Decoherence and pointer states in small antiferromagnets: A benchmark test

Abstract

We study the decoherence process of a four spin-1/2 antiferromagnet that is coupled to an environment of spin-1/2 particles. The preferred basis of the antiferromagnet is discussed in two limiting cases and we identify two $exact$ pointer states. Decoherence near the two limits is examined whereby entropy is used to quantify the $robustness$ of states against environmental coupling. We find that close to the quantum measurement limit, the self-Hamiltonian of the system of interest can become dynamically relevant on macroscopic timescales. We illustrate this point by explicitly constructing a state that is more robust than (generic) states diagonal in the system-environment interaction Hamiltonian.

21 pages

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• Suppressing backscattering of helical edge modes with a spin bath
• Pointer States in the Born-Markov approximation