Daily rc sync to master (#5953)

Automatic sync from the release candidate to master during a feature
freeze.

---------

Co-authored-by: Jay Soni <jbsoni@uwaterloo.ca>
Co-authored-by: Astral Cai <astral.cai@xanadu.ai>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Yushao Chen (Jerry) <chenys13@outlook.com>
Co-authored-by: Christina Lee <chrissie.c.l@gmail.com>
Co-authored-by: Mudit Pandey <mudit.pandey@xanadu.ai>
Co-authored-by: Thomas R. Bromley <49409390+trbromley@users.noreply.github.com>
Co-authored-by: soranjh <40344468+soranjh@users.noreply.github.com>
Co-authored-by: Pietropaolo Frisoni <pietropaolo.frisoni@xanadu.ai>
Co-authored-by: Isaac De Vlugt <34751083+isaacdevlugt@users.noreply.github.com>
Co-authored-by: GitHub Actions Bot <>

doc/development/guide/installation.rst

@@ -67,7 +67,7 @@ importing PennyLane in Python.
     requires ``pip install -e .`` to be re-run in the plugin repository
     for the changes to take effect.
 
-Apart from the core packages needed to run PennyLane. Some extra packages need
+Apart from the core packages needed to run PennyLane, some extra packages need
 to be installed for several development processes, such as linting, testing, and
 pre-commit quality checks. Those can be installed easily via ``pip``:
 

doc/releases/changelog-0.37.0.md

@@ -430,7 +430,7 @@
   [(#5654)](https://github.com/PennyLaneAI/pennylane/pull/5654)
 
 * `qml.transforms.convert_to_numpy_parameters` is now a proper transform and its output signature has changed,
-  returning a list of `QuantumTape`s and a post-processing function instead of simply the transformed circuit.
+  returning a list of `QuantumScript`s and a post-processing function instead of simply the transformed circuit.
   [(#5693)](https://github.com/PennyLaneAI/pennylane/pull/5693)
 
 * `Controlled.wires` does not include `self.work_wires` anymore. That can be accessed separately through `Controlled.work_wires`.
@@ -452,6 +452,9 @@
 
 <h3>Documentation 📝</h3>
 
+* Several links to other functions in measurement process docstrings have been fixed.
+  [(#5913)](https://github.com/PennyLaneAI/pennylane/pull/5913)
+
 * Move information about mid-circuit measurements from the measurements quickstart page to its own
   [mid-circuit measurements quickstart page](https://docs.pennylane.ai/en/stable/introduction/mid_circuit_measurements.html)
   [(#5870)](https://github.com/PennyLaneAI/pennylane/pull/5870)
@@ -509,7 +512,7 @@
 * An error is now raised if a transform is applied to a catalyst qjit object.
   [(#5826)](https://github.com/PennyLaneAI/pennylane/pull/5826)
 
-* `KerasLayer` and `TorchLayer` no longer mutate the input `QNode`'s interface.
+* `qml.qnn.KerasLayer` and `qml.qnn.TorchLayer` no longer mutate the input `qml.QNode`'s interface.
   [(#5800)](https://github.com/PennyLaneAI/pennylane/pull/5800)
 
 * Disable Docker builds on PR merge.

pennylane/capture/capture_meta.py

@@ -32,6 +32,8 @@ class CaptureMeta(type):
 
     .. code-block::
 
+        qml.capture.enable()
+
         class AbstractMyObj(jax.core.AbstractValue):
             pass
 

pennylane/capture/capture_qnode.py

@@ -94,7 +94,7 @@ def qnode_call(qnode: "qml.QNode", *args, **kwargs) -> "qml.typing.Result":
         args: the arguments the QNode is called with
 
     Keyword Args:
-        Any keyword arguments accepted by the quantum function
+        kwargs (Any): Any keyword arguments accepted by the quantum function
 
     Returns:
         qml.typing.Result: the result of a qnode execution
@@ -103,14 +103,16 @@ def qnode_call(qnode: "qml.QNode", *args, **kwargs) -> "qml.typing.Result":
 
