dorsal/arxiv
View SchemaQuantum Zeno effect by general measurements
| Authors | K. Koshino, A. Shimizu |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0411145 |
| URL | https://arxiv.org/abs/quant-ph/0411145 |
| DOI | 10.1016/j.physrep.2005.03.001 |
| Journal | Phys.Rept. 412 (2005) 191-275 |
Abstract
It was predicted that frequently repeated measurements on an unstable quantum state may alter the decay rate of the state. This is called the quantum Zeno effect (QZE) or the anti-Zeno effect (AZE), depending on whether the decay is suppressed or enhanced. In conventional theories of the QZE and AZE, effects of measurements are simply described by the projection postulate, assuming that each measurement is an instantaneous and ideal one. However, real measurements are not instantaneous and ideal. For the QZE and AZE by such general measurements, interesting and surprising features have recently been revealed, which we review in this article. The results are based on the quantum measurement theory, which is also reviewed briefly. As a typical model, we consider a continuous measurement of the decay of an excited atom by a photodetector that detects a photon emitted from the atom upon decay. This measurement is an indirect negative-result one, for which the curiosity of the QZE and AZE is emphasized. It is shown that the form factor is renormalized as a backaction of the measurement, through which the decay dynamics is modified. In a special case of the flat response, where the detector responds to every photon mode with an identical response time, results of the conventional theories are reproduced qualitatively. However, drastic differences emerge in general cases where the detector responds only to limited photon modes. For example, against predictions of the conventional theories, the QZE or AZE may take place even for states that exactly follow the exponential decay law. We also discuss relation to the cavity quantum electrodynamics.
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"abstract": "It was predicted that frequently repeated measurements on an unstable quantum\nstate may alter the decay rate of the state. This is called the quantum Zeno\neffect (QZE) or the anti-Zeno effect (AZE), depending on whether the decay is\nsuppressed or enhanced. In conventional theories of the QZE and AZE, effects of\nmeasurements are simply described by the projection postulate, assuming that\neach measurement is an instantaneous and ideal one. However, real measurements\nare not instantaneous and ideal. For the QZE and AZE by such general\nmeasurements, interesting and surprising features have recently been revealed,\nwhich we review in this article. The results are based on the quantum\nmeasurement theory, which is also reviewed briefly. As a typical model, we\nconsider a continuous measurement of the decay of an excited atom by a\nphotodetector that detects a photon emitted from the atom upon decay. This\nmeasurement is an indirect negative-result one, for which the curiosity of the\nQZE and AZE is emphasized. It is shown that the form factor is renormalized as\na backaction of the measurement, through which the decay dynamics is modified.\nIn a special case of the flat response, where the detector responds to every\nphoton mode with an identical response time, results of the conventional\ntheories are reproduced qualitatively. However, drastic differences emerge in\ngeneral cases where the detector responds only to limited photon modes. For\nexample, against predictions of the conventional theories, the QZE or AZE may\ntake place even for states that exactly follow the exponential decay law. We\nalso discuss relation to the cavity quantum electrodynamics.",
"arxiv_id": "quant-ph/0411145",
"authors": [
"K. Koshino",
"A. Shimizu"
],
"categories": [
"quant-ph",
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"physics.atom-ph"
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"doi": "10.1016/j.physrep.2005.03.001",
"journal_ref": "Phys.Rept. 412 (2005) 191-275",
"title": "Quantum Zeno effect by general measurements",
"url": "https://arxiv.org/abs/quant-ph/0411145"
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