diff --git a/qiskit/quantum_info/operators/symplectic/pauli_utils.py b/qiskit/quantum_info/operators/symplectic/pauli_utils.py index e4a3552b5076..0d2529fcb7fe 100644 --- a/qiskit/quantum_info/operators/symplectic/pauli_utils.py +++ b/qiskit/quantum_info/operators/symplectic/pauli_utils.py @@ -13,20 +13,30 @@ PauliList utility functions. """ +import warnings from qiskit.quantum_info.operators.symplectic.pauli_list import PauliList -def pauli_basis(num_qubits, weight=False): +def pauli_basis(num_qubits, weight=False, pauli_list=None): """Return the ordered PauliTable or PauliList for the n-qubit Pauli basis. Args: num_qubits (int): number of qubits weight (bool): if True optionally return the basis sorted by Pauli weight rather than lexicographic order (Default: False) + pauli_list (bool): [Deprecated] This argument is deprecated and remains + for backwards compatability. It has no effect. Returns: - PauliTable, PauliList: the Paulis for the basis + PauliList: the Paulis for the basis """ + if pauli_list is not None: + warnings.warn( + "The `pauli_list` kwarg is deprecated as of Qiskit Terra 0.22 and " + "no longer has an effect as `pauli_basis` always returns a PauliList.", + DeprecationWarning, + stacklevel=2, + ) pauli_1q = PauliList(["I", "X", "Y", "Z"]) if num_qubits == 1: return pauli_1q diff --git a/releasenotes/notes/fix-pauli-basis-dep-27c0a4506ad38d2c.yaml b/releasenotes/notes/fix-pauli-basis-dep-27c0a4506ad38d2c.yaml new file mode 100644 index 000000000000..5ae9579ee69f --- /dev/null +++ b/releasenotes/notes/fix-pauli-basis-dep-27c0a4506ad38d2c.yaml @@ -0,0 +1,11 @@ +--- +deprecations: + - | + The ``pauli_list`` kwarg of :func:`.pauli_basis` has been deprecated as + :func:`.pauli_basis` now always returns a :class:`.PauliList`. +fixes: + - | + Fixes the removal of ``pauli_list`` kwarg of :func:`.pauli_basis` which + broke existing code using the ``pauli_list=True`` future compatibility on + upgrade to Qiskit Terra 0.22. This kwarg has been added back to the the + function with a deprecation warning instead.