     .. code-block:: python
 
+        qml.capture.enable()
+
         @qml.qnode(qml.device('lightning.qubit', wires=1))
         def circuit(x):
             qml.RX(x, wires=0)
             return qml.expval(qml.Z(0)), qml.probs()
 
         def f(x):
-            expval_z, probs = circuit(np.pi * x, shots=50)
-            return 2*expval_z + probs
+            expval_z, probs = circuit(np.pi * x, shots=50000)
+            return 2 * expval_z + probs
 
         jaxpr = jax.make_jaxpr(f)(0.1)
         print("jaxpr:")
@@ -128,22 +130,23 @@ def f(x):
         { lambda ; a:f32[]. let
             b:f32[] = mul 3.141592653589793 a
             c:f32[] d:f32[2] = qnode[
-            device=<lightning.qubit device (wires=1) at 0x107639010>
-            qfunc_jaxpr={ lambda ; e:f32[]. let
-                _:AbstractOperator() = RX[n_wires=1] e 0
-                f:AbstractOperator() = PauliZ[n_wires=1] 0
-                g:AbstractMeasurement(n_wires=None) = expval_obs f
-                h:AbstractMeasurement(n_wires=0) = probs_wires
+              device=<lightning.qubit device (wires=1) at 0x10557a070>
+              qfunc_jaxpr={ lambda ; e:f32[]. let
+                  _:AbstractOperator() = RX[n_wires=1] e 0
+                  f:AbstractOperator() = PauliZ[n_wires=1] 0
+                  g:AbstractMeasurement(n_wires=None) = expval_obs f
+                  h:AbstractMeasurement(n_wires=0) = probs_wires
                 in (g, h) }
-            qnode_kwargs={'diff_method': 'best', 'grad_on_execution': 'best', 'cache': False, 'cachesize': 10000, 'max_diff': 1, 'max_expansion': 10, 'device_vjp': False}
-            shots=Shots(total=50)
+              qnode=<QNode: device='<lightning.qubit device (wires=1) at 0x10557a070>', interface='auto', diff_method='best'>
+              qnode_kwargs={'diff_method': 'best', 'grad_on_execution': 'best', 'cache': False, 'cachesize': 10000, 'max_diff': 1, 'max_expansion': 10, 'device_vjp': False, 'mcm_method': None, 'postselect_mode': None}
+              shots=Shots(total=50000)
             ] b
             i:f32[] = mul 2.0 c
             j:f32[2] = add i d
-        in (j,) }
+          in (j,) }
 
         result:
-        [Array([-1.3 , -0.74], dtype=float32)]
+        [Array([-0.96939224, -0.38207346], dtype=float32)]
 
 
     """

pennylane/capture/explanations.md

@@ -178,7 +178,7 @@ Great!👍
 
 Now you can see that the problem is that we lied in our definition of abstract evaluation.  Jax thinks that `PrimitiveClass` returns something of shape `(1,)` and type `float32`.
 
-But jax doesn't have an abstract type that really describes "PrimitiveClass".  So we need to define an register our own.
+But jax doesn't have an abstract type that really describes "PrimitiveClass".  So we need to define and register our own.
 
