'.".
format(mapping))
# fermionic-to-qubit transformation of the Hamiltonian
if mapping == "bravyi_kitaev":
return bravyi_kitaev(fermionic_hamiltonian)
return jordan_wigner(fermionic_hamiltonian)
def __init__(self,
qubit_pair_1,
qubit_pair_2,
system_n_qubits=None,
encoding='jw'):
self.spin_complement = False
qubit_pair_1.sort()
qubit_pair_2.sort()
assert len(qubit_pair_1) == 2
assert len(qubit_pair_2) == 2
self.qubits = [qubit_pair_1, qubit_pair_2]
fermi_operator = FermionOperator(
'[{2}^ {3}^ {0} {1}] - [{0}^ {1}^ {2} {3}]'.format(
self.qubits[0][0], self.qubits[0][1], self.qubits[1][0],
self.qubits[1][1]))
if encoding == 'jw':
excitation_generator = jordan_wigner(fermi_operator)
else:
assert encoding == 'bk'
excitation_generator = bravyi_kitaev(fermi_operator)
super(DFExc, self).\
__init__(element='d_f_exc_{}_{}'.format(qubit_pair_1, qubit_pair_2), order=2, n_var_parameters=1,
excitations_generators=[excitation_generator], system_n_qubits=system_n_qubits)
def decompose(hf_file, mapping="jordan_wigner", core=None, active=None):
r"""Decomposes the molecular Hamiltonian into a linear combination of Pauli operators using
OpenFermion tools.
This function uses OpenFermion functions to build the second-quantized electronic Hamiltonian
of the molecule and map it to the Pauli basis using the Jordan-Wigner or Bravyi-Kitaev
transformation.
Args:
hf_file (str): absolute path to the hdf5-formatted file with the
Hartree-Fock electronic structure
mapping (str): Specifies the transformation to map the fermionic Hamiltonian to the
Pauli basis. Input values can be ``'jordan_wigner'`` or ``'bravyi_kitaev'``.
core (list): indices of core orbitals, i.e., the orbitals that are
not correlated in the many-body wave function
active (list): indices of active orbitals, i.e., the orbitals used to
build the correlated many-body wave function
Returns:
QubitOperator: an instance of OpenFermion's ``QubitOperator``
**Example**
>>> decompose('./pyscf/sto-3g/h2', mapping='bravyi_kitaev')
(-0.04207897696293986+0j) [] + (0.04475014401986122+0j) [X0 Z1 X2] +
(0.04475014401986122+0j) [X0 Z1 X2 Z3] +(0.04475014401986122+0j) [Y0 Z1 Y2] +
(0.04475014401986122+0j) [Y0 Z1 Y2 Z3] +(0.17771287459806262+0j) [Z0] +
(0.17771287459806265+0j) [Z0 Z1] +(0.1676831945625423+0j) [Z0 Z1 Z2] +
(0.1676831945625423+0j) [Z0 Z1 Z2 Z3] +(0.12293305054268105+0j) [Z0 Z2] +
(0.12293305054268105+0j) [Z0 Z2 Z3] +(0.1705973832722409+0j) [Z1] +
(-0.2427428049645989+0j) [Z1 Z2 Z3] +(0.1762764080276107+0j) [Z1 Z3] +
(-0.2427428049645989+0j) [Z2]
"""
# loading HF data from the hdf5 file
molecule = MolecularData(filename=hf_file.strip())
# getting the terms entering the second-quantized Hamiltonian
terms_molecular_hamiltonian = molecule.get_molecular_hamiltonian(
occupied_indices=core, active_indices=active
)
# generating the fermionic Hamiltonian
fermionic_hamiltonian = get_fermion_operator(terms_molecular_hamiltonian)
mapping = mapping.strip().lower()
if mapping not in ("jordan_wigner", "bravyi_kitaev"):
raise TypeError(
"The '{}' transformation is not available. \n "
"Please set 'mapping' to 'jordan_wigner' or 'bravyi_kitaev'.".format(mapping)
)
# fermionic-to-qubit transformation of the Hamiltonian
if mapping == "bravyi_kitaev":
return bravyi_kitaev(fermionic_hamiltonian)
return jordan_wigner(fermionic_hamiltonian)
def test_bravyi_kitaev(self):
hamiltonian, gs_energy = lih_hamiltonian()
code = bravyi_kitaev_code(4)
qubit_hamiltonian = binary_code_transform(hamiltonian, code)
