Experimental quantum state tomography via compressed sampling.
A fundamental difficulty in demonstrating quantum state tomography is that the required resources grow exponentially with the system size. For pure states and nearly pure states, the task of tomography can be more efficient. We proposed two methods for state reconstruction, by (1) minimizing entropy and (2) maximizing likelihood. The algorithm of compressed sampling is employed to solve the optimization problem. Experiments are demonstrated considering 4-qubit photonic states. The results show that (1) much fewer measurements than the standard tomography are sufficient to obtain high fidelity, and (2) the method of maximizing likelihood is more accurate and noise robust than the original reconstruction method of compressed sampling. Furthermore, the physical meaning of the methods of minimizing entropy and maximizing likelihood is clear.
Department of Physics, College of Science, National University of Defense Technology, Changsha, People's Republic of China. wtliu@nudt.edu.cn
Wei-Tao
WT
Liu
Ting
T
Zhang
Ji-Ying
JY
Liu
Ping-Xing
PX
Chen
Jian-Min
JM
Yuan