A continuous-time diffusion limit theorem for dynamical decoupling and intrinsic decoherence

Authors Organisations
Type Article
Original languageEnglish
Article number155301
Number of pages27
JournalJournal of Physics A: Mathematical and Theoretical
Volume48
Issue number15
DOI
Publication statusPublished - 17 Apr 2015
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Abstract

We discuss a few mathematical aspects of random dynamical decoupling, a key tool procedure in quantum information theory. In particular, we place it in the context of discrete stochastic processes, limit theorems and completely positive trace-preserving semigroups on matrix algebras. We obtain precise analytical expressions for expectation and variance of the density matrix and fidelity over time in the continuum-time limit depending on the system Lindbladian, which then lead to rough short-time estimates depending only on certain coupling strengths. We prove that dynamical decoupling does not work in the case of intrinsic (i.e., not environment-induced) decoherence, and together with the above-mentioned estimates this yields a novel method of partially identifying intrinsic decoherence.

Keywords

  • central limit theorem, CPT semigroups, dynamical decoupling, intrinsic decoherence