self.assertAlmostEqual(gs_energy, eigenspectrum(qubit_hamiltonian)[0])
qubit_spectrum = eigenspectrum(qubit_hamiltonian)
fenwick_spectrum = eigenspectrum(bravyi_kitaev(hamiltonian))
for eigen_idx, eigenvalue in enumerate(qubit_spectrum):
self.assertAlmostEqual(eigenvalue, fenwick_spectrum[eigen_idx])
def get_BK_ham(distance, basis="sto-3g", multiplicity=1, charge=1):
geometry = [["He", [0, 0, 0]], ["H", [0, 0, distance]]]
description = str(distance)
molecule = MolecularData(geometry, basis, multiplicity, charge,
description)
molecule = run_pyscf(molecule, run_fci=1)
bk_hamiltonian = get_sparse_operator(
bravyi_kitaev(
get_fermion_operator(molecule.get_molecular_hamiltonian())))
return bk_hamiltonian
def get_ground_energy(interaction_hamil, numLayer):
fermionop_hamil = FermionOperator()
for key in interaction_hamil:
value = interaction_hamil[key]
fermionop_hamil += FermionOperator(term=key, coefficient=value)
qubitop_hamil = bravyi_kitaev(fermionop_hamil)
pauliop_hamil = qubitop_to_pyquilpauli(qubitop_hamil)
return solve_vqe(pauliop_hamil, numLayer)
def __init__(self,
qubit_pair_1,
qubit_pair_2,
system_n_qubits=None,
encoding='jw'):
self.spin_complement = True
assert len(qubit_pair_1) == 2
assert len(qubit_pair_2) == 2
self.qubits = [qubit_pair_1, qubit_pair_2]
self.complement_qubits = [
self.spin_complement_orbitals(qubit_pair_1),
self.spin_complement_orbitals(qubit_pair_2)
]
fermi_operator_1 = FermionOperator(
'[{2}^ {3}^ {0} {1}] - [{0}^ {1}^ {2} {3}]'.format(
*self.qubits[0], *self.qubits[1]))
if encoding == 'jw':
excitations_generators = [jordan_wigner(fermi_operator_1)]
else:
assert encoding == 'bk'
excitations_generators = [bravyi_kitaev(fermi_operator_1)]
if [set(self.qubits[0]), set(self.qubits[1])] != [set(self.complement_qubits[0]), set(self.complement_qubits[1])] and \
[set(self.qubits[0]), set(self.qubits[1])] != [set(self.complement_qubits[1]), set(self.complement_qubits[0])]:
fermi_operator_2 = FermionOperator(
'[{2}^ {3}^ {0} {1}] - [{0}^ {1}^ {2} {3}]'.format(
*self.complement_qubits[0], *self.complement_qubits[1]))
if encoding == 'jw':
excitations_generators = [jordan_wigner(fermi_operator_2)]
else:
assert encoding == 'bk'
excitations_generators = [bravyi_kitaev(fermi_operator_2)]
super(SpinCompDFExc, self).\
__init__(element='spin_d_f_exc_{}_{}'.format(qubit_pair_1, qubit_pair_2), order=2, n_var_parameters=1,
system_n_qubits=system_n_qubits, excitations_generators=excitations_generators)
def get_qubit_hamiltonian(g, basis, charge=0, spin=1, qubit_transf='jw'):
## Create OpenFermion molecule
#mol = gto.Mole()
#mol.atom = g
#mol.basis = basis
#mol.spin = spin
#mol.charge = charge
#mol.symmetry = False
##mol.max_memory = 1024
#mol.build()
multiplicity = spin + 1 # spin here is 2S ?
mol = MolecularData(g, basis, multiplicity, charge)
#mol.load()
# Convert to PySCF molecule and run SCF
print("Running run_pyscf...")
print(f"Time: {time()}")
print("=" * 20)
mol = run_pyscf(mol)
# Freeze some orbitals?
occupied_indices = range(183)
active_indices = range(183, 183+5)
# Get Hamiltonian
print("Running get_molecular_hamiltonian...")
print(f"Time: {time()}")
print("=" * 20)
ham = mol.get_molecular_hamiltonian(
occupied_indices=occupied_indices,
active_indices=active_indices)
import pdb; pdb.set_trace()
print("Running get_fermion_operator...")
print(f"Time: {time()}")
print("=" * 20)
hamf = get_fermion_operator(ham)
print(f"Running {qubit_transf}...")
