Experimental demonstration of efficient quantum state tomography of matrix product states

Quantum state tomography is a key technology for fully determining a quantum state. Unfortunately, standard quantum state tomography is intractable for general many-body quantum states, because the number of measurements and the post-processing time increase exponentially with the size of the system. However, for the matrix product states (MPSs), there exists an efficient method using linearly scaled local measurements and polynomially scaled post-processing times. In this study, we demonstrate the validity of the method in practice by reconstructing a four-photon MPS from its local two-or three-photon reduced-density matrices with the presence of statistical errors and systematical errors in experiment. (C) 2017 Optical Society of America