2011/12/31 by Sania Jevtic, David Jennings, Terry Rudolph · 1 citation
Computer Science · Mathematics · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Algorithm #Bipartite graph #Discrete mathematics #Mathematics #Physics #Quantum #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum information #Quantum mechanics #Quantum state #Quantum system #State (computer science) #Statistical physics #Unitary state #quant-ph
paper · pdf · doi:10.1103/physreva.85.052121
published as Phys. Rev. A 85, 052121 (2012) · 23 pages, 10 figures
openalex publication_date 2012/05/23 · arxiv created 2012/05/31 · arxiv updated 2012/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Motivated by thermodynamic considerations, we analyze the variation of the quantum mutual information on a unitary orbit of a bipartite system's state with and without global constraints such as energy conservation. We solve the full optimization problem for the smallest system of two qubits and explore thoroughly the effect of unitary operations on the space of reduced-state spectra. We then provide applications of these ideas to physical processes within closed quantum systems such as a generalized collision model approach to thermal equilibrium and a global Maxwell demon playing tricks on local observers. For higher dimensions, the maximization of correlations is relatively straightforward for equal-sized subsystems, however their minimization displays nontrivial structures. We characterize a set of separable states in which the minimally correlated state resides: a collection of classically correlated states admitting a particular ``Young tableau'' form. Furthermore, a partial order exists on this set with respect to individual marginal entropies, and the presence of a ``see-saw effect'' for these entropies forces a finer analysis to determine the optimal tableau.