dorsal/arxiv
View SchemaGaussian Decoherence and Gaussian Echo from Spin Environments
| Authors | W. H. Zurek, F. M. Cucchietti, J. P. Paz |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0611200 |
| URL | https://arxiv.org/abs/quant-ph/0611200 |
| Journal | Acta Physica Polonica B, 38, No. 5 (2007), 1685 |
Abstract
We examine an exactly solvable model of decoherence -- a spin-system interacting with a collection of environment spins. We show that in this simple model (introduced some time ago to illustrate environment--induced superselection) generic assumptions about the coupling strengths lead to a universal (Gaussian) suppression of coherence between pointer states. We explore the regime of validity of this result and discuss its relation to spectral features of the environment. We also consider its relevance to the experiments on the so-called Loschmidt echo (which measures, in effect, the fidelity between the initial and time-reversed or "echo" signal). In particular, we show that for partial reversals (e.g., when of only a part of the total Hamiltonian changes sign) fidelity will exhibit a Gaussian dependence on the time of reversal. In such cases echo may become independent of the details of the reversal procedure or the specifics of the coupling to the environment. This puzzling behavior was observed in several NMR experiments. Natural candidates for such two environments (one of which is easily reversed, while the other is ``irreversible'') are suggested for the experiment involving ferrocene.
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"abstract": "We examine an exactly solvable model of decoherence -- a spin-system\ninteracting with a collection of environment spins. We show that in this simple\nmodel (introduced some time ago to illustrate environment--induced\nsuperselection) generic assumptions about the coupling strengths lead to a\nuniversal (Gaussian) suppression of coherence between pointer states. We\nexplore the regime of validity of this result and discuss its relation to\nspectral features of the environment. We also consider its relevance to the\nexperiments on the so-called Loschmidt echo (which measures, in effect, the\nfidelity between the initial and time-reversed or \"echo\" signal). In\nparticular, we show that for partial reversals (e.g., when of only a part of\nthe total Hamiltonian changes sign) fidelity will exhibit a Gaussian dependence\non the time of reversal. In such cases echo may become independent of the\ndetails of the reversal procedure or the specifics of the coupling to the\nenvironment. This puzzling behavior was observed in several NMR experiments.\nNatural candidates for such two environments (one of which is easily reversed,\nwhile the other is ``irreversible\u0027\u0027) are suggested for the experiment involving\nferrocene.",
"arxiv_id": "quant-ph/0611200",
"authors": [
"W. H. Zurek",
"F. M. Cucchietti",
"J. P. Paz"
],
"categories": [
"quant-ph",
"cond-mat.other"
],
"journal_ref": "Acta Physica Polonica B, 38, No. 5 (2007), 1685",
"title": "Gaussian Decoherence and Gaussian Echo from Spin Environments",
"url": "https://arxiv.org/abs/quant-ph/0611200"
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