def test_ffft_2d_4x4_logical_state(self):
system_size = 4
grid = Grid(dimensions=2, length=system_size, scale=1.0)
fermion_operator = FermionOperator('12^ 11^ 4^ 3^')
ffft_result = operator_2d_fft_with_reordering(
fermion_operator, system_size)
eng = MainEngine()
reg = eng.allocate_qureg(system_size ** 2)
X | reg[3]
X | reg[4]
X | reg[11]
X | reg[12]
ffft_2d(eng, reg, system_size)
eng.flush()
engine_wvfn = ordered_wavefunction(eng)
operator_wvfn = numpy.zeros(2 ** (system_size ** 2), dtype=complex)
for term in ffft_result.terms:
i = sum(2 ** site[0] for site in term)
operator_wvfn[i] = ffft_result.terms[term]
All(Measure) | reg
self.assertTrue(numpy.allclose(engine_wvfn, operator_wvfn))
def test_ffft_2d_4x4_equal_expectation_values(self):
system_size = 4
n_qubits = 16
grid = Grid(dimensions=2, length=system_size, scale=1.0)
dual_basis = jellium_model(grid, spinless=True, plane_wave=False)
ffft_result = operator_2d_fft_with_reordering(dual_basis, system_size)
jw_dual_basis = jordan_wigner(dual_basis)
jw_plane_wave = jordan_wigner(ffft_result)
# Do plane wave and dual basis calculations together.
pw_engine = MainEngine()
pw_wavefunction = pw_engine.allocate_qureg(system_size ** 2)
db_engine = MainEngine()
db_wavefunction = db_engine.allocate_qureg(system_size ** 2)
pw_engine.flush()
db_engine.flush()
# Choose random state.
state = numpy.zeros(2 ** n_qubits, dtype=complex)
for i in range(len(state)):
state[i] = (random.random() *
numpy.exp(1j * 2 * numpy.pi * random.random()))
state /= numpy.linalg.norm(state)
# Put randomly chosen state in the registers.
pw_engine.backend.set_wavefunction(state, pw_wavefunction)
db_engine.backend.set_wavefunction(state, db_wavefunction)
# Apply the FFFT to the dual basis wave function.
ffft_2d(db_engine, db_wavefunction, system_size)
# Flush the engine and compute expectation values and eigenvalues.
pw_engine.flush()
db_engine.flush()
plane_wave_expectation_value = (
pw_engine.backend.get_expectation_value(
jw_dual_basis, pw_wavefunction))
dual_basis_expectation_value = (
db_engine.backend.get_expectation_value(
jw_plane_wave, db_wavefunction))
All(Measure) | pw_wavefunction
All(Measure) | db_wavefunction
self.assertAlmostEqual(plane_wave_expectation_value,
dual_basis_expectation_value)