Title
Optimal Estimation of Low Rank Density Matrices
Abstract
The density matrices are positively semi-definite Hermitian matrices of unit trace that describe the state of a quantum system. The goal of the paper is to develop minimax lower bounds on error rates of estimation of low rank density matrices in trace regression models used in quantum state tomography (in particular, in the case of Pauli measurements) with explicit dependence of the bounds on the rank and other complexity parameters. Such bounds are established for several statistically relevant distances, including quantum versions of Kullback-Leibler divergence (relative entropy distance) and of Hellinger distance (so called Bures distance), and Schatten p-norm distances. Sharp upper bounds and oracle inequalities for least squares estimator with von Neumann entropy penalization are obtained showing that minimax lower bounds are attained (up to logarithmic factors) for these distances.
Year
DOI
Venue
2015
10.5555/2789272.2886806
JOURNAL OF MACHINE LEARNING RESEARCH
Keywords
Field
DocType
quantum state tomography,low rank density matrix,minimax lower bounds
Discrete mathematics,Mathematical optimization,Minimax,Hellinger distance,Matrix (mathematics),Quantum tomography,Trace distance,Von Neumann entropy,Hermitian matrix,Mathematics,Kullback–Leibler divergence
Journal
Volume
Issue
ISSN
16
1
1532-4435
Citations 
PageRank 
References 
3
0.42
6
Authors
2
Name
Order
Citations
PageRank
Vladimir Koltchinskii1899.61
Dong Xia2286.31