 
 ```python

pennylane/debugging/snapshot.py

@@ -123,12 +123,15 @@ def circuit():
     {0: array([0.70710678+0.j, 0.        +0.j, 0.70710678+0.j, 0.        +0.j]),
     'execution_results': {'00': 101, '11': 99}}
 
-    Here one can see how a device that does not natively support snapshots executes two different circuits:
+    Here one can see how a device that does not natively support snapshots executes two different circuits. Additionally, a warning
+    is raised along with the results:
 
     .. code-block:: python3
 
+        dev = qml.device("lightning.qubit", shots=100, wires=2)
+
         @qml.snapshots
-        @qml.qnode(qml.device("lightning.qubit", shots=100, wires=2), diff_method="parameter-shift")
+        @qml.qnode(dev)
         def circuit():
             qml.Hadamard(wires=0),
             qml.Snapshot(qml.counts())
@@ -139,10 +142,18 @@ def circuit():
             out = circuit()
 
     >>> circuit.device.tracker.totals
-    {'batches': 1, 'simulations': 2, 'executions': 2, 'results': 0.0}
+    UserWarning: Snapshots are not supported for the given device. Therefore, a tape will be created for each snapshot, resulting in a total of n_snapshots + 1 executions.
+      warnings.warn(
+    {'batches': 1,
+     'simulations': 2,
+     'executions': 2,
+     'shots': 200,
+     'results': -0.16}
 
     >>> out
-    {0: {'00': tensor(51, requires_grad=True), '10': tensor(49, requires_grad=True)}, 'execution_results': tensor(0., requires_grad=True)}
+    {0: {'00': tensor(52, requires_grad=True),
+      '10': tensor(48, requires_grad=True)},
+     'execution_results': tensor(-0.1, requires_grad=True)}
 
     Here you can see the default behaviour of the transform for unsupported devices and you can see how the amount of wires included
     in each resulting tape is minimal:
@@ -194,13 +205,6 @@ def circuit():
     def postprocessing_fn(results, snapshot_tags):
         return dict(zip(snapshot_tags, results))
 
-    if len(new_tapes) > 1:
-        warnings.warn(
-            "Snapshots are not supported for the given device. Therefore, a tape will be "
-            f"created for each snapshot, resulting in a total of {len(new_tapes)} executions.",
-            UserWarning,
-        )
-
     return new_tapes, partial(postprocessing_fn, snapshot_tags=snapshot_tags)
 
 
@@ -240,4 +244,10 @@ def get_snapshots(*args, **kwargs):
     if _is_snapshot_compatible(qnode.device):
         return get_snapshots
 
+    warnings.warn(
+        "Snapshots are not supported for the given device. Therefore, a tape will be "
+        "created for each snapshot, resulting in a total of n_snapshots + 1 executions.",
+        UserWarning,
+    )
+
     return self.default_qnode_transform(qnode, targs, tkwargs)

pennylane/devices/__init__.py

@@ -57,6 +57,7 @@
     MCMConfig
     Device
     DefaultQubit
+    DefaultTensor
     NullQubit
     DefaultQutritMixed
 
@@ -160,6 +161,7 @@ def execute(self, circuits, execution_config = qml.devices.DefaultExecutionConfi
 from .default_gaussian import DefaultGaussian
 from .default_mixed import DefaultMixed
 from .default_clifford import DefaultClifford
+from .default_tensor import DefaultTensor
 from .null_qubit import NullQubit
 from .default_qutrit_mixed import DefaultQutritMixed
 from .._device import Device as LegacyDevice

pennylane/devices/default_tensor.py

@@ -54,6 +54,9 @@
 PostprocessingFn = Callable[[ResultBatch], Result_or_ResultBatch]
 
 has_quimb = True
+
+warnings.filterwarnings("ignore", message=".*kahypar")
+
 try:
     import quimb.tensor as qtn
 except (ModuleNotFoundError, ImportError) as import_error:  # pragma: no cover

pennylane/devices/preprocess.py

@@ -260,7 +260,7 @@ def validate_adjoint_trainable_params(
 
 @transform
 def decompose(
-    tape: qml.tape.QuantumTape,
+    tape: qml.tape.QuantumScript,
     stopping_condition: Callable[[qml.operation.Operator], bool],
     stopping_condition_shots: Callable[[qml.operation.Operator], bool] = None,
     skip_initial_state_prep: bool = True,
@@ -274,34 +274,36 @@ def decompose(
     """Decompose operations until the stopping condition is met.
 
     Args:
-        tape (QuantumTape or QNode or Callable): a quantum circuit.
-        stopping_condition (Callable): a function from an operator to a boolean. If ``False``, the operator
-            should be decomposed. If an operator cannot be decomposed and is not accepted by ``stopping_condition``,
-            an ``Exception`` will be raised (of a type specified by the ``error`` kwarg).
+        tape (QuantumScript or QNode or Callable): a quantum circuit.
+        stopping_condition (Callable): a function from an operator to a boolean. If ``False``,
