def test_iqpe(self, distance):
        """ iqpe test """
        self.log.debug('Testing End-to-End with IQPE on H2 with '
                       'inter-atomic distance %s.', distance)
        try:
            driver = PySCFDriver(atom='H .0 .0 .0; H .0 .0 {}'.format(distance),
                                 unit=UnitsType.ANGSTROM,
                                 charge=0,
                                 spin=0,
                                 basis='sto3g')
        except QiskitChemistryError:
            self.skipTest('PYSCF driver does not appear to be installed')
        molecule = driver.run()
        qubit_mapping = 'parity'
        fer_op = FermionicOperator(h1=molecule.one_body_integrals,
                                   h2=molecule.two_body_integrals)
        qubit_op = fer_op.mapping(map_type=qubit_mapping, threshold=1e-10)
        qubit_op = Z2Symmetries.two_qubit_reduction(qubit_op, 2)

        exact_eigensolver = ExactEigensolver(qubit_op, k=1)
        results = exact_eigensolver.run()
        reference_energy = results['energy']
        self.log.debug('The exact ground state energy is: %s', results['energy'])

        num_particles = molecule.num_alpha + molecule.num_beta
        two_qubit_reduction = True
        num_orbitals = qubit_op.num_qubits + (2 if two_qubit_reduction else 0)

        num_time_slices = 1
        num_iterations = 6
        state_in = HartreeFock(qubit_op.num_qubits, num_orbitals,
                               num_particles, qubit_mapping, two_qubit_reduction)
        iqpe = IQPE(qubit_op, state_in, num_time_slices, num_iterations,
                    expansion_mode='suzuki', expansion_order=2,
                    shallow_circuit_concat=True)
        backend = qiskit.BasicAer.get_backend('qasm_simulator')
        quantum_instance = QuantumInstance(backend, shots=100)

        result = iqpe.run(quantum_instance)

        self.log.debug('top result str label:     %s', result['top_measurement_label'])
        self.log.debug('top result in decimal:    %s', result['top_measurement_decimal'])
        self.log.debug('stretch:                  %s', result['stretch'])
        self.log.debug('translation:              %s', result['translation'])
        self.log.debug('final energy from QPE:    %s', result['energy'])
        self.log.debug('reference energy:         %s', reference_energy)
        self.log.debug('ref energy (transformed): %s',
                       (reference_energy + result['translation']) * result['stretch'])
        self.log.debug('ref binary str label:     %s', decimal_to_binary(
            (reference_energy + result['translation']) * result['stretch'],
            max_num_digits=num_iterations + 3,
            fractional_part_only=True
        ))

        np.testing.assert_approx_equal(result['energy'], reference_energy, significant=2)
    def test_iqpe(self, distance):
        self.algorithm = 'IQPE'
        self.log.debug('Testing End-to-End with IQPE on H2 with '
                       'inter-atomic distance {}.'.format(distance))
        try:
            driver = PySCFDriver(atom='H .0 .0 .0; H .0 .0 {}'.format(distance),
                                 unit=UnitsType.ANGSTROM,
                                 charge=0,
                                 spin=0,
                                 basis='sto3g')
        except QiskitChemistryError:
            self.skipTest('PYSCF driver does not appear to be installed')
        self.molecule = driver.run()
        qubit_mapping = 'parity'
        fer_op = FermionicOperator(h1=self.molecule.one_body_integrals, h2=self.molecule.two_body_integrals)
        self.qubit_op = fer_op.mapping(map_type=qubit_mapping, threshold=1e-10).two_qubit_reduced_operator(2)

        exact_eigensolver = ExactEigensolver(self.qubit_op, k=1)
        results = exact_eigensolver.run()
        self.reference_energy = results['energy']
        self.log.debug('The exact ground state energy is: {}'.format(results['energy']))

        num_particles = self.molecule.num_alpha + self.molecule.num_beta
        two_qubit_reduction = True
        num_orbitals = self.qubit_op.num_qubits + (2 if two_qubit_reduction else 0)

        num_time_slices = 50
        num_iterations = 12
        state_in = HartreeFock(self.qubit_op.num_qubits, num_orbitals,
                               num_particles, qubit_mapping, two_qubit_reduction)
        iqpe = IQPE(self.qubit_op, state_in, num_time_slices, num_iterations,
                    expansion_mode='suzuki', expansion_order=2,
                    shallow_circuit_concat=True)
        backend = qiskit.Aer.get_backend('qasm_simulator')
        run_config = RunConfig(shots=100, max_credits=10, memory=False)
        quantum_instance = QuantumInstance(backend, run_config, pass_manager=PassManager())

        result = iqpe.run(quantum_instance)

        self.log.debug('top result str label:     {}'.format(result['top_measurement_label']))
        self.log.debug('top result in decimal:    {}'.format(result['top_measurement_decimal']))
        self.log.debug('stretch:                  {}'.format(result['stretch']))
        self.log.debug('translation:              {}'.format(result['translation']))
        self.log.debug('final energy from QPE:    {}'.format(result['energy']))
        self.log.debug('reference energy:         {}'.format(self.reference_energy))
        self.log.debug('ref energy (transformed): {}'.format(
            (self.reference_energy + result['translation']) * result['stretch'])
        )
        self.log.debug('ref binary str label:     {}'.format(decimal_to_binary(
            (self.reference_energy + result['translation']) * result['stretch'],
            max_num_digits=num_iterations + 3,
            fractional_part_only=True
        )))

        np.testing.assert_approx_equal(result['energy'], self.reference_energy, significant=2)