:py:mod:`states.max_mixed`
==========================

.. py:module:: states.max_mixed

.. autoapi-nested-parse::

   Maximally mixed state.



Module Contents
---------------


Functions
~~~~~~~~~

.. autoapisummary::

   states.max_mixed.max_mixed



.. py:function:: max_mixed(dim, is_sparse = False)

   Produce the maximally mixed state :cite:`Aaronson_2018_MaxMixed`.

   Produces the maximally mixed state on of :code:`dim` dimensions. The maximally mixed state is defined as

   .. math::
       \omega = \frac{1}{d} \begin{pmatrix}
                       1 & 0 & \ldots & 0 \\
                       0 & 1 & \ldots & 0 \\
                       \vdots & \vdots & \ddots & \vdots \\
                       0 & 0 & \ldots & 1
                   \end{pmatrix},

   or equivalently, it is defined as

   .. math::
       \omega = \frac{\mathbb{I}}{\text{dim}(\mathcal{X})}

   for some complex Euclidean space :math:`\mathcal{X}`. The maximally mixed state is sometimes also referred to as the
   tracial state.

   The maximally mixed state is returned as a sparse matrix if :code:`is_sparse = True` and is full if :code:`is_sparse
   = False`.

   .. rubric:: Examples

   Using :code:`toqito`, we can generate the :math:`2`-dimensional maximally mixed state

   .. math::
       \omega_2 = \frac{1}{2}
       \begin{pmatrix}
           1 & 0 \\
           0 & 1
       \end{pmatrix}

   as follows.

   >>> from toqito.states import max_mixed
   >>> max_mixed(2, is_sparse=False)
   array([[0.5, 0. ],
          [0. , 0.5]])

   One may also generate a maximally mixed state returned as a sparse matrix

   >>> from toqito.states import max_mixed
   >>> max_mixed(2, is_sparse=True) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
   <2x2 sparse array of type '<class 'numpy.float64'>'
       with 2 stored elements in Compressed Sparse Row format>

   .. rubric:: References

   .. bibliography::
       :filter: docname in docnames

   :param dim: Dimension of the entangled state.
   :param is_sparse: `True` if vector is sparse and `False` otherwise.
   :return: The maximally mixed state of dimension `dim`.