Strong NP-Hardness of the Quantum Separability Problem
Abstract
Given the density matrix rho of a bipartite quantum state, the quantum separability problem asks whether rho is entangled or separable. In 2003, Gurvits showed that this problem is NP-hard if rho is located within an inverse exponential (with respect to dimension) distance from the border of the set of separable quantum states. In this paper, we extend this NP-hardness to an inverse polynomial distance from the separable set. The result follows from a simple combination of works by Gurvits, Ioannou, and Liu. We apply our result to show (1) an immediate lower bound on the maximum distance between a bound entangled state and the separable set (assuming P != NP), and (2) NP-hardness for the problem of determining whether a completely positive trace-preserving linear map is entanglement-breaking.
Cite
@article{arxiv.0810.4507,
title = {Strong NP-Hardness of the Quantum Separability Problem},
author = {Sevag Gharibian},
journal= {arXiv preprint arXiv:0810.4507},
year = {2010}
}
Comments
18 pages, 1 figure. v5: Updated version to appear in Quantum Information & Computation. Includes additional details in proof of NP-hardness of determining whether a quantum channel is entanglement-breaking, as well as minor updates to improve readability throughout. Thank you to anonymous referees for their comments