Remove qml.broadcast template (#6527)

Context:

Completing the deprecation cycle of `qml.broadcast`.

Description of the Change:

1. Update deprecations.rst
2. Update changelog-dev.md
3. Remove all deprecated source code

Found references in Catalyst:
PennyLaneAI/catalyst#1290
No references found in Lightning and QML.

[sc-77484]

---------

Co-authored-by: Mudit Pandey <[email protected]>

doc/development/deprecations.rst

@@ -20,11 +20,6 @@ Pending deprecations
   - Deprecated in v0.39
   - Will be removed in v0.40
 
-* ``qml.broadcast`` has been deprecated. Users should use ``for`` loops instead.
-
-  - Deprecated in v0.39
-  - Will be removed in v0.40
-
 * The ``qml.qinfo`` module has been deprecated. Please see the respective functions in the ``qml.math`` and ``qml.measurements``
   modules instead.
 
@@ -111,6 +106,11 @@ Other deprecations
 Completed deprecation cycles
 ----------------------------
 
+* ``qml.broadcast`` has been removed. Users should use ``for`` loops instead.
+
+  - Deprecated in v0.39
+  - Removed in v0.40
+
 * The ``max_expansion`` argument for :func:`~pennylane.transforms.decompositions.clifford_t_decomposition`
   has been removed.
 

doc/introduction/templates.rst

@@ -360,54 +360,6 @@ Other useful templates which do not belong to the previous categories can be fou
 
 .. _intro_ref_temp_constr:
 
-Broadcasting function
----------------------
-
-PennyLane offers a broadcasting function to easily construct templates: :func:`~.broadcast`
-takes either quantum gates or templates and applies them to wires in a specific pattern.
-
-.. warning::
-
-    While the broadcasting function can make template construction very convenient, it
-    adds an overhead and is therefore not recommended when speed is a major concern.
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Single) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_single.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Double) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_double.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Double Odd) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_double_odd.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Chain) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_chain.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Ring) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_ring.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Pyramid) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_pyramid.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (All-to-All) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_alltoall.png
-
-.. gallery-item::
-    :description: :doc:`Broadcast (Custom) <../code/api/pennylane.broadcast>`
-    :figure: _static/templates/broadcast_custom.png
-
-.. raw:: html
-
-        <div style='clear:both'></div>
-
-.. _intro_ref_temp_init:
 
 Parameter initializations
 -------------------------

doc/releases/changelog-dev.md

@@ -71,6 +71,9 @@
 
 <h3>Breaking changes 💔</h3>
 
+* `qml.broadcast` has been removed. Users should use `for` loops instead.
+  [(#6527)](https://github.com/PennyLaneAI/pennylane/pull/6527)
+
 * The `max_expansion` argument for `qml.transforms.clifford_t_decomposition` has been removed.
   [(#6531)](https://github.com/PennyLaneAI/pennylane/pull/6531)
 

pennylane/__init__.py

@@ -74,7 +74,7 @@
 )
 from pennylane.ops import *
 from pennylane.ops import adjoint, ctrl, cond, exp, sum, pow, prod, s_prod
-from pennylane.templates import broadcast, layer
+from pennylane.templates import layer
 from pennylane.templates.embeddings import *
 from pennylane.templates.layers import *
 from pennylane.templates.tensornetworks import *

pennylane/templates/__init__.py

@@ -15,7 +15,6 @@
 This module contains templates, which are pre-coded routines that can be used in a quantum node.
 """
 
-from .broadcast import *
 from .embeddings import *
 from .layer import *
 from .layers import *