print(f"Time: {time()}")
print("=" * 20)
if qubit_transf == 'bk':
hamq = bravyi_kitaev(hamf)
elif qubit_transf == 'jw':
hamq = jordan_wigner(hamf)
else:
raise(ValueError(qubit_transf, 'Unknown transformation specified'))
return remove_complex(hamq)
def full_ham_terms(spacing,dead_space = range(1),active_space = range(1,4)):
molecule=molecule_data(spacing)
molecular_hamiltonian = molecule.get_molecular_hamiltonian(
occupied_indices=dead_space,
active_indices=active_space)
fermion_hamiltonian = get_fermion_operator(molecular_hamiltonian)
qubit_hamiltonian = bravyi_kitaev(fermion_hamiltonian)
qubit_hamiltonian.compress()
terms_dict=qubit_hamiltonian.terms
return terms_dict
def test_bk_jw_hopping_operator(self):
# Check if the spectrum fits for a single hoppping operator
ho = FermionOperator(((1, 1), (4, 0))) + FermionOperator(
((4, 1), (1, 0)))
jw_ho = jordan_wigner(ho)
bk_ho = bravyi_kitaev(ho)
# Diagonalize and make sure the spectra are the same.
jw_spectrum = eigenspectrum(jw_ho)
bk_spectrum = eigenspectrum(bk_ho)
self.assertAlmostEqual(0., numpy.amax(
numpy.absolute(jw_spectrum - bk_spectrum)))
def test_bk_jw_number_operator(self):
# Check if number operator has the same spectrum in both
# BK and JW representations
n = number_operator(1, 0)
jw_n = jordan_wigner(n)
bk_n = bravyi_kitaev(n)
# Diagonalize and make sure the spectra are the same.
jw_spectrum = eigenspectrum(jw_n)
bk_spectrum = eigenspectrum(bk_n)
self.assertAlmostEqual(0., numpy.amax(
numpy.absolute(jw_spectrum - bk_spectrum)))
def test_bravyi_kitaev_transform_sympy(self):
# Check that the QubitOperators are two-term.
coeff = sympy.Symbol('x')
# Hardcoded coefficient test on 16 qubits
n_qubits = 16
lowering = bravyi_kitaev(FermionOperator(((9, 0), )) * coeff, n_qubits)
raising = bravyi_kitaev(FermionOperator(((9, 1), )) * coeff, n_qubits)
sum_lr = bravyi_kitaev(
FermionOperator(((9, 0), )) * coeff + FermionOperator(
((9, 1), )) * coeff, n_qubits)
correct_operators_c = ((7, 'Z'), (8, 'Z'), (9, 'X'), (11, 'X'), (15,
'X'))
correct_operators_d = ((7, 'Z'), (9, 'Y'), (11, 'X'), (15, 'X'))
self.assertEqual(lowering.terms[correct_operators_c], 0.5 * coeff)
self.assertEqual(lowering.terms[correct_operators_d], 0.5j * coeff)
self.assertEqual(raising.terms[correct_operators_d], -0.5j * coeff)
self.assertEqual(raising.terms[correct_operators_c], 0.5 * coeff)
self.assertEqual(len(sum_lr.terms), 1)
sum_lr_correct = QubitOperator(correct_operators_c, coeff)
self.assertEqual(sum_lr, sum_lr_correct)
def test_bk_jw_number_operator_scaled(self):
# Check if number operator has the same spectrum in both
# JW and BK representations
n_qubits = 1
n = number_operator(n_qubits, 0, coefficient=2) # eigenspectrum (0,2)
jw_n = jordan_wigner(n)
bk_n = bravyi_kitaev(n)
# Diagonalize and make sure the spectra are the same.
jw_spectrum = eigenspectrum(jw_n)
bk_spectrum = eigenspectrum(bk_n)
self.assertAlmostEqual(0., numpy.amax(
numpy.absolute(jw_spectrum - bk_spectrum)))
def test_bk_jw_integration(self):
