def state_vector_has_stabilizer(state_vector: np.ndarray, stabilizer: DensePauliString) -> bool: """Checks that the state_vector is stabilized by the given stabilizer. The stabilizer should not modify the value of the state_vector, up to the global phase. Args: state_vector: An input state vector. Is not mutated by this function. stabilizer: A potential stabilizer of the above state_vector as a DensePauliString. Returns: Whether the stabilizer stabilizes the supplied state. """ qubits = LineQubit.range(protocols.num_qubits(stabilizer)) args = act_on_state_vector_args.ActOnStateVectorArgs( target_tensor=state_vector.copy(), available_buffer=np.empty_like(state_vector), qubits=qubits, prng=np.random.RandomState(), log_of_measurement_results={}, ) protocols.act_on(stabilizer, args, qubits) return np.allclose(args.target_tensor, state_vector)
def assert_act_on_clifford_tableau_effect_matches_unitary(val: Any) -> None: """Checks that act_on with CliffordTableau generates stabilizers that stabilize the final state vector. Does not work with Operations or Gates expecting non-qubit Qids.""" # pylint: disable=unused-variable __tracebackhide__ = True # pylint: enable=unused-variable num_qubits_val = protocols.num_qubits(val) if not protocols.has_unitary(val) or \ protocols.qid_shape(val) != (2,) * num_qubits_val: return None qubits = LineQubit.range(protocols.num_qubits(val) * 2) qubit_map = {qubit: i for i, qubit in enumerate(qubits)} circuit = Circuit() for i in range(num_qubits_val): circuit.append([ common_gates.H(qubits[i]), common_gates.CNOT(qubits[i], qubits[-i - 1]) ]) if hasattr(val, "on"): circuit.append(val.on(*qubits[:num_qubits_val])) else: circuit.append(val.with_qubits(*qubits[:num_qubits_val])) tableau = _final_clifford_tableau(circuit, qubit_map) if tableau is None: return None state_vector = np.reshape(final_state_vector(circuit, qubit_order=qubits), protocols.qid_shape(qubits)) assert all( state_vector_has_stabilizer(state_vector, stab) for stab in tableau.stabilizers()), ( "act_on clifford tableau is not consistent with " "final_state_vector simulation.\n\nval: {!r}".format(val))
def assert_all_implemented_act_on_effects_match_unitary( val: Any, assert_tableau_implemented: bool = False, assert_ch_form_implemented: bool = False) -> None: """Uses val's effect on final_state_vector to check act_on(val)'s behavior. Checks that act_on with CliffordTableau or StabilizerStateCHForm behaves consistently with act_on through final state vector. Does not work with Operations or Gates expecting non-qubit Qids. If either of the assert_*_implmented args is true, fails if the corresponding method is not implemented for the test circuit. Args: val: A gate or operation that may be an input to protocols.act_on. assert_tableau_implemented: asserts that protocols.act_on() works with val and ActOnCliffordTableauArgs inputs. assert_ch_form_implemented: asserts that protocols.act_on() works with val and ActOnStabilizerStateChFormArgs inputs. """ # pylint: disable=unused-variable __tracebackhide__ = True # pylint: enable=unused-variable num_qubits_val = protocols.num_qubits(val) if (protocols.is_parameterized(val) or not protocols.has_unitary(val) or protocols.qid_shape(val) != (2, ) * num_qubits_val): if assert_tableau_implemented or assert_ch_form_implemented: assert False, ("Could not assert if any act_on methods were " "implemented. Operating on qudits or with a " "non-unitary or parameterized operation is " "unsupported.\n\nval: {!r}".format(val)) return None qubits = LineQubit.range(protocols.num_qubits(val) * 2) qubit_map = {qubit: i for i, qubit in enumerate(qubits)} circuit = Circuit() for i in range(num_qubits_val): circuit.append([ common_gates.H(qubits[i]), common_gates.CNOT(qubits[i], qubits[-i - 1]) ]) if hasattr(val, "on"): circuit.append(val.on(*qubits[:num_qubits_val])) else: circuit.append(val.with_qubits(*qubits[:num_qubits_val])) state_vector = np.reshape(final_state_vector(circuit, qubit_order=qubits), protocols.qid_shape(qubits)) tableau = _final_clifford_tableau(circuit, qubit_map) if tableau is None: assert ( not assert_tableau_implemented ), "Failed to generate final tableau for the test circuit.\n\nval: {!r}".format( val) else: assert all( state_vector_has_stabilizer(state_vector, stab) for stab in tableau.stabilizers()), ( "act_on clifford tableau is not consistent with " "final_state_vector simulation.\n\nval: {!r}".format(val)) stabilizer_ch_form = _final_stabilizer_state_ch_form(circuit, qubit_map) if stabilizer_ch_form is None: assert not assert_ch_form_implemented, ("Failed to generate final " "stabilizer state CH form " "for the test circuit." "\n\nval: {!r}".format(val)) else: np.testing.assert_allclose( np.reshape(stabilizer_ch_form.state_vector(), protocols.qid_shape(qubits)), state_vector, atol=1e-07, err_msg= f"stabilizer_ch_form.state_vector disagrees with state_vector for {val!r}", verbose=True, )