release notes

releasenotes/notes/optimize-annotated-conjugate-reduction-656438d3642f27dc.yaml

@@ -0,0 +1,17 @@
+features:
+  - |
+    Added a new reduction to the :class:`.OptimizeAnnotated` transpiler pass.
+    This reduction looks for annotated operations (objects of type :class:`.AnnotatedOperation`
+    that consist of a base operation ``B`` and a list ``M`` of control, inverse and power
+    modifiers) with the following properties:
+
+    * the base operation needs to be synthesized (i.e. it's not already supported
+      by the target or belongs to the equivalence library)
+
+    * the definition circuit for``B`` can be expressed as ``P -- Q -- R`` with :math:`R = P^{-1}`
+
+    In this case the modifiers can moved to the ``Q``-part only. As a specific example, controlled
+    QFT-based adders have the form ``control - [QFT -- U -- IQFT]``, which can be simplified to
+    ``QFT -- control-[U] -- IQFT. By removing the controls over ``QFT`` and ``IQFT`` parts of the
+    circuit, one obtains significantly fewer gates in the transpiled circuit.
+