Add support for cut ECRGate

circuit_knitting/cutting/qpd/qpd.py

@@ -34,6 +34,7 @@
     SGate,
     TGate,
     SdgGate,
+    SXGate,
     RXGate,
     RYGate,
     RZGate,
@@ -47,6 +48,7 @@
     CRXGate,
     CRYGate,
     CRZGate,
+    ECRGate,
     CSXGate,
 )
 
@@ -195,7 +197,7 @@ def qpdbasis_from_gate(gate: Gate) -> QPDBasis:
     """
     Generate a QPDBasis object, given a supported operation.
 
-    This method currently supports 10 operations:
+    This method currently supports the following operations:
         - :class:`~qiskit.circuit.library.RXXGate`
         - :class:`~qiskit.circuit.library.RYYGate`
         - :class:`~qiskit.circuit.library.RZZGate`
@@ -207,6 +209,9 @@ def qpdbasis_from_gate(gate: Gate) -> QPDBasis:
         - :class:`~qiskit.circuit.library.CZGate`
         - :class:`~qiskit.circuit.library.CHGate`
 
+    The above gate names can also be determined by calling
+    :func:`supported_gates`.
+
     Returns:
         The newly-instantiated :class:`QPDBasis` object
 
@@ -339,7 +344,7 @@ def _(gate: CXGate | CYGate | CZGate | CHGate):
 
     if gate.name != "cz":
         # Modify `maps` to sandwich the target operations inside of basis rotations
-        for operations in {id(m[1]): m[1] for m in maps}.values():
+        for operations in unique_by_id(m[1] for m in maps):
             if operations:
                 if gate.name in ("cx", "cy"):
                     operations.insert(0, HGate())
@@ -356,6 +361,19 @@ def _(gate: CXGate | CYGate | CZGate | CHGate):
     return QPDBasis(maps, coeffs)
 
 
+@_register_qpdbasis_from_gate("ecr")
+def _(gate: ECRGate):
+    retval = qpdbasis_from_gate(CXGate())
+    # Modify basis according to ECRGate definition in Qiskit circuit library
+    # https://github.com/Qiskit/qiskit-terra/blob/d9763523d45a747fd882a7e79cc44c02b5058916/qiskit/circuit/library/standard_gates/equivalence_library.py#L656-L663
+    for operations in unique_by_id(m[0] for m in retval.maps):
+        operations.insert(0, SGate())
+        operations.append(XGate())
+    for operations in unique_by_id(m[1] for m in retval.maps):
+        operations.insert(0, SXGate())
+    return retval
+
+
 def _validate_qpd_instructions(
     circuit: QuantumCircuit, instruction_ids: Sequence[Sequence[int]]
 ):

releasenotes/notes/additional-gates-f4ed6c0e8dc3a9be.yaml

@@ -4,3 +4,5 @@ features:
     This release adds support for additional cut gates:
     - :class:`~qiskit.circuit.library.CHGate`
     - :class:`~qiskit.circuit.library.CYGate`
+    - :class:`~qiskit.circuit.library.SXGate`
+    - :class:`~qiskit.circuit.library.ECRGate`

test/cutting/qpd/test_qpd.py

@@ -238,7 +238,10 @@ def test_decompose_qpd_instructions(self):
     # Optimal values from https://arxiv.org/abs/2205.00016v2 Corollary 4.4 (page 10)
     @data(
         (CXGate(), 3),
+        (CYGate(), 3),
         (CZGate(), 3),
+        (CHGate(), 3),
+        (ECRGate(), 3),
         (CRXGate(np.pi / 7), 1 + 2 * np.abs(np.sin(np.pi / 14))),
         (CRYGate(np.pi / 7), 1 + 2 * np.abs(np.sin(np.pi / 14))),
         (CRZGate(np.pi / 7), 1 + 2 * np.abs(np.sin(np.pi / 14))),
@@ -283,6 +286,19 @@ def test_qpdbasis_from_gate_unique_maps(
     def test_supported_gates(self):
         gates = supported_gates()
         self.assertEqual(
-            {"rxx", "ryy", "rzz", "crx", "cry", "crz", "cx", "cy", "cz", "ch", "csx"},
+            {
+                "rxx",
+                "ryy",
+                "rzz",
+                "crx",
+                "cry",
+                "crz",
+                "cx",
+                "cy",
+                "cz",
+                "ch",
+                "csx",
+                "ecr",
+            },
             gates,
         )

test/cutting/test_cutting_roundtrip.py

@@ -28,6 +28,7 @@
     CRXGate,
     CRYGate,
     CRZGate,
+    ECRGate,
     CSXGate,
 )
 from qiskit.extensions import UnitaryGate
@@ -55,6 +56,7 @@ def append_random_unitary(circuit: QuantumCircuit, qubits):
         [CYGate()],
         [CZGate()],
         [CHGate()],
+        [ECRGate()],
         [CSXGate()],
         [RYYGate(0.0)],
         [RZZGate(np.pi)],