+            the operator should be decomposed. If an operator cannot be decomposed and is not
+            accepted by ``stopping_condition``, an ``Exception`` will be raised (of a type
+            specified by the ``error`` keyward argument).
 
     Keyword Args:
-        stopping_condition_shots (Callable): a function from an operator to a boolean. If ``False``, the operator
-            should be decomposed. If an operator cannot be decomposed and is not accepted by ``stopping_condition``,
-            an ``Exception`` will be raised (of a type specified by the ``error`` kwarg). This replaces stopping_condition if and only if the tape has shots.
-        skip_initial_state_prep (bool): If ``True``, the first operator will not be decomposed if it inherits
-            from :class:`~.StatePrepBase`. Defaults to ``True``.
-        decomposer (Callable): an optional callable that takes an operator and implements the relevant decomposition.
-            If None, defaults to using a callable returning ``op.decomposition()`` for any :class:`~.Operator` .
+        stopping_condition_shots (Callable): a function from an operator to a boolean. If
+            ``False``, the operator should be decomposed. This replaces ``stopping_condition``
+            if and only if the tape has shots.
+        skip_initial_state_prep (bool): If ``True``, the first operator will not be decomposed if
+            it inherits from :class:`~.StatePrepBase`. Defaults to ``True``.
+        decomposer (Callable): an optional callable that takes an operator and implements the
+            relevant decomposition. If ``None``, defaults to using a callable returning
+            ``op.decomposition()`` for any :class:`~.Operator` .
         max_expansion (int): The maximum depth of the expansion. Defaults to None.
-        name (str): The name of the transform, process or device using decompose. Used in the error message. Defaults to "device".
-        error (Error): An error type to raise if it is not possible to obtain a decomposition that fulfills
-            the ``stopping_condition``. Defaults to ``DeviceError``.
-
+        name (str): The name of the transform, process or device using decompose. Used in the
+            error message. Defaults to "device".
+        error (type): An error type to raise if it is not possible to obtain a decomposition that
+            fulfills the ``stopping_condition``. Defaults to ``DeviceError``.
 
     Returns:
-        qnode (QNode) or quantum function (Callable) or tuple[List[QuantumTape], function]:
+        qnode (QNode) or quantum function (Callable) or tuple[List[QuantumScript], function]:
 
         The decomposed circuit. The output type is explained in :func:`qml.transform <pennylane.transform>`.
 
     Raises:
-        Exception: Type defaults to ``DeviceError`` but can be modified via keyword argument. Raised if
-            an operator is not accepted and does not define a decomposition, or if the decomposition
-            enters an infinite loop and raises a ``RecursionError``.
+        Exception: Type defaults to ``DeviceError`` but can be modified via keyword argument.
+            Raised if an operator is not accepted and does not define a decomposition, or if
+            the decomposition enters an infinite loop and raises a ``RecursionError``.
 
     **Example:**
 
@@ -320,7 +322,7 @@ def decompose(
     >>> decompose(tape, lambda obj: obj.name == "S")
     DeviceError: Operator CNOT(wires=[0, 1]) not supported on device and does not provide a decomposition.
 
-    The ``skip_initial_state_prep`` specifies whether or not the device supports state prep operations
+    The ``skip_initial_state_prep`` specifies whether the device supports state prep operations
     at the beginning of the circuit.
 
     >>> tape = qml.tape.QuantumScript([qml.BasisState([1], wires=0), qml.BasisState([1], wires=1)])

pennylane/io.py

@@ -465,7 +465,7 @@ def from_qasm(quantum_circuit: str, measurements=False):
                          'measure q -> c;'
 
         dev = qml.device("default.qubit")
-        loaded_circuit = qml.from_qasm(hadamard_qasm)
+        loaded_circuit = qml.from_qasm(hadamard_qasm, measurements=None)
 
         @qml.qnode(dev)
         def circuit():
@@ -503,7 +503,13 @@ def circuit():
         function: the PennyLane template created based on the QASM string
 
     """
-    plugin_converter = plugin_converters["qasm"].load()
+    try:
+        plugin_converter = plugin_converters["qasm"].load()
+    except Exception as e:  # pragma: no cover
+        raise RuntimeError(  # pragma: no cover
+            "Failed to load the qasm plugin. Please ensure that the pennylane-qiskit package is installed."
