Pauli X, Y, Z measurement instructions

qiskit/circuit/__init__.py

@@ -286,7 +286,7 @@
 from .operation import Operation
 from .barrier import Barrier
 from .delay import Delay
-from .measure import Measure
+from .measure import Measure, MeasureX, MeasureY, MeasureZ
 from .reset import Reset
 from .parameter import Parameter
 from .parametervector import ParameterVector

qiskit/circuit/library/__init__.py

@@ -136,6 +136,9 @@
    :toctree: ../stubs/
 
    Measure
+   MeasureX
+   MeasureY
+   MeasureZ
    Reset
 
 Generalized Gates
@@ -471,7 +474,7 @@
 from .standard_gates import *
 from .templates import *
 from ..barrier import Barrier
-from ..measure import Measure
+from ..measure import Measure, MeasureX, MeasureY, MeasureZ
 from ..reset import Reset
 
 

qiskit/circuit/library/standard_gates/__init__.py

@@ -109,7 +109,7 @@ def get_standard_gate_name_mapping():
     """Return a dictionary mapping the name of standard gates and instructions to an object for
     that name."""
     from qiskit.circuit.parameter import Parameter
-    from qiskit.circuit.measure import Measure
+    from qiskit.circuit.measure import Measure, MeasureX, MeasureY, MeasureZ
     from qiskit.circuit.delay import Delay
     from qiskit.circuit.reset import Reset
 
@@ -169,6 +169,9 @@ def get_standard_gate_name_mapping():
         ZGate(),
         Delay(Parameter("t")),
         Measure(),
+        MeasureX(),
+        MeasureY(),
+        MeasureZ(),
     ]
     name_mapping = {gate.name: gate for gate in gates}
     return name_mapping

qiskit/circuit/measure.py

@@ -14,15 +14,21 @@
 Quantum measurement in the computational basis.
 """
 
+from __future__ import annotations
+
 import warnings
 
 from qiskit.circuit.instruction import Instruction
 from qiskit.circuit.exceptions import CircuitError
 
 
+# Measure class kept for backwards compatibility, and repurposed
+# as a common parent class for all measurement instructions.
 class Measure(Instruction):
     """Quantum measurement in the computational basis."""
 
+    basis: str | None = None
+
     def __init__(self):
         """Create new measurement instruction."""
         super().__init__("measure", 1, 1, [])
@@ -41,6 +47,70 @@ def broadcast_arguments(self, qargs, cargs):
             raise CircuitError("register size error")
 
 
+class MeasureX(Measure):
+    """Quantum measurement in the X basis."""
+
+    basis: str | None = "X"
+
+    def __init__(self):
+        """Create new X measurement instruction."""
+        # pylint: disable=bad-super-call
+        super(Measure, self).__init__("measure_x", 1, 1, [])
+
+    def _define(self):
+        # pylint: disable=cyclic-import
+        from qiskit.circuit.quantumcircuit import QuantumCircuit
+
+        qc = QuantumCircuit(1, 1)
+        qc.h(0)
+        qc.measure_z(0, 0)
+        qc.h(0)
+
+        self.definition = qc
+
+
+class MeasureY(Measure):
+    """Quantum measurement in the Y basis."""
+
+    basis: str | None = "Y"
+
+    def __init__(self):
+        """Create new Y measurement instruction."""
+        # pylint: disable=bad-super-call
+        super(Measure, self).__init__("measure_y", 1, 1, [])
+
+    def _define(self):
+        # pylint: disable=cyclic-import
+        from qiskit.circuit.quantumcircuit import QuantumCircuit
+
+        qc = QuantumCircuit(1, 1)
+        qc.sdg(0)
+        qc.measure_x(0, 0)
+        qc.s(0)
+
+        self.definition = qc
+
+
+class MeasureZ(Measure):
+    """Quantum Z measurement in the Z basis."""
+
+    basis: str | None = "Z"
+
+    def __init__(self):
+        """Create new measurement instruction."""
+        # pylint: disable=bad-super-call
+        super(Measure, self).__init__("measure_z", 1, 1, [])
+
+    def _define(self):
+        # pylint: disable=cyclic-import
+        from qiskit.circuit.quantumcircuit import QuantumCircuit
+
+        qc = QuantumCircuit(1, 1)
+        qc.measure(0, 0)
+
+        self.definition = qc
+
+
 def measure(circuit, qubit, clbit):
     """Measure a quantum bit into classical bit.
 

