Add default.tensor to setup.py (#719)

* Update setup for default.tensor

* Added test

* Auto update version from '0.37.0-dev3' to '0.37.0-dev4'

* Update changelog

* Update setup.py

* Update per review

* Updated docstrings

* Auto update version from '0.37.0-dev4' to '0.37.0-dev5'

* [skip ci] Skip CI

* Auto update version from '0.37.0-dev5' to '0.37.0-dev6'

---------

Co-authored-by: ringo-but-quantum <github-ringo-but-quantum@xanadu.ai>

.github/CHANGELOG.md

@@ -18,6 +18,9 @@
 * Add support for `qml.expval` and `qml.var` in the `lightning.tensor` device for the `quimb` interface and the MPS method.
   [(#686)](https://github.com/PennyLaneAI/pennylane-lightning/pull/686)  
 
+* Changed the name of `lightning.tensor` to `default.tensor` with the `quimb` backend.
+  [(#719)](https://github.com/PennyLaneAI/pennylane-lightning/pull/719)
+
 ### Documentation
 
 ### Bug fixes
@@ -26,7 +29,7 @@
 
 This release contains contributions from (in alphabetical order):
 
-Amintor Dusko, Pietropaolo Frisoni, Vincent Michaud-Rioux
+Amintor Dusko, Pietropaolo Frisoni, Vincent Michaud-Rioux, Mudit Pandey
 
 ---
 

pennylane_lightning/core/_version.py

@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.37.0-dev5"
+__version__ = "0.37.0-dev6"

pennylane_lightning/lightning_tensor/backends/quimb/_mps.py

@@ -116,12 +116,12 @@
 
 
 def stopping_condition(op: qml.operation.Operator) -> bool:
-    """A function that determines if an operation is supported by ``lightning.tensor`` for this interface."""
+    """A function that determines if an operation is supported by ``default.tensor`` for this interface."""
     return op.name in _operations  # pragma: no cover
 
 
 def accepted_observables(obs: qml.operation.Operator) -> bool:
-    """A function that determines if an observable is supported by ``lightning.tensor`` for this interface."""
+    """A function that determines if an observable is supported by ``default.tensor`` for this interface."""
     return obs.name in _observables  # pragma: no cover
 
 

pennylane_lightning/lightning_tensor/lightning_tensor.py

@@ -42,12 +42,12 @@
 
 
 def accepted_backends(backend: str) -> bool:
-    """A function that determines whether or not a backend is supported by ``lightning.tensor``."""
+    """A function that determines whether or not a backend is supported by ``default.tensor``."""
     return backend in _backends
 
 
 def accepted_methods(method: str) -> bool:
-    """A function that determines whether or not a method is supported by ``lightning.tensor``."""
+    """A function that determines whether or not a method is supported by ``default.tensor``."""
     return method in _methods
 
 
@@ -111,7 +111,7 @@ def __init__(
             raise ValueError(f"Unsupported method: {method}")
 
         if shots is not None:
-            raise ValueError("LightningTensor does not support finite shots.")
+            raise ValueError("default.tensor does not support finite shots.")
 
         super().__init__(wires=wires, shots=shots)
 
@@ -143,13 +143,13 @@ def __init__(
         for arg in kwargs:
             if arg not in self._device_options:
                 raise TypeError(
-                    f"Unexpected argument: {arg} during initialization of the LightningTensor device."
+                    f"Unexpected argument: {arg} during initialization of the default.tensor device."
                 )
 
     @property
     def name(self):
         """The name of the device."""
-        return "lightning.tensor"
+        return "default.tensor"
 
     @property
     def num_wires(self):
@@ -266,7 +266,7 @@ def compute_derivatives(
             Tuple: The Jacobian for each trainable parameter.
         """
         raise NotImplementedError(
-            "The computation of derivatives has yet to be implemented for the lightning.tensor device."
+            "The computation of derivatives has yet to be implemented for the default.tensor device."
         )
 
     def execute_and_compute_derivatives(
@@ -284,7 +284,7 @@ def execute_and_compute_derivatives(
             tuple: A numeric result of the computation and the gradient.
         """
         raise NotImplementedError(
-            "The computation of derivatives has yet to be implemented for the lightning.tensor device."
+            "The computation of derivatives has yet to be implemented for the default.tensor device."
         )
 
