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.
|Number of pages||27|
|Journal||Journal of Physics A: Mathematical and Theoretical|
|Publication status||Published - 25 Mar 2015|
- central limit theorem
- CPT semigroups
- dynamical decoupling
- intrinsic decoherence
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- Faculty of Business and Physcial Sciences, Department of Mathematics - Honorary Appointment