qiskit_addon_cutting.utils.transforms.separate_circuit

separate_circuit(circuit, partition_labels=None)[source]

Separate the circuit into its disconnected components.

If partition_labels is provided, then the circuit will be separated according to those labels. A partition label of None is treated specially: it must be applied to an unused (idle) qubit, and that qubit will be removed when separating the circuit.

If partition_labels is None, then the circuit will be fully separated into its disconnected components, each of which will be labeled with consecutive integers starting with 0. Each idle wire will be eliminated in the resulting circuits.

>>> qc = QuantumCircuit(4)
>>> _ = qc.x(0)
>>> _ = qc.cx(1, 2)
>>> separate_circuit(qc, "ABBA").subcircuits.keys()
dict_keys(['A', 'B'])
>>> separate_circuit(qc, "ABBA").qubit_map
[('A', 0), ('B', 0), ('B', 1), ('A', 1)]
>>> separate_circuit(qc, ["A", "B", "B", None]).qubit_map
[('A', 0), ('B', 0), ('B', 1), (None, None)]
>>> separate_circuit(qc).subcircuits.keys()
dict_keys([0, 1])
>>> separate_circuit(qc).qubit_map
[(0, 0), (1, 0), (1, 1), (None, None)]
>>> separate_circuit(qc, "BAAC").subcircuits.keys()
dict_keys(['B', 'A', 'C'])
>>> separate_circuit(qc, "BAAC").qubit_map
[('B', 0), ('A', 0), ('A', 1), ('C', 0)]
Parameters:

  • circuit (QuantumCircuit) – The circuit to separate into disconnected subcircuits

  • partition_labels (Sequence[Hashable] | None) – A sequence of length num_qubits. Qubits with the same label will end up in the same subcircuit.

Return type:

SeparatedCircuits

Returns:

A SeparatedCircuits named tuple containing the subcircuits and qubit_map.

Raises:

  • ValueError – The number of partition labels does not equal the number of qubits in the input circuit.

  • ValueError – Operation spans more than one partition.