# This is a legacy test, which was a minimal failing example when
# optimization for hermitian operators was used.
# Minimal failing example:
fo = FermionOperator(((3, 1),))
jw = jordan_wigner(fo)
bk = bravyi_kitaev(fo)
jw_spectrum = eigenspectrum(jw)
bk_spectrum = eigenspectrum(bk)
self.assertAlmostEqual(0., numpy.amax(numpy.absolute(jw_spectrum -
bk_spectrum)))
def __init__(self, qubit_1, qubit_2, system_n_qubits=None, encoding='jw'):
self.spin_complement = False
self.qubits = [[qubit_1], [qubit_2]]
fermi_operator = FermionOperator('[{1}^ {0}] - [{0}^ {1}]'.format(
self.qubits[1][0], self.qubits[0][0]))
if encoding == 'jw':
excitation_generator = jordan_wigner(fermi_operator)
else:
assert encoding == 'bk'
excitation_generator = bravyi_kitaev(fermi_operator)
super(SFExc, self).\
__init__(element='s_f_exc_{}_{}'.format(qubit_1, qubit_2), order=1, n_var_parameters=1,
excitations_generators=[excitation_generator], system_n_qubits=system_n_qubits)
def load_and_transform(filename, orbitals, transform):
# Load data
print('--- loading molecule ---')
molecule = MolecularData(filename=filename)
print('filename: {}'.format(molecule.filename))
#print('n_atoms: {}'.format(molecule.n_atoms))
#print('n_electrons: {}'.format(molecule.n_electrons))
#print('n_orbitals: {}'.format(molecule.n_orbitals))
#print('Canonical Orbitals: {}'.format(molecule.canonical_orbitals))
#print('n_qubits: {}'.format(molecule.n_qubits))
# get the Hamiltonian for a specific choice of active space
# set the Hamiltonian parameters
occupied_orbitals, active_orbitals = orbitals
molecular_hamiltonian = molecule.get_molecular_hamiltonian(
occupied_indices=range(occupied_orbitals),
active_indices=range(active_orbitals))
# map the operator to fermions and then qubits
fermion_hamiltonian = get_fermion_operator(molecular_hamiltonian)
# get interaction operator
interaction_hamiltonian = get_interaction_operator(fermion_hamiltonian)
if transform is 'JW':
qubit_h = jordan_wigner(fermion_hamiltonian)
qubit_h.compress()
elif transform is 'BK':
qubit_h = bravyi_kitaev(fermion_hamiltonian)
qubit_h.compress()
elif transform is 'BKSF':
qubit_h = bravyi_kitaev_fast(interaction_hamiltonian)
qubit_h.compress()
elif transform is 'BKT':
qubit_h = bravyi_kitaev_tree(fermion_hamiltonian)
qubit_h.compress()
elif transform is 'PC':
qubit_h = binary_code_transform(fermion_hamiltonian,
parity_code(2 * active_orbitals))
qubit_h.compress()
else:
print('ERROR: Unrecognized qubit transformation: {}'.format(transform))
sys.exit(2)
return qubit_h
def test_bk_jw_number_operators(self):
# Check if a number operator has the same spectrum in both
# JW and BK representations
n_qubits = 2
n1 = number_operator(n_qubits, 0)
n2 = number_operator(n_qubits, 1)
n = n1 + n2
jw_n = jordan_wigner(n)
bk_n = bravyi_kitaev(n)
# Diagonalize and make sure the spectra are the same.
jw_spectrum = eigenspectrum(jw_n)
bk_spectrum = eigenspectrum(bk_n)
self.assertAlmostEqual(0., numpy.amax(
numpy.absolute(jw_spectrum - bk_spectrum)))
def test_bk_jw_integration_original(self):
# This is a legacy test, which was an example proposed by Ryan,
# failing when optimization for hermitian operators was used.
fermion_operator = FermionOperator(((3, 1), (2, 1), (1, 0), (0, 0)),
-4.3)
fermion_operator += FermionOperator(((3, 1), (1, 0)), 8.17)
fermion_operator += 3.2 * FermionOperator()
# Map to qubits and compare matrix versions.
jw_qubit_operator = jordan_wigner(fermion_operator)
bk_qubit_operator = bravyi_kitaev(fermion_operator)
# Diagonalize and make sure the spectra are the same.
jw_spectrum = eigenspectrum(jw_qubit_operator)
bk_spectrum = eigenspectrum(bk_qubit_operator)
self.assertAlmostEqual(0., numpy.amax(numpy.absolute(jw_spectrum -
bk_spectrum)), places=5)
def get_molecular_Hamiltonian(geometry=[('H', (0.0, 0.0, 0.0)),
('H', (0.0, 0.0, 0.7414))],
basis='sto-3g',
multiplicity=1,
charge=0):
# Perform electronic structure calculations and obtain Hamiltonian as an InteractionOperator
hamiltonian = ofpyscf.generate_molecular_hamiltonian(
geometry, basis, multiplicity, charge)
# Convert to a FermionOperator
hamiltonian_ferm_op = of.get_fermion_operator(hamiltonian)
mol_qubit_hamiltonianBK = bravyi_kitaev(
hamiltonian_ferm_op
) # JW is exponential in the maximum locality of the original FermionOperator.
