Update release notes

releasenotes/notes/remove-deadweight-5d68e3fa42fc19bd.yaml

@@ -2,19 +2,62 @@
 features_transpiler:
   - |
     The scheduling passes :class:`.PadDelay` and :class:`.PadDynamicalDecoupling` has new arguments on
-    their constructors ``target`` and ``durations``.
+    their constructors ``target`` and ``durations`` these are used to specify the :class:`.Target` or
+    :class:`.InstructionDurations` respectively. This is required to provide the durations for the
+    instructions in the circuit when this pass is run.
 upgrade_circuits:
   - |
-    The deprecated attributes for :class:`.Instruction` and :class:`.Gate`: ``duration`` and ``unit``.
-
+    The deprecated attributes for :class:`.Instruction` and :class:`.Gate`: ``duration`` and ``unit``. This includes
+    setting the ``unit`` or ``duration`` arguments for any :class:`qiskit.circuit.Instruction`
+    or subclass. These attributes were deprecated in Qiskit 1.3.0. These attributes were used to attach a custom execution
+    duration and unit for that duration to an individual instruction. However,
+    the source of truth of the duration of a gate is the :class:`.BackendV2`
+    :class:`.Target` which contains the duration for each instruction supported
+    on the backend. The duration of an instruction is not something that's
+    typically user adjustable and is an immutable property of the backend. If
+    you were previously using this capability to experiment with different
+    durations for gates you can mutate the
+    :attr:`.InstructionProperties.duration` field in a given :class:`.Target` to
+    set a custom duration for an instruction on a backend (the unit is always in
+    seconds in the :class:`.Target`).
   - |
     The deprecated attribute for :class:`.Instruction` and :class:`.Gate`: ``condition`` has been
-    removed
+    removed. These attributes were deprecated in the 1.3.0 release.
+    This functionality has been superseded by the :class:`.IfElseOp` class
+    which can be used to describe a classical condition in a circuit.
   - |
     The deprecated methods for :class:`.Instruction` and :class:`.Gate`: ``c_if`` and ``condition_bits``
-    have been removed.
+    have been removed. These methods were deprecated in the 1.3.0 release.
+    This functionality has been superseded by the :class:`.IfElseOp` class
+    which can be used to describe a classical condition in a circuit.
+    For example, a circuit using  :meth:`.Instruction.c_if` like::
+
+        from qiskit.circuit import QuantumCircuit
+
+        qc = QuantumCircuit(2, 2)
+        qc.h(0)
+        qc.x(0).c_if(0, 1)
+        qc.z(1.c_if(1, 0)
+        qc.measure(0, 0)
+        qc.measure(1, 1)
+
+    can be rewritten as::
+
+        qc = QuantumCircuit(2, 2)
+        qc.h(0)
+        with expected.if_test((expected.clbits[0], True)):
+            qc.x(0)
+        with expected.if_test((expected.clbits[1], False)):
+            qc.z(1)
+        qc.measure(0, 0)
+        qc.measure(1, 1)
+
   - |
-    The deprecated methods ``InstructionSet.c_if`` has been removed.
+    The deprecated methods ``InstructionSet.c_if`` has been removed. This method
+    was deprecated in the 1.3.0 release. This functionality has been superseded
+    by the :class:`.IfElseOp` class which can be used to describe a classical
+    condition in a circuit.
+
 upgrade_transpiler:
   - |
     The :class:`.ResetAfterMeasureSimplification` transpiler pass now will use an :class:`.IfElseOp`
@@ -38,12 +81,17 @@ upgrade_transpiler:
     removed. These arguments were deprecated in Qiskit 1.4.0 and were removed because the larger
     removal of ``Instruction.condition`` it no longer served a purpose.
   - |
-    The previously deprecated ``AlignMeasures`` transpiler pass has been removed.
+    The previously deprecated ``AlignMeasures`` transpiler pass has been removed. This pass was deprecated in Qiskit 1.1.0. Instead the
+    :class:`.ConstrainedReschedule` pass should be used. :class:`.ConstrainedReschedule` performs the
+    same function and also supports aligning to additional timing constraints.
   - |
     When calling :func:`.generate_preset_pass_manager` or :func:`.transpile` and specifying the ``instruction_durations`` argument
     with a list instead of an :class:`.InstructionDurations` object and the list specifies durations in units of ``dt`` a ``dt`` parameter
     is required if scheduling the circuit.
 
 upgrade_visualization:
   - |
-    The timeline drawer now requires the target argument is specified when called. This was deprecated in 1.4.0.
+    The timeline drawer now requires the target argument is specified when called. As instructions no
+    longer contain duration attributes this extra argument is required to
+    specify the durations for all the supported instructions. Without the
+    argument the timeline drawer does not have access to this information.