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 tracepreserving semigroups on matrix algebras. We obtain precise analytical expressions for expectation and variance of the density matrix and fidelity over time in the continuumtime limit depending on the system Lindbladian, which then lead to rough shorttime estimates depending only on certain coupling strengths. We prove that dynamical decoupling does not work in the case of intrinsic (i.e., not environmentinduced) decoherence, and together with the abovementioned estimates this yields a novel method of partially identifying intrinsic decoherence.
Original language  English 

Article number  155301 
Pages (fromto)  127 
Number of pages  27 
Journal  Journal of Physics A: Mathematical and Theoretical 
Volume  48 
Issue number  15 
DOIs  
Publication status  Published  25 Mar 2015 
Keywords
 central limit theorem
 CPT semigroups
 dynamical decoupling
 intrinsic decoherence
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Daniel Burgarth
 Faculty of Business and Physical Sciences, Department of Mathematics  Honorary Appointmenten
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