qiskit/visualization/utils.py
def _validate_input_state(quantum_state):
    """Validates the input to state visualization functions.

    Args:
        quantum_state (ndarray): Input state / density matrix.
    Returns:
        rho: A 2d numpy array for the density matrix.
    Raises:
        VisualizationError: Invalid input.
    """
    rho = np.asarray(quantum_state)
    if rho.ndim == 1:
        rho = np.outer(rho, np.conj(rho))
    # Check the shape of the input is a square matrix
    shape = np.shape(rho)
    if len(shape) != 2 or shape[0] != shape[1]:
        raise VisualizationError("Input is not a valid quantum state.")
    # Check state is an n-qubit state
    num = int(np.log2(rho.shape[0]))
    if 2 ** num != rho.shape[0]:
        raise VisualizationError("Input is not a multi-qubit quantum state.")
    return rho
def _validate_input_state(quantum_state):
    """Validates the input to state visualization functions.

    Args:
        quantum_state (ndarray): Input state / density matrix.
    Returns:
        rho: A 2d numpy array for the density matrix.
    Raises:
        VisualizationError: Invalid input.
    """
    rho = np.asarray(quantum_state)
    if rho.ndim == 1:
        rho = np.outer(rho, np.conj(rho))
    # Check the shape of the input is a square matrix
    shape = np.shape(rho)
    if len(shape) != 2 or shape[0] != shape[1]:
        raise VisualizationError("Input is not a valid quantum state.")
    # Check state is an n-qubit state
    num = int(np.log2(rho.shape[0]))
    if 2 ** num != rho.shape[0]:
        raise VisualizationError("Input is not a multi-qubit quantum state.")
    return rho
Validates the input to state visualization functions.

    Args:
        quantum_state (ndarray): Input state / density matrix.
    Returns:
        rho: A 2d numpy array for the density matrix.
    Raises:
        VisualizationError: Invalid input.