Commutation dag (#1712)

* remove newlines in docstring (#1647) * First version. * Working version. * DAG successors. * Update documentation and code quality. * Black * More black * Protected access. * Import order. * Target_wires to tar_wires. * Typo. * Typo. * More black. * Add observable attribute and tests. * Black. * More black. * Add more tests. * Add more tests. * Sort pred succ * Add support SWAP. * More coverage. * Black. * Update from review. * Black. * Update pennylane/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Changes from review. * Random codefactor * Remove some changes. * Black. * Change target qpe, qmc * More doc. * Update param gates * Param Ops * Update parameters * More ops * Add templates. * Update * More tests. * More tests. * Update from refractor. * Update * black * Update. * Update. * Better integration with future control update * Black. * Typo * Adapt for pattern matching. * Update coverage * More coverage * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update from review. * Test simplify * Test simplify * Remove * Simplify docstring * Update doc/releases/changelog-dev.md Co-authored-by: Josh Izaac <josh146@gmail.com> * Update doc/releases/changelog-dev.md Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * black * Update from review * Update doc/releases/changelog-dev.md * Update doc/releases/changelog-dev.md Co-authored-by: Josh Izaac <josh146@gmail.com> * Update doc/releases/changelog-dev.md Co-authored-by: Josh Izaac <josh146@gmail.com> * Update pennylane/transforms/commutation_dag.py Co-authored-by: Josh Izaac <josh146@gmail.com> * More * Doc Co-authored-by: Theodor <theodor@xanadu.ai> Co-authored-by: Josh Izaac <josh146@gmail.com>
PennyLaneAI · Mar 1, 2022 · 5a6c2f5 · 5a6c2f5
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diff --git a/doc/releases/changelog-dev.md b/doc/releases/changelog-dev.md
@@ -4,6 +4,53 @@
 
 <h3>New features since last release</h3>
 
+* Transform a circuit from quantum tape, quantum function or quantum node to a pairwise
+  commutation DAG (directed acyclic graph). The node represents the quantum operations, and the edges represent 
+  non commutation between two operations.
+  [(#1712)](https://github.com/PennyLaneAI/pennylane/pull/1712)
+
+  From the following quantum function,
+  ```
+  def circuit(x, y, z):
+      qml.RX(x, wires=0)
+      qml.RX(y, wires=0)
+      qml.CNOT(wires=[1, 2])
+      qml.RY(y, wires=1)
+      qml.Hadamard(wires=2)
+      qml.CRZ(z, wires=[2, 0])
+      qml.RY(-y, wires=1)
+      return qml.expval(qml.PauliZ(0))
+  ```
+  the commutation DAG can be returned by using the following code:
+  ```
+  get_dag = commutation_dag(circuit)
+  theta = np.pi/4
+  phi = np.pi/3
+  psi = np.pi/2
+  dag = get_dag(theta, phi, psi)
+  ```
+  You can access all nodes by using the ``get_nodes`` function in the form of a list ``(ID, CommutationDAGNode)``:
+  ```
+  nodes = dag.get_nodes()
+  [(0, <pennylane.transforms.commutation_dag.CommutationDAGNode object at 0x132b03b20>), ...]
+  ```
+
+  You can also access specific nodes ``CommutationDAGNode`` by using the ``get_node`` function. From the ``CommutationDAGNode``
+  you can directly access all node attributes.
+
+  ```
+  >>> second_node = dag.get_node(2)
+  <pennylane.transforms.commutation_dag.CommutationDAGNode object at 0x136f8c4c0>
+  
+  >>> second_operation = second_node.op
+  CNOT(wires=[1, 2])
+  
+  >>> second_node_successors = second_node.successors
+  [3, 4, 5, 6]
+  
+  >>> second_node_predecessors = second_node.predecessors
+  []
+  ```
 * The text based drawer accessed via `qml.draw` has been overhauled.
   [(#2128)](https://github.com/PennyLaneAI/pennylane/pull/2128)
   [(#2198)](https://github.com/PennyLaneAI/pennylane/pull/2198)
@@ -317,6 +364,6 @@ The Operator class has undergone a major refactor with the following changes:
 This release contains contributions from (in alphabetical order):
 
 Thomas Bromley, Anthony Hayes, Josh Izaac, Christina Lee,
-Maria Fernanda Morris, Zeyue Niu, Maria Schuld, Jay Soni, Antal Száva,
-David Wierichs
+Maria Fernanda Morris, Romain Moyard, Zeyue Niu, Maria Schuld, Jay Soni,
+Antal Száva, David Wierichs
 
diff --git a/pennylane/__init__.py b/pennylane/__init__.py
@@ -69,6 +69,9 @@
     single_tape_transform,
     quantum_monte_carlo,
     apply_controlled_Q,
+    commutation_dag,
+    is_commuting,
+    simplify,
 )
 from pennylane.optimize import *
 from pennylane.vqe import ExpvalCost, VQECost

diff --git a/pennylane/operation.py b/pennylane/operation.py
@@ -1184,6 +1184,7 @@ def grad_method(self):
         s_1]=[-1/2, 1, -\pi/2]` is assumed for every parameter.
     """
 
+    # Attributes for compilation transforms
     basis = None
     """str or None: The target operation for controlled gates.
     target operation. If not ``None``, should take a value of ``"X"``, ``"Y"``,

diff --git a/pennylane/templates/subroutines/qpe.py b/pennylane/templates/subroutines/qpe.py
@@ -108,6 +108,7 @@ def circuit():
     grad_method = None
 
     def __init__(self, unitary, target_wires, estimation_wires, do_queue=True, id=None):
+
         target_wires = list(target_wires)
         estimation_wires = list(estimation_wires)
         wires = target_wires + estimation_wires

diff --git a/pennylane/transforms/__init__.py b/pennylane/transforms/__init__.py
@@ -81,6 +81,16 @@
     ~transforms.zyz_decomposition
     ~transforms.two_qubit_decomposition
     ~transforms.set_decomposition
+    ~transforms.simplify
+
+There are also utility functions that take a circuit and return a DAG.
+
+.. autosummary::
+    :toctree: api
+
+    ~transforms.commutation_dag
+    ~transforms.CommutationDAG
+    ~transforms.CommutationDAGNode
 
 Transforms for circuit cutting
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -170,6 +180,13 @@
 from .qmc import apply_controlled_Q, quantum_monte_carlo
 from .unitary_to_rot import unitary_to_rot
 from .get_unitary_matrix import get_unitary_matrix
+from .commutation_dag import (
+    commutation_dag,
+    is_commuting,
+    CommutationDAG,
+    CommutationDAGNode,
+    simplify,
+)
 from .tape_expand import (
     expand_invalid_trainable,
     expand_multipar,