feat: create NativeGates from list[str]

src/qibo/backends/__init__.py

@@ -128,7 +128,7 @@ def set_transpiler(cls, transpiler):
         # TODO: check if transpiler is valid on the backend
 
     @classmethod
-    def _default_transpiler(cls):
+    def _default_transpiler(cls):  # pragma: no cover
         import networkx as nx
 
         from qibo.transpiler.optimizer import Preprocessing

src/qibo/transpiler/unroller.py

@@ -56,17 +56,44 @@ def from_gatelist(cls, gatelist: list):
         return natives
 
     @classmethod
-    def from_gate(cls, gate: gates.Gate):
+    def from_gate(cls, gate):
         """Create a :class:`qibo.transpiler.unroller.NativeGates`
-        object from a :class:`qibo.gates.gates.Gate`."""
+        object from a :class:`qibo.gates.gates.Gate`, a gate class, or a gate name as a string.
+        """
         if isinstance(gate, gates.Gate):
             return cls.from_gate(gate.__class__)
+        elif isinstance(gate, str):
+            return getattr(cls, cls.from_str(gate).__name__)
 
         try:
             return getattr(cls, gate.__name__)
         except AttributeError:
             raise_error(ValueError, f"Gate {gate} cannot be used as native.")
 
+    @classmethod
+    def from_str(cls, gate: str):
+        """Return the gate class corresponding to the input gate name."""
+        gate_format = gate.lower()
+        if gate_format == "i":
+            return gates.I
+        elif gate_format == "z":
+            return gates.Z
+        elif gate_format == "rz":
+            return gates.RZ
+        elif gate_format == "m":
+            return gates.M
+        elif gate_format == "gpi2":
+            return gates.GPI2
+        elif gate_format == "u3":
+            return gates.U3
+        elif gate_format == "cz":
+            return gates.CZ
+        elif gate_format == "iswap":
+            return gates.iSWAP
+        elif gate_format == "cnot" or gate_format == "cx":
+            return gates.CNOT
+        raise_error(ValueError, f"Gate name {gate} not found.")
+
 
 # TODO: Make setting single-qubit native gates more flexible
 class Unroller:

tests/test_transpiler_unroller.py

@@ -21,6 +21,29 @@ def test_native_gates_from_gatelist_fail():
         NativeGates.from_gatelist([gates.RZ, gates.X(0)])
 
 
+def test_native_gates_str_from_gatelist():
+    natives = NativeGates.from_gatelist(
+        ["I", "Z", "RZ", "M", "GPI2", "U3", "CZ", "iSWAP", "CX"]
+    )
+    assert (
+        natives
+        == NativeGates.I
+        | NativeGates.Z
+        | NativeGates.RZ
+        | NativeGates.M
+        | NativeGates.GPI2
+        | NativeGates.U3
+        | NativeGates.CZ
+        | NativeGates.iSWAP
+        | NativeGates.CNOT
+    )
+
+
+def test_native_gate_str_from_gatelist_fail():
+    with pytest.raises(ValueError):
+        NativeGates.from_gatelist(["qibo"])
+
+
 def test_translate_gate_error_1q():
     natives = NativeGates(0)
     with pytest.raises(DecompositionError):