Support basic single qubit controlled gates (#89)

* Support basic single qubit controlled gates
- The single controlled gate sets are supported but requires a slight modification
- The multicontrolled gates can be considered in future versions

* Lint fixes

* Remove string based comparision and move to dict

* Add test cases

* Lint: Single qubit gates

* Update tests/pyquil_convert_test.py

---------

Co-authored-by: cqc-melf <[email protected]>

pytket/extensions/pyquil/pyquil_convert.py

@@ -71,11 +71,16 @@
     "PHASE": OpType.U1,
     "SWAP": OpType.SWAP,
     "XY": OpType.ISWAP,
+    "CH": OpType.CH,
+    "CY": OpType.CY,
 }
 
 
 _known_quil_gate_rev = {v: k for k, v in _known_quil_gate.items()}
 
+# Gates with single controlled operation
+_single_control_gates = {"CH": "H", "CY": "Y"}
+
 
 def param_to_pyquil(p: Union[float, Expr]) -> Union[float, Expression]:
     ppi = p * pi
@@ -302,7 +307,13 @@ def tk_to_pyquil(
                 "Cannot convert tket Op to pyQuil gate: " + op.get_name()
             ) from error
         params = [param_to_pyquil(p) for p in op.params]
-        g = Gate(gatetype, params, qubits)
+        if gatetype in _single_control_gates:
+            g = Gate(_single_control_gates[gatetype], params, [qubits[1]]).controlled(
+                qubits[0]
+            )
+        else:
+            g = Gate(gatetype, params, qubits)
+
         p += g
     for m in measures:
         p += m

tests/pyquil_convert_test.py

@@ -132,6 +132,29 @@ def test_from_tket() -> None:
     )  # 5 gates, 2 measures, and an initial declaration of classical register
 
 
+def test_conversion_of_controlled_y() -> None:
+    single_controlled_gates_attributes = [
+        {"name": "Y", "qubits": [0, 1]},
+        {"name": "H", "qubits": [1, 0]},
+    ]
+    c = Circuit(2, 2)
+    c.CY(*single_controlled_gates_attributes[0]["qubits"])
+    c.CH(*single_controlled_gates_attributes[1]["qubits"])
+
+    p = tk_to_pyquil(c)
+
+    for i, attributes in enumerate(single_controlled_gates_attributes):
+        Instruction = p.instructions[i + 1]
+        for attribute in attributes:
+            expected_attribute_value = attributes[attribute]
+            value = getattr(Instruction, attribute)
+            if attribute == "qubits":
+                for i, expected_qubit_index in enumerate(expected_attribute_value):
+                    assert value[i].index == expected_qubit_index
+            else:
+                assert value == expected_attribute_value
+
+
 def test_measure() -> None:
     p = get_test_program(True)
     m_map = {}