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Quantum Zeno effect — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/Quantum_Zeno_effect
License (as archived): CC-BY-SA-4.0
Archived: 2026-10-07T12:32:59.826Z
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Quantum Zeno effect — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/Quantum_Zeno_effect (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_2f2739733117 (Metraipolis archive dc_2f2739733117, sha256 2db3491923b3d1c114c78f9aed39ade314e403bb8d43ecfdcdf4cc5eb0f52c04)

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@misc{dc2f2739733117,
  title = {Quantum Zeno effect — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/Quantum_Zeno_effect},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_2f2739733117; sha256 2db3491923b3d1c114c78f9aed39ade314e403bb8d43ecfdcdf4cc5eb0f52c04},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/Quantum_Zeno_effect. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

In quantum mechanics, frequent measurements cause the quantum Zeno effect, a reduction in transitions away from the system's initial state, slowing a system's time evolution. Sometimes this effect is interpreted as "a system cannot change while you are watching it". One can "freeze" the evolution of the system by measuring it frequently enough in its known initial state. The meaning of the term has since expanded, leading to a more technical definition, in which time evolution can be suppressed not only by measurement: the quantum Zeno effect is the suppression of unitary time evolution in quantum systems provided by a variety of sources: measurement, interactions with the environment, stochastic fields, among other factors. As an outgrowth of study of the quantum Zeno effect, it has become clear that applying a series of sufficiently strong and fast pulses with appropriate symmetry can also decouple a system from its decohering environment. The name comes by analogy to Zeno's arrow paradox, which states that because an arrow in flight is not seen to move during any single instant, it cannot possibly be moving at all. In the quantum Zeno effect an unstable state seems frozen – to not 'move' – due to a constant series of observations. The comparison is due to a 1977 article by Baidyanath Misra and E. C. George Sudarshan. According to the reduction postulate, each measurement causes the wavefunction to collapse to an eigenstate of the measurement basis. In the context of this effect, an observation can simply be the absorption of a particle, without the need of an observer in any conventional sense. However, there is controversy over the interpretation of the effect, sometimes referred to as the "measurement problem" in traversing the interface between microscopic and macroscopic objects. Another crucial problem related to the effect is strictly connected to the time–energy indeterminacy relation (part of the indeterminacy principle). If one wants to make the measurement process more and more frequent, one has to correspondingly decrease the time duration of the measurement itself. But the request that the measurement last only a very short time implies that the energy spread of the state in which reduction occurs becomes increasingly large. However, the deviations from the exponential decay law for small times is crucially related to the inverse of the energy spread, so that the region in which the deviations are appreciable shrinks when one makes the measurement process duration shorter and shorter. An explicit evaluation of these two competing requests shows that it is inappropriate, without taking into account this basic fact, to deal with the actual occurrence and emergence of Zeno's effect. Closely related (and sometimes not distinguished from the quantum Zeno effect) is the watchdog effect, in which the time evolution of a system is affected by its continuous coupling to the environment.

Tema degli esploratori: fisica e astronomia (deposito sistematico; ricerca «quantum mechanics»).
Fonte: Wikipedia in inglese, voce «Quantum Zeno effect» — https://en.wikipedia.org/wiki/Quantum_Zeno_effect
Wikidata Q1897309: «effect in quantum mechanics which disallows certain conditions in the decaying of a quantum state» (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q1897309
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/Quantum_Zeno_effect?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1375363140, consultata il 2026-10-07T12:05:34.086Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: f2f0bfaa28fb6f6abb871687bcb10513c376cf6ebd2239de75e7d29a375990d8