qiskit/circuit/quantumcircuit.py

@@ -57,7 +57,7 @@
 from .bit import Bit
 from .quantumcircuitdata import QuantumCircuitData, CircuitInstruction
 from .delay import Delay
-from .measure import Measure
+from .measure import Measure, MeasureX, MeasureY, MeasureZ
 from .reset import Reset
 
 try:
@@ -2259,6 +2259,51 @@ def measure(self, qubit: QubitSpecifier, cbit: ClbitSpecifier) -> InstructionSet
         """
         return self.append(Measure(), [qubit], [cbit])
 
+    def measure_x(self, qubit: QubitSpecifier, cbit: ClbitSpecifier) -> InstructionSet:
+        """Measure quantum bit into classical bit (tuples), in the X basis.
+
+        Args:
+            qubit: qubit to measure.
+            cbit: classical bit to place the measurement in.
+
+        Returns:
+            qiskit.circuit.InstructionSet: handle to the added instructions.
+
+        Raises:
+            CircuitError: if arguments have bad format.
+        """
+        return self.append(MeasureX(), [qubit], [cbit])
+
+    def measure_y(self, qubit: QubitSpecifier, cbit: ClbitSpecifier) -> InstructionSet:
+        """Measure quantum bit into classical bit (tuples), in the Y basis.
+
+        Args:
+            qubit: qubit to measure.
+            cbit: classical bit to place the measurement in.
+
+        Returns:
+            qiskit.circuit.InstructionSet: handle to the added instructions.
+
+        Raises:
+            CircuitError: if arguments have bad format.
+        """
+        return self.append(MeasureY(), [qubit], [cbit])
+
+    def measure_z(self, qubit: QubitSpecifier, cbit: ClbitSpecifier) -> InstructionSet:
+        """Measure quantum bit into classical bit (tuples), in the Z basis.
+
+        Args:
+            qubit: qubit to measure.
+            cbit: classical bit to place the measurement in.
+
+        Returns:
+            qiskit.circuit.InstructionSet: handle to the added instructions.
+
+        Raises:
+            CircuitError: if arguments have bad format.
+        """
+        return self.append(MeasureZ(), [qubit], [cbit])
+
     def measure_active(self, inplace: bool = True) -> Optional["QuantumCircuit"]:
         """Adds measurement to all non-idle qubits. Creates a new ClassicalRegister with
         a size equal to the number of non-idle qubits being measured.

qiskit/dagcircuit/dagdependency.py

@@ -21,9 +21,10 @@
 
 from qiskit.circuit.quantumregister import QuantumRegister, Qubit
 from qiskit.circuit.classicalregister import ClassicalRegister, Clbit
+from qiskit.circuit.commutation_checker import CommutationChecker
+from qiskit.circuit.measure import Measure
 from qiskit.dagcircuit.exceptions import DAGDependencyError
 from qiskit.dagcircuit.dagdepnode import DAGDepNode
-from qiskit.circuit.commutation_checker import CommutationChecker
 
 
 # ToDo: DagDependency needs to be refactored:
@@ -382,8 +383,12 @@ def _create_op_node(self, operation, qargs, cargs):
         Returns:
             DAGDepNode: the newly added node.
         """
-        directives = ["measure"]
-        if not getattr(operation, "_directive", False) and operation.name not in directives:
+        directives = []
+        if (
+            not getattr(operation, "_directive", False)
+            and not isinstance(operation, Measure)
+            and operation.name not in directives
+        ):
             qindices_list = []
             for elem in qargs:
                 qindices_list.append(self.qubits.index(elem))

