qiskit/releasenotes/notes/0.23/new_pulse_subclass-44da7746...

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---
features:
- |
Introduced a new subclass :class:`~qiskit.pulse.library.ScalableSymbolicPulse`, as a
sub class of :class:`~qiskit.pulse.library.SymbolicPulse`. The new subclass behaves
the same as :class:`~qiskit.pulse.library.SymbolicPulse`,
except that it assumes that the envelope of the pulse includes a complex amplitude
pre-factor of the form `amp * exp(1j * angle)`.
This envelope shape matches many common pulses, including all of the pulses in
the Qiskit Pulse library (which were also converted to 'amp','angle' representation in
this release).
The new subclass removes the non-unique nature of the `amp`,`angle` representation,
and correctly compares pulses according to their complex amplitude.
upgrade:
- |
The QPY version format version emitted by :func:.qpy.dump has been
increased to version 6. This new format version is incompatible with the
previous versions and will result in an error when trying to load it with
a deserializer that isn't able to handle QPY version 6. This change was
necessary to support the introduction of :class:`~qiskit.pulse.library.ScalableSymbolicPulse`
which was handled by adding a `class_name_size` attribute to the header
of dumped :class:`~qiskit.pulse.library.SymbolicPulse` objects.
- |
The hashing option for :class:`~qiskit.pulse.library.SymbolicPulse` was removed
to better reflect their mutable nature (via parameter assignment).