mol_matrix = get_sparse_operator(mol_qubit_hamiltonianBK).todense()
return mol_matrix
def majorana_to_pauli_dict(majorana_list, qubit_mapping='jw'):
"""
Generates a dictionary from Majorana operator indices (ordered tuples) to
its Pauli string representation under a given fermion-to-qubit mapping.
Does not keep track of phases in front of the operators, since we always
assume the convention
Majorana operator = (-i)^k * \gamma_1 ... \gamma_{2k}.
Parameters
----------
majorana_list : iterable
An iterable of Majorana tuples.
qubit_mapping : str, optional
The chosen fermion-to-qubit mapping, Jordan-Wigner ('jw') or Bravyi-
Kitaev ('bk'). The default is 'jw'.
Raises
------
NotImplementedError
If mappings other than Jordan-Wigner or Bravyi-Kitaev are specified.
Returns
-------
majorana_to_pauli : dict
Dictionary which maps between the Majorana and Pauli representations.
"""
majorana_to_pauli = {}
for majorana in majorana_list:
if qubit_mapping == 'jw':
op = jordan_wigner(MajoranaOperator(mu))
elif qubit_mapping == 'bk':
op = bravyi_kitaev(MajoranaOperator(mu))
else:
raise NotImplementedError(
'Only jw and bk mappings currently supported.')
majorana_to_pauli[majorana] = next(iter(op.terms))
return majorana_to_pauli
def load_and_transform(filename, orbitals, transform):
# Load data
print('--- Loading molecule ---')
molecule = MolecularData(filename=filename)
molecule.load()
print('filename: {}'.format(molecule.filename))
print('n_atoms: {}'.format(molecule.n_atoms))
print('n_electrons: {}'.format(molecule.n_electrons))
print('n_orbitals: {}'.format(molecule.n_orbitals))
#print('Canonical Orbitals: {}'.format(molecule.canonical_orbitals))
print('n_qubits: {}'.format(molecule.n_qubits))
# Get the Hamiltonian in an active space.
# Set Hamiltonian parameters.
occupied_orbitals, active_orbitals = orbitals
molecular_hamiltonian = molecule.get_molecular_hamiltonian(
occupied_indices=range(occupied_orbitals),
active_indices=range(active_orbitals))
# Map operator to fermions and qubits.
fermion_hamiltonian = get_fermion_operator(molecular_hamiltonian)
#print('Fermionic Hamiltonian is:\n{}'.format(fermion_hamiltonian))
if transform is 'JW':
qubit_h = jordan_wigner(fermion_hamiltonian)
qubit_h.compress()
print('\nJordan-Wigner Hamiltonian:\n{}'.format(qubit_h))
elif transform is 'BK':
qubit_h = bravyi_kitaev(fermion_hamiltonian)
qubit_h.compress()
print('\nBravyi-Kitaev Hamiltonian is:\n{}'.format(qubit_h))
else:
print('ERROR: Unrecognized qubit transformation: {}'.format(transform))
sys.exit(2)
return qubit_h
def test_bk_n_qubits_too_small(self):
with self.assertRaises(ValueError):
bravyi_kitaev(FermionOperator('2^ 3^ 5 0'), n_qubits=4)
with self.assertRaises(ValueError):
bravyi_kitaev(MajoranaOperator((2, 3, 9, 0)), n_qubits=4)
def test_bk_identity(self):
self.assertTrue(bravyi_kitaev(FermionOperator(())) ==
QubitOperator(()))
def test_bravyi_kitaev_majorana_op_consistent():
op = (MajoranaOperator((1, 3, 4), 0.5)
+ MajoranaOperator((3, 7, 8, 9, 10, 12), 1.8)
+ MajoranaOperator((0, 4)))
assert bravyi_kitaev(op) == bravyi_kitaev(get_fermion_operator(op))
def test_bk_bad_type(self):
with self.assertRaises(TypeError):
bravyi_kitaev(QubitOperator())