def test_tapering_qubits_manual_input(self):
"""
Test taper_off_qubits function using LiH Hamiltonian.
Checks different qubits inputs to remove manually.
Test the lowest eigenvalue against the full Hamiltonian,
and the full spectrum between them.
"""
hamiltonian, spectrum = lih_hamiltonian()
qubit_hamiltonian = jordan_wigner(hamiltonian)
stab1 = QubitOperator('Z0 Z2', -1.0)
stab2 = QubitOperator('Z1 Z3', -1.0)
tapered_ham_0_3 = taper_off_qubits(qubit_hamiltonian, [stab1, stab2],
manual_input=True,
fixed_positions=[0, 3])
tapered_ham_2_1 = taper_off_qubits(qubit_hamiltonian, [stab1, stab2],
manual_input=True,
fixed_positions=[2, 1])
tapered_spectrum_0_3 = eigenspectrum(tapered_ham_0_3)
tapered_spectrum_2_1 = eigenspectrum(tapered_ham_2_1)
self.assertAlmostEqual(spectrum[0], tapered_spectrum_0_3[0])
self.assertAlmostEqual(spectrum[0], tapered_spectrum_2_1[0])
self.assertTrue(
numpy.allclose(tapered_spectrum_0_3, tapered_spectrum_2_1))
def test_tappering_stabilizer_more_qubits(self):
"""Test for stabilizer with more qubits than operator."""
hamiltonian = QubitOperator('Y0 Y1', 1.0)
stab = QubitOperator('X0 X1 X2', -1.0)
num_qubits = max(count_qubits(hamiltonian), count_qubits(stab))
tap_ham = taper_off_qubits(hamiltonian, stab)
num_qubits_tap = count_qubits(tap_ham)
self.assertFalse(num_qubits == num_qubits_tap)
hamiltonian = QubitOperator('X0 X1', 1.0)
stab = QubitOperator('Y0 Y1 Y2', -1.0)
num_qubits = max(count_qubits(hamiltonian), count_qubits(stab))
tap_ham = taper_off_qubits(hamiltonian, stab)
num_qubits_tap = count_qubits(tap_ham)
self.assertFalse(num_qubits == num_qubits_tap)
def test_tapering_qubits_manual_input_false(self):
"""Test taper_off_qubits function using LiH Hamiltonian."""
hamiltonian, spectrum = lih_hamiltonian()
qubit_hamiltonian = jordan_wigner(hamiltonian)
stab1 = QubitOperator('Z0 Z2', -1.0)
stab2 = QubitOperator('Z1 Z3', -1.0)
tapered_hamiltonian = taper_off_qubits(operator=qubit_hamiltonian,
stabilizers=[stab1, stab2],
manual_input=False,
fixed_positions=[0, 3])
tapered_spectrum = eigenspectrum(tapered_hamiltonian)
self.assertAlmostEqual(spectrum[0], tapered_spectrum[0])