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Added missing label support for some QuantumCircuit gate-applying methods #14980

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a7ad937
Fix: added label attribute to some gate methods in quantumcircuit.py
Bruno-Danti Sep 2, 2025
5fbc04b
Added a unit test
Bruno-Danti Sep 2, 2025
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55 changes: 38 additions & 17 deletions qiskit/circuit/quantumcircuit.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5305,7 +5305,8 @@ def mcrz(
self.compose(cgate, control_qubits + [target_qubit], inplace=True)

def r(
self, theta: ParameterValueType, phi: ParameterValueType, qubit: QubitSpecifier
self, theta: ParameterValueType, phi: ParameterValueType, qubit: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RGate`.

Expand All @@ -5315,11 +5316,12 @@ def r(
theta: The angle of the rotation.
phi: The angle of the axis of rotation in the x-y plane.
qubit: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.R, [qubit], [theta, phi])
return self._append_standard_gate(StandardGate.R, [qubit], [theta, phi], label = label)

def rv(
self,
Expand Down Expand Up @@ -5353,6 +5355,7 @@ def rccx(
control_qubit1: QubitSpecifier,
control_qubit2: QubitSpecifier,
target_qubit: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RCCXGate`.

Expand All @@ -5362,12 +5365,13 @@ def rccx(
control_qubit1: The qubit(s) used as the first control.
control_qubit2: The qubit(s) used as the second control.
target_qubit: The qubit(s) targeted by the gate.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(
StandardGate.RCCX, [control_qubit1, control_qubit2, target_qubit], ()
StandardGate.RCCX, [control_qubit1, control_qubit2, target_qubit], (), label = label
)

def rcccx(
Expand All @@ -5376,6 +5380,7 @@ def rcccx(
control_qubit2: QubitSpecifier,
control_qubit3: QubitSpecifier,
target_qubit: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RC3XGate`.

Expand All @@ -5386,6 +5391,7 @@ def rcccx(
control_qubit2: The qubit(s) used as the second control.
control_qubit3: The qubit(s) used as the third control.
target_qubit: The qubit(s) targeted by the gate.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
Expand All @@ -5394,6 +5400,7 @@ def rcccx(
StandardGate.RC3X,
[control_qubit1, control_qubit2, control_qubit3, target_qubit],
(),
label = label
)

def rx(
Expand Down Expand Up @@ -5453,7 +5460,8 @@ def crx(
)

def rxx(
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RXXGate`.

Expand All @@ -5463,11 +5471,12 @@ def rxx(
theta: The angle of the rotation.
qubit1: The qubit(s) to apply the gate to.
qubit2: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.RXX, [qubit1, qubit2], [theta])
return self._append_standard_gate(StandardGate.RXX, [qubit1, qubit2], [theta], label = label)

def ry(
self, theta: ParameterValueType, qubit: QubitSpecifier, label: str | None = None
Expand Down Expand Up @@ -5526,7 +5535,8 @@ def cry(
)

def ryy(
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RYYGate`.

Expand All @@ -5536,25 +5546,28 @@ def ryy(
theta: The rotation angle of the gate.
qubit1: The qubit(s) to apply the gate to.
qubit2: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.RYY, [qubit1, qubit2], [theta])
return self._append_standard_gate(StandardGate.RYY, [qubit1, qubit2], [theta], label = label)

def rz(self, phi: ParameterValueType, qubit: QubitSpecifier) -> InstructionSet:
def rz(self, phi: ParameterValueType, qubit: QubitSpecifier,
label: str | None = None) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RZGate`.

For the full matrix form of this gate, see the underlying gate documentation.

Args:
phi: The rotation angle of the gate.
qubit: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.RZ, [qubit], [phi])
return self._append_standard_gate(StandardGate.RZ, [qubit], [phi], label = label)

def crz(
self,
Expand Down Expand Up @@ -5596,7 +5609,8 @@ def crz(
)

def rzx(
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RZXGate`.

Expand All @@ -5606,14 +5620,17 @@ def rzx(
theta: The rotation angle of the gate.
qubit1: The qubit(s) to apply the gate to.
qubit2: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.


Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.RZX, [qubit1, qubit2], [theta])
return self._append_standard_gate(StandardGate.RZX, [qubit1, qubit2], [theta], label = label)

def rzz(
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier
self, theta: ParameterValueType, qubit1: QubitSpecifier, qubit2: QubitSpecifier,
label: str | None = None
) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.RZZGate`.

Expand All @@ -5623,37 +5640,41 @@ def rzz(
theta: The rotation angle of the gate.
qubit1: The qubit(s) to apply the gate to.
qubit2: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.RZZ, [qubit1, qubit2], [theta])
return self._append_standard_gate(StandardGate.RZZ, [qubit1, qubit2], [theta], label = label)

def ecr(self, qubit1: QubitSpecifier, qubit2: QubitSpecifier) -> InstructionSet:
def ecr(self, qubit1: QubitSpecifier, qubit2: QubitSpecifier,
label: str | None = None) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.ECRGate`.

For the full matrix form of this gate, see the underlying gate documentation.

Args:
qubit1, qubit2: The qubits to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.ECR, [qubit1, qubit2], ())
return self._append_standard_gate(StandardGate.ECR, [qubit1, qubit2], (), label = label)

def s(self, qubit: QubitSpecifier) -> InstructionSet:
def s(self, qubit: QubitSpecifier, label: str | None = None) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.SGate`.

For the full matrix form of this gate, see the underlying gate documentation.

Args:
qubit: The qubit(s) to apply the gate to.
label: The string label of the gate in the circuit.

Returns:
A handle to the instructions created.
"""
return self._append_standard_gate(StandardGate.S, [qubit], ())
return self._append_standard_gate(StandardGate.S, [qubit], (), label = label)

def sdg(self, qubit: QubitSpecifier) -> InstructionSet:
"""Apply :class:`~qiskit.circuit.library.SdgGate`.
Expand Down
17 changes: 17 additions & 0 deletions test/python/circuit/test_gate_labels.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
from test import QiskitTestCase
import numpy as np
from qiskit import QuantumCircuit


class TestGateLabels(QiskitTestCase):
def test_gate_labels_are_applied(self):
Comment on lines +6 to +7
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Could we put this test function in an existing class in test/python/circuit/test_circuit_operations.py, just to avoid an extra stub file? There's no perfect place for it, but I think we can avoid the new file.

qc = QuantumCircuit(2)
# Make gates with labels
qc.rz(np.pi, 0, label="rz_gate")
qc.rxx(np.pi, 0, 1, "rxx_gate")
qc.s(0, "s_gate")

# Check labels are there
assert qc.data[0].label == "rz_gate"
assert qc.data[1].label == "rxx_gate"
assert qc.data[2].label == "s_gate"
Comment on lines +14 to +17
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Qiskit uses the built-in unittest runner, so these should be self.assertEqual(qc.data[0].label, "rz_gate") to handle assertion failures / messages better.