def phase_estimation(
self,
unitary_circuit,
state_preparation=None,
num_evaluation_qubits=6,
backend=None,
construct_circuit=False,
):
"""Run phase estimation with operator, eigenvalue pair `unitary_circuit`,
`state_preparation`. Return all results
"""
if backend is None:
backend = qiskit.BasicAer.get_backend("statevector_simulator")
qi = qiskit.utils.QuantumInstance(backend=backend, shots=10000)
phase_est = PhaseEstimation(
num_evaluation_qubits=num_evaluation_qubits, quantum_instance=qi)
if construct_circuit:
pe_circuit = phase_est.construct_circuit(unitary_circuit,
state_preparation)
result = phase_est.estimate_from_pe_circuit(
pe_circuit, unitary_circuit.num_qubits)
else:
result = phase_est.estimate(unitary=unitary_circuit,
state_preparation=state_preparation)
return result
def one_phase(
self,
unitary_circuit,
state_preparation=None,
backend_type=None,
phase_estimator=None,
num_iterations=6,
):
"""Run phase estimation with operator, eigenvalue pair `unitary_circuit`,
`state_preparation`. Return the estimated phase as a value in :math:`[0,1)`.
"""
if backend_type is None:
backend_type = "qasm_simulator"
backend = qiskit.BasicAer.get_backend(backend_type)
qi = qiskit.utils.QuantumInstance(backend=backend, shots=10000)
if phase_estimator is None:
phase_estimator = IterativePhaseEstimation
if phase_estimator == IterativePhaseEstimation:
p_est = IterativePhaseEstimation(num_iterations=num_iterations,
quantum_instance=qi)
elif phase_estimator == PhaseEstimation:
p_est = PhaseEstimation(num_evaluation_qubits=6,
quantum_instance=qi)
else:
raise ValueError("Unrecognized phase_estimator")
result = p_est.estimate(unitary=unitary_circuit,
state_preparation=state_preparation)
phase = result.phase
return phase
def one_phase(self,
unitary_circuit,
state_preparation=None,
n_eval_qubits=6,
backend=None):
"""Run phase estimation with operator, eigenvalue pair `unitary_circuit`,
`state_preparation`. Return the bit string with the largest amplitude.
"""
if backend is None:
backend = qiskit.BasicAer.get_backend('qasm_simulator')
qi = qiskit.utils.QuantumInstance(backend=backend, shots=10000)
p_est = PhaseEstimation(num_evaluation_qubits=n_eval_qubits,
quantum_instance=qi)
result = p_est.estimate(unitary=unitary_circuit,
state_preparation=state_preparation)
phase = result.most_likely_phase
return phase