+        ) from e
+
     if measurements is False:
         measurements = []
         if "measure" in quantum_circuit:

pennylane/measurements/classical_shadow.py

@@ -216,7 +216,7 @@ class ClassicalShadowMP(MeasurementTransform):
     """Represents a classical shadow measurement process occurring at the end of a
     quantum variational circuit.
 
-    Please refer to :func:`classical_shadow` for detailed documentation.
+    Please refer to :func:`pennylane.classical_shadow` for detailed documentation.
 
 
     Args:

pennylane/measurements/counts.py

@@ -161,7 +161,7 @@ class CountsMP(SampleMeasurement):
     """Measurement process that samples from the supplied observable and returns the number of
     counts for each sample.
 
-    Please refer to :func:`counts` for detailed documentation.
+    Please refer to :func:`pennylane.counts` for detailed documentation.
 
     Args:
         obs (Union[.Operator, .MeasurementValue]): The observable that is to be measured

pennylane/measurements/expval.py

@@ -77,7 +77,7 @@ def circuit(x):
 class ExpectationMP(SampleMeasurement, StateMeasurement):
     """Measurement process that computes the expectation value of the supplied observable.
 
-    Please refer to :func:`expval` for detailed documentation.
+    Please refer to :func:`pennylane.expval` for detailed documentation.
 
     Args:
         obs (Union[.Operator, .MeasurementValue]): The observable that is to be measured

pennylane/measurements/mid_measure.py

@@ -234,7 +234,7 @@ class MidMeasureMP(MeasurementProcess):
     This class additionally stores information about unknown measurement outcomes in the qubit model.
     Measurements on a single qubit in the computational basis are assumed.
 
-    Please refer to :func:`measure` for detailed documentation.
+    Please refer to :func:`pennylane.measure` for detailed documentation.
 
     Args:
         wires (.Wires): The wires the measurement process applies to.

pennylane/measurements/mutual_info.py

@@ -91,7 +91,7 @@ def circuit_mutual(x):
 class MutualInfoMP(StateMeasurement):
     """Measurement process that computes the mutual information between the provided wires.
 
-    Please refer to :func:`mutual_info` for detailed documentation.
+    Please refer to :func:`pennylane.mutual_info` for detailed documentation.
 
     Args:
         wires (Sequence[.Wires]): The wires the measurement process applies to.

pennylane/measurements/probs.py

@@ -136,7 +136,7 @@ def circuit():
 class ProbabilityMP(SampleMeasurement, StateMeasurement):
     """Measurement process that computes the probability of each computational basis state.
 
-    Please refer to :func:`probs` for detailed documentation.
+    Please refer to :func:`pennylane.probs` for detailed documentation.
 
     Args:
         obs (Union[.Operator, .MeasurementValue]): The observable that is to be measured

pennylane/measurements/purity.py

@@ -66,7 +66,7 @@ def circuit_purity(p):
 class PurityMP(StateMeasurement):
     """Measurement process that computes the purity of the system prior to measurement.
 
-    Please refer to :func:`purity` for detailed documentation.
+    Please refer to :func:`pennylane.purity` for detailed documentation.
 
     Args:
         wires (.Wires): The wires the measurement process applies to.

pennylane/measurements/sample.py

@@ -141,7 +141,7 @@ class SampleMP(SampleMeasurement):
     """Measurement process that returns the samples of a given observable. If no observable is
     provided then basis state samples are returned directly from the device.
 
-    Please refer to :func:`sample` for detailed documentation.
+    Please refer to :func:`pennylane.sample` for detailed documentation.
 
     Args:
         obs (Union[.Operator, .MeasurementValue]): The observable that is to be measured

pennylane/measurements/state.py

@@ -129,7 +129,7 @@ def circuit():
 class StateMP(StateMeasurement):
     """Measurement process that returns the quantum state in the computational basis.
 
-    Please refer to :func:`state` for detailed documentation.
+    Please refer to :func:`pennylane.state` for detailed documentation.
 
     Args:
         wires (.Wires): The wires the measurement process applies to.

pennylane/measurements/var.py

@@ -69,7 +69,7 @@ def circuit(x):
 class VarianceMP(SampleMeasurement, StateMeasurement):
     """Measurement process that computes the variance of the supplied observable.
 
-    Please refer to :func:`var` for detailed documentation.
+    Please refer to :func:`pennylane.var` for detailed documentation.
 
     Args:
         obs (Union[.Operator, .MeasurementValue]): The observable that is to be measured