Quantum tomography of the optical four level states

摘要

We discuss a procedure of measurement of an arbitrary quantum state of an optical system in Hilbert space with the dimension d = 4. Such states can be realized using a collinear frequency-nondegenerate regime of spontaneous parametric down-conversion. The method has been tested for a number of polarization states of a biphoton field. A high accuracy of the reconstruction of the states (above 99%) indicates that the procedures proposed for reconstructing the quantum state of the system are adequate.