From b896f4cab1b3f755001a28fbb9dcf4a0e69569b0 Mon Sep 17 00:00:00 2001
From: Jim Garrison <garrison@ibm.com>
Date: Tue, 27 Jun 2023 13:26:08 -0400
Subject: [PATCH] Add support for cut `CYGate`s and `CHGate`s (#290)

* Add support for cut `CYGate`s

* Fix release note syntax

* Add support for cut `CHGate`s

* Update docstring

* Fix number in docstring

* DRY
---
 circuit_knitting/cutting/qpd/qpd.py           | 25 +++++++++++++------
 .../additional-gates-f4ed6c0e8dc3a9be.yaml    |  6 +++++
 test/cutting/qpd/test_qpd.py                  |  4 ++-
 test/cutting/test_cutting_roundtrip.py        |  4 +++
 4 files changed, 31 insertions(+), 8 deletions(-)
 create mode 100644 releasenotes/notes/additional-gates-f4ed6c0e8dc3a9be.yaml

diff --git a/circuit_knitting/cutting/qpd/qpd.py b/circuit_knitting/cutting/qpd/qpd.py
index 995f5d781..6771798c0 100644
--- a/circuit_knitting/cutting/qpd/qpd.py
+++ b/circuit_knitting/cutting/qpd/qpd.py
@@ -37,7 +37,9 @@
     RYGate,
     RZGate,
     CXGate,
+    CYGate,
     CZGate,
+    CHGate,
     RXXGate,
     RYYGate,
     RZZGate,
@@ -191,7 +193,7 @@ def qpdbasis_from_gate(gate: Gate) -> QPDBasis:
     """
     Generate a QPDBasis object, given a supported operation.
 
-    This method currently supports 8 operations:
+    This method currently supports 10 operations:
         - :class:`~qiskit.circuit.library.RXXGate`
         - :class:`~qiskit.circuit.library.RYYGate`
         - :class:`~qiskit.circuit.library.RZZGate`
@@ -199,7 +201,9 @@ def qpdbasis_from_gate(gate: Gate) -> QPDBasis:
         - :class:`~qiskit.circuit.library.CRYGate`
         - :class:`~qiskit.circuit.library.CRZGate`
         - :class:`~qiskit.circuit.library.CXGate`
+        - :class:`~qiskit.circuit.library.CYGate`
         - :class:`~qiskit.circuit.library.CZGate`
+        - :class:`~qiskit.circuit.library.CHGate`
 
     Returns:
         The newly-instantiated :class:`QPDBasis` object
@@ -304,8 +308,8 @@ def _(gate: RXXGate | RYYGate | RZZGate | CRXGate | CRYGate | CRZGate):
     return QPDBasis(maps, coeffs)
 
 
-@_register_qpdbasis_from_gate("cz", "cx")
-def _(gate: CZGate | CXGate):
+@_register_qpdbasis_from_gate("cx", "cy", "cz", "ch")
+def _(gate: CXGate | CYGate | CZGate | CHGate):
     # Constructing a virtual two-qubit gate by sampling single-qubit operations - Mitarai et al
     # https://iopscience.iop.org/article/10.1088/1367-2630/abd7bc/pdf
     measurement_0 = [SdgGate(), QPDMeasure()]
@@ -323,12 +327,19 @@ def _(gate: CZGate | CXGate):
         ([ZGate()], measurement_1),
     ]
 
-    if gate.name == "cx":
-        # Modify `maps` to sandwich the target operations inside of Hadamards
+    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():
             if operations:
-                operations.insert(0, HGate())
-                operations.append(HGate())
+                if gate.name in ("cx", "cy"):
+                    operations.insert(0, HGate())
+                    operations.append(HGate())
+                    if gate.name == "cy":
+                        operations.insert(0, SdgGate())
+                        operations.append(SGate())
+                elif gate.name == "ch":
+                    operations.insert(0, RYGate(-np.pi / 4))
+                    operations.append(RYGate(np.pi / 4))
 
     coeffs = [0.5, 0.5, 0.5, -0.5, 0.5, -0.5]
 
diff --git a/releasenotes/notes/additional-gates-f4ed6c0e8dc3a9be.yaml b/releasenotes/notes/additional-gates-f4ed6c0e8dc3a9be.yaml
new file mode 100644
index 000000000..a69953cc8
--- /dev/null
+++ b/releasenotes/notes/additional-gates-f4ed6c0e8dc3a9be.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    This release adds support for additional cut gates:
+    - :class:`~qiskit.circuit.library.CHGate`
+    - :class:`~qiskit.circuit.library.CYGate`
diff --git a/test/cutting/qpd/test_qpd.py b/test/cutting/qpd/test_qpd.py
index 56f4fc555..144b2849d 100644
--- a/test/cutting/qpd/test_qpd.py
+++ b/test/cutting/qpd/test_qpd.py
@@ -282,4 +282,6 @@ def test_qpdbasis_from_gate_unique_maps(
 
     def test_supported_gates(self):
         gates = supported_gates()
-        self.assertEqual({"rxx", "ryy", "rzz", "crx", "cry", "crz", "cx", "cz"}, gates)
+        self.assertEqual(
+            {"rxx", "ryy", "rzz", "crx", "cry", "crz", "cx", "cy", "cz", "ch"}, gates
+        )
diff --git a/test/cutting/test_cutting_roundtrip.py b/test/cutting/test_cutting_roundtrip.py
index be6eeea13..be36cbacd 100644
--- a/test/cutting/test_cutting_roundtrip.py
+++ b/test/cutting/test_cutting_roundtrip.py
@@ -21,7 +21,9 @@
     RXXGate,
     RYYGate,
     RZZGate,
+    CHGate,
     CXGate,
+    CYGate,
     CZGate,
     CRXGate,
     CRYGate,
@@ -49,7 +51,9 @@ def append_random_unitary(circuit: QuantumCircuit, qubits):
 @pytest.fixture(
     params=[
         [CXGate()],
+        [CYGate()],
         [CZGate()],
+        [CHGate()],
         [RYYGate(0.0)],
         [RZZGate(np.pi)],
         [RXXGate(np.pi / 3)],