Quellcode für qiskit.converters.circuit_to_gate

# This code is part of Qiskit.
# (C) Copyright IBM 2017, 2019.
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""Helper function for converting a circuit to a gate"""
from qiskit.circuit.gate import Gate
from qiskit.circuit.quantumregister import QuantumRegister
from qiskit.exceptions import QiskitError

[Doku]def circuit_to_gate(circuit, parameter_map=None, equivalence_library=None, label=None): """Build a :class:`.Gate` object from a :class:`.QuantumCircuit`. The gate is anonymous (not tied to a named quantum register), and so can be inserted into another circuit. The gate will have the same string name as the circuit. Args: circuit (QuantumCircuit): the input circuit. parameter_map (dict): For parameterized circuits, a mapping from parameters in the circuit to parameters to be used in the gate. If None, existing circuit parameters will also parameterize the Gate. equivalence_library (EquivalenceLibrary): Optional equivalence library where the converted gate will be registered. label (str): Optional gate label. Raises: QiskitError: if circuit is non-unitary or if parameter_map is not compatible with circuit Return: Gate: a Gate equivalent to the action of the input circuit. Upon decomposition, this gate will yield the components comprising the original circuit. """ # pylint: disable=cyclic-import from qiskit.circuit.quantumcircuit import QuantumCircuit if circuit.clbits: raise QiskitError("Circuit with classical bits cannot be converted to gate.") for instruction in circuit.data: if not isinstance(instruction.operation, Gate): raise QiskitError( ( "One or more instructions cannot be converted to" ' a gate. "{}" is not a gate instruction' ).format(instruction.operation.name) ) if parameter_map is None: parameter_dict = {p: p for p in circuit.parameters} else: parameter_dict = circuit._unroll_param_dict(parameter_map) if parameter_dict.keys() != circuit.parameters: raise QiskitError( ( "parameter_map should map all circuit parameters. " "Circuit parameters: {}, parameter_map: {}" ).format(circuit.parameters, parameter_dict) ) gate = Gate( name=circuit.name, num_qubits=circuit.num_qubits, params=[*parameter_dict.values()], label=label, ) gate.condition = None target = circuit.assign_parameters(parameter_dict, inplace=False) if equivalence_library is not None: equivalence_library.add_equivalence(gate, target) qc = QuantumCircuit(name=gate.name, global_phase=target.global_phase) if gate.num_qubits > 0: q = QuantumRegister(gate.num_qubits, "q") qc.add_register(q) qubit_map = {bit: q[idx] for idx, bit in enumerate(circuit.qubits)} # The 3rd parameter in the output tuple) is hard coded to [] because # Gate objects do not have cregs set and we've verified that all # instructions are gates for instruction in target.data: qc._append(instruction.replace(qubits=tuple(qubit_map[y] for y in instruction.qubits))) gate.definition = qc return gate