Addressing comments from CR

pennylane_lightning/lightning_tensor/lightning_tensor.py

@@ -80,15 +80,11 @@ class LightningTensor(Device):
 
     # So far we just consider the options for MPS simulator
     _device_options = (
-        "apply_reverse_lightcone",
         "backend",
         "c_dtype",
         "cutoff",
         "method",
         "max_bond_dim",
-        "measure_algorithm",
-        "return_tn",
-        "rehearse",
     )
 
     _new_API = True
@@ -112,7 +108,7 @@ def __init__(
             raise ValueError(f"Unsupported method: {method}")
 
         if shots is not None:
-            raise ValueError("LightningTensor does not support the `shots` parameter.")
+            raise ValueError("LightningTensor does not support finite shots.")
 
         super().__init__(wires=wires, shots=shots)
 
@@ -124,12 +120,6 @@ def __init__(
         # options for MPS
         self._max_bond_dim = kwargs.get("max_bond_dim", None)
         self._cutoff = kwargs.get("cutoff", 1e-16)
-        self._measure_algorithm = kwargs.get("measure_algorithm", None)
-
-        # common options (MPS and TN)
-        self._return_tn = kwargs.get("return_tn", False)
-        self._rehearse = kwargs.get("rehearse", False)
-        self._apply_reverse_lightcone = kwargs.get("apply_reverse_lightcone", None)
 
         self._interface = None
         interface_opts = self._setup_execution_config().device_options
@@ -253,8 +243,7 @@ def supports_derivatives(
             Bool: Whether or not a derivative can be calculated provided the given information.
 
         """
-        # TODO: implement during next quarter
-        return False  # pragma: no cover
+        return False
 
     def compute_derivatives(
         self,
@@ -272,7 +261,7 @@ def compute_derivatives(
         """
         raise NotImplementedError(
             "The computation of derivatives has yet to be implemented for the lightning.tensor device."
-        )  # pragma: no cover
+        )
 
     def execute_and_compute_derivatives(
         self,
@@ -290,7 +279,7 @@ def execute_and_compute_derivatives(
         """
         raise NotImplementedError(
             "The computation of derivatives has yet to be implemented for the lightning.tensor device."
-        )  # pragma: no cover
+        )
 
     # pylint: disable=unused-argument
     def supports_vjp(
@@ -308,7 +297,7 @@ def supports_vjp(
             Bool: Whether or not a derivative can be calculated provided the given information.
         """
         # TODO: implement during next quarter
-        return False  # pragma: no cover
+        return False
 
     def compute_vjp(
         self,
@@ -330,7 +319,7 @@ def compute_vjp(
         """
         raise NotImplementedError(
             "The computation of vector jacobian product has yet to be implemented for the lightning.tensor device."
-        )  # pragma: no cover
+        )
 
     def execute_and_compute_vjp(
         self,
@@ -351,4 +340,4 @@ def execute_and_compute_vjp(
         """
         raise NotImplementedError(
             "The computation of vector jacobian product has yet to be implemented for the lightning.tensor device."
-        )  # pragma: no cover
+        )

pennylane_lightning/lightning_tensor/quimb/_mps.py

@@ -56,7 +56,6 @@ def __init__(self, num_wires, interf_opts, dtype=np.complex128):
 
         self._wires = Wires(range(num_wires))
         self._dtype = dtype
-        self._return_tn = interf_opts["return_tn"]
 
         self._init_state_ops = {
             "binary": "0" * max(1, len(self._wires)),
@@ -75,7 +74,6 @@ def __init__(self, num_wires, interf_opts, dtype=np.complex128):
             "dtype": self._dtype.__name__,
             "simplify_sequence": "ADCRS",
             "simplify_atol": 0.0,
-            "rehearse": interf_opts["rehearse"],
         }
 
         self._circuitMPS = qtn.CircuitMPS(psi0=self._initial_mps())

tests/lightning_tensor/test_lightning_tensor.py

@@ -27,8 +27,8 @@
 if not LightningDevice._new_API:
     pytest.skip("Exclusive tests for new API. Skipping.", allow_module_level=True)
 
-if LightningDevice._CPP_BINARY_AVAILABLE:
-    pytest.skip("Device doesn't have C++ support yet.", allow_module_level=True)
+# if LightningDevice._CPP_BINARY_AVAILABLE:
+#    pytest.skip("Device doesn't have C++ support yet.", allow_module_level=True)
 
 
 @pytest.mark.parametrize("num_wires", [None, 4])
@@ -71,5 +71,45 @@ def test_invalid_keyword_arg():
 
 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 the `shots` parameter."):
+    with pytest.raises(ValueError, match="LightningTensor does not support finite shots."):
         LightningTensor(shots=5)
+
+
+def test_support_derivatives():
+    """Test that the device does not support derivatives yet."""
+    dev = LightningTensor()
+    assert not dev.supports_derivatives()
+
+
+def test_compute_derivatives():
+    """Test that an error is raised if the `compute_derivatives` method is called."""
+    dev = LightningTensor()
+    with pytest.raises(NotImplementedError):
+        dev.compute_derivatives(circuits=None)
+
+
+def test_execute_and_compute_derivatives():
+    """Test that an error is raised if `execute_and_compute_derivative` method is called."""
+    dev = LightningTensor()
+    with pytest.raises(NotImplementedError):
+        dev.execute_and_compute_derivatives(circuits=None)
+
+
+def test_supports_vjp():
+    """Test that the device does not support VJP yet."""
+    dev = LightningTensor()
+    assert not dev.supports_vjp()
+
+
+def test_compute_vjp():
+    """Test that an error is raised if `compute_vjp` method is called."""
+    dev = LightningTensor()
+    with pytest.raises(NotImplementedError):
+        dev.compute_vjp(circuits=None, cotangents=None)
+
+
+def test_execute_and_compute_vjp():
+    """Test that an error is raised if `execute_and_compute_vjp` method is called."""
+    dev = LightningTensor()
+    with pytest.raises(NotImplementedError):
+        dev.execute_and_compute_vjp(circuits=None, cotangents=None)

tests/lightning_tensor/test_quimb_mps.py

@@ -27,8 +27,8 @@
 if not LightningDevice._new_API:
     pytest.skip("Exclusive tests for new API. Skipping.", allow_module_level=True)
 
-if LightningDevice._CPP_BINARY_AVAILABLE:
-    pytest.skip("Device doesn't have C++ support yet.", allow_module_level=True)
+# if LightningDevice._CPP_BINARY_AVAILABLE:
+#    pytest.skip("Device doesn't have C++ support yet.", allow_module_level=True)
 
 
 @pytest.mark.parametrize("backend", ["quimb"])