Abstract.
We present a theory to establish a relation between Hahn spin-echo of a spin-1/2 particle and quantum phase transitions in many-body systems. The Hahn echo is calculated and discussed at zero as well as at finite temperatures. On the example of XY model, we show that the critical points of the chain are marked by the extremal values in the Hahn echo, and can influence the Hahn echo in finite temperatures. An explanation for the relation between the echo and criticality is also presented.
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For any initial state of the spin-chain, vE(τ)=1 for γ=0. This can be found in equation ([SEE TEXT])
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Yi, X., Wang, H. & Wang, W. Hahn echo and criticality in spin-chain systems. Eur. Phys. J. D 45, 355–362 (2007). https://doi.org/10.1140/epjd/e2007-00266-6
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DOI: https://doi.org/10.1140/epjd/e2007-00266-6