def test_bravyi_kitaev_fast_number_excitation_operator(self):
# using hydrogen Hamiltonian and introducing some number operator terms
constant = 0
one_body = numpy.zeros((4, 4))
one_body[(0, 0)] = .4
one_body[(1, 1)] = .5
one_body[(2, 2)] = .6
one_body[(3, 3)] = .7
two_body = self.molecular_hamiltonian.two_body_tensor
# initiating number operator terms for all the possible cases
two_body[(1, 2, 3, 1)] = 0.1
two_body[(1, 3, 2, 1)] = 0.1
two_body[(1, 2, 1, 3)] = 0.15
two_body[(3, 1, 2, 1)] = 0.15
two_body[(0, 2, 2, 1)] = 0.09
two_body[(1, 2, 2, 0)] = 0.09
two_body[(1, 2, 3, 2)] = 0.11
two_body[(2, 3, 2, 1)] = 0.11
two_body[(2, 2, 2, 2)] = 0.1
molecular_hamiltonian = InteractionOperator(constant, one_body,
two_body)
# comparing the eigenspectrum of Hamiltonian
n_qubits = count_qubits(molecular_hamiltonian)
bravyi_kitaev_fast_H = bksf.bravyi_kitaev_fast(molecular_hamiltonian)
jw_H = jordan_wigner(molecular_hamiltonian)
bravyi_kitaev_fast_H_eig = eigenspectrum(bravyi_kitaev_fast_H)
jw_H_eig = eigenspectrum(jw_H)
bravyi_kitaev_fast_H_eig = bravyi_kitaev_fast_H_eig.round(5)
jw_H_eig = jw_H_eig.round(5)
evensector_H = 0
for i in range(numpy.size(jw_H_eig)):
if bool(
numpy.size(
numpy.where(jw_H_eig[i] == bravyi_kitaev_fast_H_eig))):
evensector_H += 1
# comparing eigenspectrum of number operator
bravyi_kitaev_fast_n = bksf.number_operator(molecular_hamiltonian)
jw_n = QubitOperator()
n_qubits = count_qubits(molecular_hamiltonian)
for i in range(n_qubits):
jw_n += jordan_wigner_one_body(i, i)
jw_eig_spec = eigenspectrum(jw_n)
bravyi_kitaev_fast_eig_spec = eigenspectrum(bravyi_kitaev_fast_n)
evensector_n = 0
for i in range(numpy.size(jw_eig_spec)):
if bool(
numpy.size(
numpy.where(
jw_eig_spec[i] == bravyi_kitaev_fast_eig_spec))):
evensector_n += 1
self.assertEqual(evensector_H, 2**(n_qubits - 1))
self.assertEqual(evensector_n, 2**(n_qubits - 1))
def test_bravyi_kitaev_fast_jw_hamiltonian(self):
# make sure half of the jordan-wigner Hamiltonian eigenspectrum can
# be found in bksf Hamiltonian eigenspectrum.
n_qubits = count_qubits(self.molecular_hamiltonian)
bravyi_kitaev_fast_H = bksf.bravyi_kitaev_fast(
self.molecular_hamiltonian)
jw_H = jordan_wigner(self.molecular_hamiltonian)
bravyi_kitaev_fast_H_eig = eigenspectrum(bravyi_kitaev_fast_H)
jw_H_eig = eigenspectrum(jw_H)
bravyi_kitaev_fast_H_eig = bravyi_kitaev_fast_H_eig.round(5)
jw_H_eig = jw_H_eig.round(5)
evensector = 0
for i in range(numpy.size(jw_H_eig)):
if bool(
numpy.size(
numpy.where(jw_H_eig[i] == bravyi_kitaev_fast_H_eig))):
evensector += 1
self.assertEqual(evensector, 2**(n_qubits - 1))
def test_bravyi_kitaev_fast_excitation_terms(self):
# Testing on-site and excitation terms in Hamiltonian
constant = 0
one_body = numpy.array([[1, 2, 0, 3], [2, 1, 2, 0], [0, 2, 1, 2.5],
[3, 0, 2.5, 1]])
# No Coloumb interaction
two_body = numpy.zeros((4, 4, 4, 4))
molecular_hamiltonian = InteractionOperator(constant, one_body,
two_body)
n_qubits = count_qubits(molecular_hamiltonian)
# comparing the eigenspectrum of Hamiltonian
bravyi_kitaev_fast_H = bksf.bravyi_kitaev_fast(molecular_hamiltonian)
jw_H = jordan_wigner(molecular_hamiltonian)
bravyi_kitaev_fast_H_eig = eigenspectrum(bravyi_kitaev_fast_H)
jw_H_eig = eigenspectrum(jw_H)
bravyi_kitaev_fast_H_eig = bravyi_kitaev_fast_H_eig.round(5)
jw_H_eig = jw_H_eig.round(5)
evensector_H = 0
for i in range(numpy.size(jw_H_eig)):
if bool(
numpy.size(
numpy.where(jw_H_eig[i] == bravyi_kitaev_fast_H_eig))):
evensector_H += 1
# comparing eigenspectrum of number operator
bravyi_kitaev_fast_n = bksf.number_operator(molecular_hamiltonian)
jw_n = QubitOperator()
n_qubits = count_qubits(molecular_hamiltonian)
for i in range(n_qubits):
jw_n += jordan_wigner_one_body(i, i)
jw_eig_spec = eigenspectrum(jw_n)
bravyi_kitaev_fast_eig_spec = eigenspectrum(bravyi_kitaev_fast_n)
evensector_n = 0
for i in range(numpy.size(jw_eig_spec)):
if bool(
numpy.size(
numpy.where(
jw_eig_spec[i] == bravyi_kitaev_fast_eig_spec))):
evensector_n += 1
self.assertEqual(evensector_H, 2**(n_qubits - 1))
self.assertEqual(evensector_n, 2**(n_qubits - 1))
def test_bad_input(self):
with self.assertRaises(TypeError):
bksf.bravyi_kitaev_fast(FermionOperator())