dorsal/arxiv
View SchemaProjection Postulate and Atomic Quantum Zeno Effect
| Authors | Almut Beige, Gerhard C. Hegerfeldt |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/9512012 |
| URL | https://arxiv.org/abs/quant-ph/9512012 |
| DOI | 10.1103/PhysRevA.53.53 |
| Journal | Phys.Rev.A53:53-65,1996 |
Abstract
The projection postulate has been used to predict a slow-down of the time evolution of the state of a system under rapidly repeated measurements, and ultimately a freezing of the state. To test this so-called quantum Zeno effect an experiment was performed by Itano et al. (Phys. Rev. A 41, 2295 (1990)) in which an atomic-level measurement was realized by means of a short laser pulse. The relevance of the results has given rise to controversies in the literature. In particular the projection postulate and its applicability in this experiment have been cast into doubt. In this paper we show analytically that for a wide range of parameters such a short laser pulse acts as an effective level measurement to which the usual projection postulate applies with high accuracy. The corrections to the ideal reductions and their accumulation over n pulses are calculated. Our conclusion is that the projection postulate is an excellent pragmatic tool for a quick and simple understanding of the slow-down of time evolution in experiments of this type. However, corrections have to be included, and an actual freezing does not seem possible because of the finite duration of measurements.
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"abstract": "The projection postulate has been used to predict a slow-down of the time\nevolution of the state of a system under rapidly repeated measurements, and\nultimately a freezing of the state. To test this so-called quantum Zeno effect\nan experiment was performed by Itano et al. (Phys. Rev. A 41, 2295 (1990)) in\nwhich an atomic-level measurement was realized by means of a short laser pulse.\nThe relevance of the results has given rise to controversies in the literature.\nIn particular the projection postulate and its applicability in this experiment\nhave been cast into doubt. In this paper we show analytically that for a wide\nrange of parameters such a short laser pulse acts as an effective level\nmeasurement to which the usual projection postulate applies with high accuracy.\nThe corrections to the ideal reductions and their accumulation over n pulses\nare calculated. Our conclusion is that the projection postulate is an excellent\npragmatic tool for a quick and simple understanding of the slow-down of time\nevolution in experiments of this type. However, corrections have to be\nincluded, and an actual freezing does not seem possible because of the finite\nduration of measurements.",
"arxiv_id": "quant-ph/9512012",
"authors": [
"Almut Beige",
"Gerhard C. Hegerfeldt"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.53.53",
"journal_ref": "Phys.Rev.A53:53-65,1996",
"title": "Projection Postulate and Atomic Quantum Zeno Effect",
"url": "https://arxiv.org/abs/quant-ph/9512012"
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