Abstract

We consider the problem of quantum-state tomography under the assumption that the state is pure, and more generally that its rank is bounded by a given value . In this scenario two notions of informationally complete measurements emerge: rank--complete measurements and rank- strictly-complete measurements. Whereas in the first notion, a rank- state is uniquely identified from within the set of rank- states, in the second notion the same state is uniquely identified from within the set of all physical states, of any rank. We argue, therefore, that strictly-complete measurements are compatible with convex optimization, and we prove that they allow robust quantum-state estimation in the presence of experimental noise. We also show that rank- strictly-complete measurements are as efficient as rank--complete measurements. We construct examples of strictly-complete measurements and give a complete …

Date

May 6, 2016

Authors

Charles H Baldwin, Ivan H Deutsch, Amir Kalev

Journal

Physical Review A

Volume

93

Issue

5

Pages

052105

Publisher

American Physical Society