qiskit/visualization/circuit/latex.py

@@ -189,7 +189,7 @@ def __init__(
         # If there is any custom instruction that uses classical bits
         # then cregbundle is forced to be False.
         for node in itertools.chain.from_iterable(self._nodes):
-            if node.cargs and node.op.name != "measure":
+            if node.cargs and not isinstance(node.op, Measure):
                 if cregbundle:
                     warn(
                         "Cregbundle set to False since an instruction needs to refer"
@@ -300,7 +300,7 @@ def _get_image_depth(self):
             self._nodes
             and self._nodes[0]
             and (
-                self._nodes[0][0].op.name == "measure"
+                isinstance(self._nodes[0][0].op, Measure)
                 or getattr(self._nodes[0][0].op, "condition", None)
             )
         ):
@@ -427,7 +427,7 @@ def _build_latex_array(self):
             self._nodes
             and self._nodes[0]
             and (
-                self._nodes[0][0].op.name == "measure"
+                isinstance(self._nodes[0][0].op, Measure)
                 or getattr(self._nodes[0][0].op, "condition", None)
             )
         ):
@@ -579,7 +579,26 @@ def _build_symmetric_gate(self, op, gate_text, wire_list, col):
     def _build_measure(self, node, col):
         """Build a meter and the lines to the creg"""
         wire1 = self._wire_map[node.qargs[0]]
-        self._latex[wire1][col] = "\\meter"
+        if node.op.basis:
+            # Modification of `\meter` in https://www.ctan.org/tex-archive/graphics/qcircuit
+            # pylint: disable=invalid-name
+            PAULI_METER = """
+                *=<1.8em,1.4em>
+                {
+                    \\xy ="j",
+                    "j"-<.778em,.322em>;{"j"+<.778em,-.322em> \\ellipse ur,_{}},
+                    "j"-<0em,.4em>;p+<.5em,.9em> **\\dir{-},
+                    "j"+<2.2em,2.2em>*{},"j"-<2.2em,2.2em>*{},
+                    <-.5em,.4em> *\\txt{\\tiny{%s}}
+                    \\endxy
+                } 
+                \\POS ="i",
+                "i"+UR;"i"+UL **\\dir{-};"i"+DL **\\dir{-};"i"+DR **\\dir{-};"i"+UR **\\dir{-},
+                "i" \\qw
+            """
+            self._latex[wire1][col] = PAULI_METER % node.op.basis.upper()
+        else:
+            self._latex[wire1][col] = "\\meter"
 
         idx_str = ""
         cond_offset = 1.5 if getattr(node.op, "condition", None) else 0.0

qiskit/visualization/circuit/matplotlib.py

@@ -199,7 +199,7 @@ def __init__(
         self._calibrations = self._circuit.calibrations
 
         for node in itertools.chain.from_iterable(self._nodes):
-            if node.cargs and node.op.name != "measure":
+            if node.cargs and not isinstance(node.op, Measure):
                 if cregbundle:
                     warn(
                         "Cregbundle set to False since an instruction needs to refer"
@@ -992,6 +992,17 @@ def _measure(self, node):
             linewidth=self._lwidth2,
             zorder=PORDER_GATE,
         )
+        if node.op.basis:
+            self._ax.text(
+                qx - 0.4 * WID,
+                qy + 0.25 * HIG,
+                node.op.basis.upper(),
+                color=self._data[node]["gt"],
+                clip_on=True,
+                zorder=PORDER_TEXT,
+                fontsize=0.5 * self._style["fs"],
+                fontweight="bold",
+            )
         # arrow
         self._line(
             self._data[node]["q_xy"][0],

qiskit/visualization/circuit/qcstyle.py

@@ -160,6 +160,9 @@ class DefaultStyle:
                 'reset': ('#000000', '#FFFFFF'),
                 'target': ('#FFFFFF', '#FFFFFF'),
                 'measure': ('#000000', '#FFFFFF'),
+                'measure_x': ('#000000', '#FFFFFF'),
+                'measure_y': ('#000000', '#FFFFFF'),
+                'measure_z': ('#000000', '#FFFFFF'),
             }
 
     """
@@ -261,6 +264,9 @@ def __init__(self):
                 "reset": (colors["black"], colors["white"]),
                 "target": (colors["white"], colors["white"]),
                 "measure": (colors["black"], colors["white"]),
+                "measure_x": (colors["black"], colors["white"]),
+                "measure_y": (colors["black"], colors["white"]),
+                "measure_z": (colors["black"], colors["white"]),
             },
         }
 

qiskit/visualization/circuit/styles/bw.json

@@ -197,6 +197,18 @@
         "measure": [
             "#000000",
             "#FFFFFF"
+        ],
+        "measure_x": [
+            "#000000",
+            "#FFFFFF"
+        ],
+        "measure_y": [
+            "#000000",
+            "#FFFFFF"
+        ],
+        "measure_z": [
+            "#000000",
+            "#FFFFFF"
         ]
     }
 }

qiskit/visualization/circuit/styles/default.json

@@ -197,6 +197,18 @@
         "measure": [
             "#000000",
             "#FFFFFF"
+        ],
+        "measure_x": [
+            "#000000",
+            "#FFFFFF"
+        ],
+        "measure_y": [
+            "#000000",
+            "#FFFFFF"
+        ],
+        "measure_z": [
+            "#000000",
+            "#FFFFFF"
         ]
     }
 }

qiskit/visualization/circuit/styles/iqx-dark.json

@@ -197,6 +197,18 @@
         "measure": [
             "#8D8D8D",
             "#000000"
+        ],
+        "measure_x": [
+            "#8D8D8D",
+            "#000000"
+        ],
+        "measure_y": [
+            "#8D8D8D",
+            "#000000"
+        ],
+        "measure_z": [
+            "#8D8D8D",
+            "#000000"
         ]
     }
 }