2012/02/14 by Liqun Qi, Qi, Liqun · 2 citations
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum Physics (quant-ph) #quant-ph
paper · pdf · doi:10.48550/arxiv.1202.2983
arxiv created 2012/02/14 · openalex publication_date 2012/02/14 · arxiv updated 2012/02/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A general n-partite state | Ψ> of a composite quantum system can be regarded as an element in a Hilbert tensor product space \HH = ⊗k=1n \HHk, where the dimension of \HHk is dk for k = 1,..., n. Without loss of generality we may assume that d1 ≤...≤ dn. A separable (Hartree) n-partite state | ϕ> can be described by | ϕ> = ⊗k=1n | ϕ(k)> with | ϕ(k)> ∈ \HHk. We show that σ:= min \< Ψ| ϕΨ> : | Ψ> ∈ \HH,. . < Ψ| Ψ> = 1\ is a positive number, where | ϕΨ> is the nearest separable state to | Ψ>. We call σ the minimum Hartree value of \HH. We further show that σ≥ 1/√d1... dn-1. Thus, the geometric measure of the entanglement content of Ψ, ‖ | Ψ> - | ϕΨ> ‖ ≤ √(2-2σ) ≤ √2-2(1/√d1...dn-1).