Efficient tomography of quantum processes

Xiang-Bin Wang, J. -Z. Hu, Z. -W. Yu, Franco Nori

Published 2010-10-04Version 1

We show with explicit formulas that one can completely identify an unknown quantum process with only one weakly entangled state; and identify a quantum optical Gaussian process with either one two-mode squeezed state or a few different coherent states. In tomography of a multi-mode process, our method reduces the number of different test states exponentially compared with existing methods.