A Conceptual Analysis of Quantum Zeno; Paradox, Measurement, and Experiment

Home, Dipankar; Whitaker, M. A. B.

doi:10.1006/aphy.1997.5699

Cited by 183 publications

(159 citation statements)

References 96 publications

(153 reference statements)

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“…As pointed out by Home and Whitaker "there should be a desire to understand more about the collapse postulate, why it often works well, its limitations, and how it should be eventually adapted or replaced." [6]. In this context a natural question is: is it possible to conceive processes leading to detectable differences associated to the reduction of the wave function with different time scales?…”

Section: Introductionmentioning

confidence: 99%

Estimating the reduction time of quantum states

Parisio

2011

Phys. Rev. A

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An effective description of microscopic measurements is given, in which the precise moment of probing is not determined. Within this scenario we propose a scheme that relies on an "attempt" to make a forbidden simultaneous measurement of two incompatible observables. Although bound to failure in what concerns this goal, the process can lead to experimentally accessible information on a possibly non-vanishing time δt elapsed in the collapsing of the wave function, even if the duration ∆t of the individual measurements is much larger than δt.

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Section: Introductionmentioning

confidence: 99%

Estimating the reduction time of quantum states

Parisio

2011

Phys. Rev. A

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“…Experimental demonstrations of the QZE [2,3,4,5,6,7,8] have been driven by interest in both fundamental physics and practical applications. Practical applications of the QZE include reducing decoherence in quantum computing [8,9,10], efficient preservation of spin polarized gases [3,4,6], and dosage reduction in neutron tomography [11].The QZE is a paradigm and test bed for quantum measurement theory [12,13]. In one interpretation, it involves many sequential collapses of the wavefunctions of the system.…”

mentioning

confidence: 99%

Continuous and Pulsed Quantum Zeno Effect

Streed¹,

Mun²,

Boyd³

et al. 2006

Phys. Rev. Lett.

178

186

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Continuous and pulsed quantum Zeno effects were observed using a 87 Rb Bose-Einstein condensate (BEC). Oscillations between two ground hyperfine states of a magnetically trapped condensate, externally driven at a transition rate ωR, were suppressed by destructively measuring the population in one of the states with resonant light. The suppression of the transition rate in the two level system was quantified for pulsed measurements with a time interval δt between pulses and continuous measurements with a scattering rate γ. We observe that the continuous measurements exhibit the same suppression in the transition rate as the pulsed measurements when γδt = 3.60(0.43), in agreement with the predicted value of 4. Increasing the measurement rate suppressed the transition rate down to 0.005ωR.PACS numbers: 03.65. Xp,03.75.Mn,42.50.Xa The quantum Zeno effect (QZE) is the suppression of transitions between quantum states by frequent measurements. It was first considered as a theoretical problem where the continuous observation of an unstable particle would prevent its decay [1]. Experimental demonstrations of the QZE [2,3,4,5,6,7,8] have been driven by interest in both fundamental physics and practical applications. Practical applications of the QZE include reducing decoherence in quantum computing [8,9,10], efficient preservation of spin polarized gases [3,4,6], and dosage reduction in neutron tomography [11].The QZE is a paradigm and test bed for quantum measurement theory [12,13]. In one interpretation, it involves many sequential collapses of the wavefunctions of the system. Quantum Zeno experiments provide constraints for speculative extensions of quantum mechanics where the collapse of the wavefunction is created by extra terms in a modified Schrödinger equation [14]. It is still an open question how close one can approach the limit of an infinite number of interrogations due to the Heisenberg uncertainty involved in shorter measurement times. These conceptional questions provide the motivation to extend experimental tests of the quantum Zeno phenonmenon. A major improvement to a quatum Zeno experiment with ultracold neutrons [15] is in preparation.In this letter we compare the suppression of the transition rate in an oscillating two level system by continuous and pulsed measurements. Our QZE experiments were carried out with Bose-Einstein condensed atoms [16,17,18]. The long coherence time and the high degree of control of the position and momentum of the atoms created a very clean system and allowed us to observe much stronger quantum Zeno suppression than before [2,5,7]. In the experiment with pulsed measurements up to 500 measurements could be carried out and survival probabilities exceeded 98%. Furthermore, we have performed the first quantitative comparison between the pulsed and continuous measurement QZE. This is important since any real pulsed measurement is only an approximation based on a series of weak continuous measurements [19,20].Let us consider a two-level system which is externally driven at a ...

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“…The only way to analyse continuous measurements via the Postulate would be to treat them as the limiting case of increasingly frequent projective measurements. But the quantum Zeno effect ( [11]; see [10] for discussion) tells us that the result of any such limiting-case measurement is to freeze the system's evolution altogether, in flat contradiction of what we actually observe in continuous measurements. (This was the original reason that Misra and Sudarshan, who did analyse continuous measurement in exactly this way, called the quantum Zeno effect a 'paradox'.…”

Section: The Myth Of the 'Conventional Interpretation'mentioning

confidence: 82%

Decoherence and its role in the modern measurement problem

Wallace

2012

Phil. Trans. R. Soc. A.

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Decoherence is widely felt to have something to do with the quantum measurement problem, but getting clear on just what is made difficult by the fact that the 'measurement problem', as traditionally presented in foundational and philosophical discussions, has become somewhat disconnected from the conceptual problems posed by real physics. This, in turn, is because quantum mechanics as discussed in textbooks and in foundational discussions has become somewhat removed from scientific practice, especially where the analysis of measurement is concerned. This paper has two goals: firstly ( § §1-2), to present an account of how quantum measurements are actually dealt with in modern physics (hint: it does not involve a collapse of the wave function) and to state the measurement problem from the perspective of that account; and secondly ( § §3-4), to clarify what role decoherence plays in modern measurement theory and what effect it has on the various strategies that have been proposed to solve the measurement problem.

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A Conceptual Analysis of Quantum Zeno; Paradox, Measurement, and Experiment

Cited by 183 publications

References 96 publications

Estimating the reduction time of quantum states

Estimating the reduction time of quantum states

Continuous and Pulsed Quantum Zeno Effect

Decoherence and its role in the modern measurement problem

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