TY - JOUR T1 - Quantum state tomography via reduced density matrices JF - Physical Review Letters Y1 - 2017 A1 - Tao Xin A1 - Dawei Lu A1 - Joel Klassen A1 - Nengkun Yu A1 - Zhengfeng Ji A1 - Jianxin Chen A1 - Xian Ma A1 - Guilu Long A1 - Bei Zeng A1 - Raymond Laflamme AB -

Quantum state tomography via local measurements is an efficient tool for characterizing quantum states. However it requires that the original global state be uniquely determined (UD) by its local reduced density matrices (RDMs). In this work we demonstrate for the first time a class of states that are UD by their RDMs under the assumption that the global state is pure, but fail to be UD in the absence of that assumption. This discovery allows us to classify quantum states according to their UD properties, with the requirement that each class be treated distinctly in the practice of simplifying quantum state tomography. Additionally we experimentally test the feasibility and stability of performing quantum state tomography via the measurement of local RDMs for each class. These theoretical and experimental results advance the project of performing efficient and accurate quantum state tomography in practice.

VL - 118 U4 - 020401 UR - http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.020401 U5 - 10.1103/PhysRevLett.118.020401 ER -