---
features:
  - |
    Added a new keyword argument, ``abelian_grouping``, to
    the :class:`~.Estimator`. This argument is used to control whether the
    :class:`~.Estimator` will group the input observables into qubit-wise
    commutable observables which reduces the number of circuit executions
    required to compute the expectation value and improves the runtime
    performance of the :class:`~.Estimator`. By default this is set to
    ``True``.
upgrade:
  - |
    The default behavior of the :class:`~.Estimator` primitive will now
    group the input observable into qubit-wise commutable observables.
    The grouping reduces the number of circuits to be executed and improves
    the performance. If you desire the previous behavior you can initialize
    your :class:`~.Estimator` instance with the keyword argument
    ``abelian_grouping=False``.
