---
features:
  - |
    ``AerState`` has a new method ``initialize_density_matrix()`` that sets a density matrix
    to ``AER::QV::DensityMatrix``. This method will be called in ``q.i.states.DensityMatrix``
    to initialize its data with ``ndarray``. ``initialize_density_matrix()`` has a boolean
    argument that specifies copy or share of ``ndarray`` data. If the data is shared with
    C++ and python, the data must not be collected in python while C++ accesses it.
