feat: implemented metabackend

src/qibotn/__init__.py

@@ -1,3 +1,5 @@
 import importlib.metadata as im
 
+from qibotn.backends import MetaBackend
+
 __version__ = im.version(__package__)

src/qibotn/backends/__init__.py

@@ -0,0 +1,45 @@
+from typing import Union
+
+from qibotn.backends.cutensornet import CuTensorNet  # pylint: disable=E0401
+from qibotn.backends.quimb import QuimbBackend  # pylint: disable=E0401
+
+QibotnBackend = Union[CuTensorNet, QuimbBackend]
+
+PLATFORMS = ("cutensornet", "qutensornet")
+
+
+class MetaBackend:
+    """Meta-backend class which takes care of loading the qibotn backends."""
+
+    @staticmethod
+    def load(platform: str, runcard: dict = None) -> QibotnBackend:
+        """Loads the backend.
+
+        Args:
+            platform (str): Name of the backend to load: either `cutensornet` or `qutensornet`.
+            runcard (dict): Dictionary containing the simulation settings.
+        Returns:
+            qibo.backends.abstract.Backend: The loaded backend.
+        """
+
+        if platform == "cutensornet":  # pragma: no cover
+            return CuTensorNet(runcard)
+        elif platform == "qutensornet":  # pragma: no cover
+            return QuimbBackend(runcard)
+        else:
+            raise_error(
+                NotImplementedError,
+                f"Unsupported platform {platform}, please pick one in (`cutensornet`, `qutensornet)",
+            )
+
+    def list_available(self) -> dict:
+        """Lists all the available qibotn backends."""
+        available_backends = {}
+        for platform in PLATFORMS:
+            try:
+                MetaBackend.load(platform=platform)
+                available = True
+            except:
+                available = False
+            available_backends[platform] = available
+        return available_backends