2010/07/31 by Fernando Galve, Gian Luca Giorgi, Roberta Zambrini · 97 citations
Computer Science · Mathematics · Physics and Astronomy · #Hilbert space #Mathematical analysis #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum correlation #Quantum discord #Quantum entanglement #Quantum mechanics #Quantum state #Qubit #Separable space #Separable state #Statistical physics #Statistics #Value (mathematics) #quant-ph
paper · pdf · doi:10.1103/physreva.83.012102
published in Physical Review A 83(1) (American Physical Society)
openalex publication_date 2011/01/13 · arxiv created 2011/01/14 · arxiv updated 2011/01/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the relative strength of classical and quantum correlations, as measured by discord, for two-qubit states. Quantum correlations appear only in the presence of classical correlations, while the reverse is not always true. We identify the family of states that maximize the discord for a given value of the classical correlations and show that the largest attainable discord for mixed states is greater than for pure states. The difference between discord and entanglement is emphasized by the remarkable fact that these states do not maximize entanglement and are, in some cases, even separable. Finally, by random generation of density matrices uniformly distributed over the whole Hilbert space, we quantify the frequency of the appearance of quantum and classical correlations for different ranks.