:py:mod:`kosmos.quantum_logic.quantum_state`
============================================

.. py:module:: kosmos.quantum_logic.quantum_state







Classes
-------

.. py:class:: QuantumState(*, creation_time: int | None = 0, rho: numpy.ndarray | None = None, fidelity: float | None = 0.0)


   Representation of a quantum state using a density matrix.

   Initialize and validate density matrix and validity of state.

   :param creation_time: Timestamp of creation. Defaults to 0.
   :type creation_time: int | None
   :param rho: Density matrix of a quantum register. Defaults to None.
   :type rho: np.ndarray | None
   :param fidelity: Fidelity value of a quantum register. Defaults to 0.0.
   :type fidelity: float | None




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   .. rubric:: Properties

   .. py:property:: rho

      Density matrix of a state.

   .. py:property:: dim

      Dimension of rho.



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   .. rubric:: Methods

   .. py:method:: validate_density_matrix(rho: numpy.ndarray, tolerance: float = 1e-10) -> None

      Verify whether the density matrix represents a quantum state.

      :param rho: Density matrix.
      :type rho: np.ndarray
      :param tolerance: Tolerance due to inaccurate calculations. Defaults to 1e-10.
      :type tolerance: float


   .. py:method:: fidelity_from_rho(target: QuantumState) -> float

      Compute Uhlmann fidelity between two states.

      :param target: target quantum state.
      :type target: QuantumState

      :returns: Fidelity value between 0 and 1.
      :rtype: float


   .. py:method:: fidelity_with_target(target_rho: numpy.ndarray) -> float

      Compute fidelity between this state and an ideal target state.

      How close is the actual state to the ideal state.

      :param target_rho: Density matrix of the ideal target state.
      :type target_rho: np.ndarray

      :returns: Fidelity value between 0 and 1:
      :rtype: float