     # pylint: disable=unused-argument
@@ -323,7 +323,7 @@ def compute_vjp(
             tensor-like: A numeric result of computing the vector-Jacobian product.
         """
         raise NotImplementedError(
-            "The computation of vector-Jacobian product has yet to be implemented for the lightning.tensor device."
+            "The computation of vector-Jacobian product has yet to be implemented for the default.tensor device."
         )
 
     def execute_and_compute_vjp(
@@ -344,5 +344,5 @@ def execute_and_compute_vjp(
             Tuple, Tuple: the result of executing the scripts and the numeric result of computing the vector-Jacobian product
         """
         raise NotImplementedError(
-            "The computation of vector-Jacobian product has yet to be implemented for the lightning.tensor device."
+            "The computation of vector-Jacobian product has yet to be implemented for the default.tensor device."
         )

setup.py

@@ -177,7 +177,7 @@ def build_extension(self, ext: CMakeExtension):
 packages_list = ["pennylane_lightning." + backend]
 
 if backend == "lightning_qubit":
-    packages_list += ["pennylane_lightning.core"]
+    packages_list += ["pennylane_lightning.core", "pennylane_lightning.lightning_tensor"]
 else:
     requirements += ["pennylane_lightning==" + version]
 
@@ -187,6 +187,10 @@ def build_extension(self, ext: CMakeExtension):
 suffix = suffix[0].upper() + suffix[1:]
 
 pennylane_plugins = [device_name + " = pennylane_lightning." + backend + ":Lightning" + suffix]
+if suffix == "Qubit":
+    pennylane_plugins.append(
+        "default.tensor = pennylane_lightning.lightning_tensor:LightningTensor"
+    )
 
 pkg_suffix = "" if suffix == "Qubit" else "_" + suffix
 
@@ -222,7 +226,11 @@ def build_extension(self, ext: CMakeExtension):
                 "pennylane_lightning.core": [
                     os.path.join("src", "*"),
                     os.path.join("src", "**", "*"),
-                ]
+                ],
+                "pennylane_lightning.lightning_tensor": [
+                    os.path.join("backends", "*"),
+                    os.path.join("backends", "**", "*"),
+                ],
             },
         }
     )

tests/lightning_tensor/test_lightning_tensor.py

@@ -37,7 +37,7 @@ def test_device_name_and_init(num_wires, c_dtype):
     """Test the class initialization and returned properties."""
     wires = Wires(range(num_wires)) if num_wires else None
     dev = LightningTensor(wires=wires, c_dtype=c_dtype)
-    assert dev.name == "lightning.tensor"
+    assert dev.name == "default.tensor"
     assert dev.c_dtype == c_dtype
     assert dev.wires == wires
     if num_wires is None:
@@ -46,6 +46,12 @@ def test_device_name_and_init(num_wires, c_dtype):
         assert dev.num_wires == num_wires
 
 
+def test_device_available_as_plugin():
+    """Test that the device can be instantiated using ``qml.device``."""
+    dev = qml.device("default.tensor", wires=2)
+    assert isinstance(dev, LightningTensor)
+
+
 @pytest.mark.parametrize("backend", ["fake_backend"])
 def test_invalid_backend(backend):
     """Test an invalid backend."""
@@ -64,14 +70,14 @@ def test_invalid_keyword_arg():
     """Test an invalid keyword argument."""
     with pytest.raises(
         TypeError,
-        match=f"Unexpected argument: fake_arg during initialization of the LightningTensor device.",
+        match=f"Unexpected argument: fake_arg during initialization of the default.tensor device.",
     ):
         LightningTensor(fake_arg=None)
 
 
 def test_invalid_shots():
     """Test that an error is raised if finite number of shots are requestd."""
-    with pytest.raises(ValueError, match="LightningTensor does not support finite shots."):
+    with pytest.raises(ValueError, match="default.tensor does not support finite shots."):
         LightningTensor(shots=5)
 
 
@@ -86,7 +92,7 @@ def test_compute_derivatives():
     dev = LightningTensor()
     with pytest.raises(
         NotImplementedError,
-        match="The computation of derivatives has yet to be implemented for the lightning.tensor device.",
+        match="The computation of derivatives has yet to be implemented for the default.tensor device.",
     ):
         dev.compute_derivatives(circuits=None)
 
@@ -96,7 +102,7 @@ def test_execute_and_compute_derivatives():
     dev = LightningTensor()
     with pytest.raises(
         NotImplementedError,
-        match="The computation of derivatives has yet to be implemented for the lightning.tensor device.",
+        match="The computation of derivatives has yet to be implemented for the default.tensor device.",
     ):
         dev.execute_and_compute_derivatives(circuits=None)
 
@@ -112,7 +118,7 @@ def test_compute_vjp():
     dev = LightningTensor()
     with pytest.raises(
         NotImplementedError,
-        match="The computation of vector-Jacobian product has yet to be implemented for the lightning.tensor device.",
+        match="The computation of vector-Jacobian product has yet to be implemented for the default.tensor device.",
     ):
         dev.compute_vjp(circuits=None, cotangents=None)
 
@@ -122,6 +128,6 @@ def test_execute_and_compute_vjp():
     dev = LightningTensor()
     with pytest.raises(
         NotImplementedError,
-        match="The computation of vector-Jacobian product has yet to be implemented for the lightning.tensor device.",
+        match="The computation of vector-Jacobian product has yet to be implemented for the default.tensor device.",
     ):
         dev.execute_and_compute_vjp(circuits=None, cotangents=None)