States tomography of quantum systems via twisted light

Tomography of quantum state is an experimental procedure for determination of an unknown density operator ρ (the so called density matrix) which characterizes this state. In the case of single-qubit quantum system it is necessary to define the 12 parameters. While for the two-qubit system we should be assessed 240 parameters. Nevertheless, there are experimental techniques that allow to make a state's tomography. When the unitary evolution takes place we can use the von Neumann equation in formalism of quantum transformations, and when the non-unitary evolution takes place we can use the so-called Lindblad equation. Using a Gaussian beam (or twisted light) gives additional possibilities for realization of a quantum state's tomography procedure for different systems.