Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Delayed Choice Experiments and the Bohm Approach.

Basil J. Hiley, R. E. Callaghan

Published Jan 1, 2006• 36 citations
OpenAlex

Abstract

The delayed choice experiments of the type introduced by Wheeler and extended by Englert, Scully, Süssmann and Walther [ESSW], and others, have formed a rich area for investigating the puzzling behaviour of particles undergoing quantum interference. The surprise provided by the original delayed choice experiment, led Wheeler to the conclu-sion that “no phenomenon is a phenomenon until it is an observed phenomenon”, a radical explanation which implied that “the past has no existence except as it is recorded in the present”. However Bohm, Dewdney and Hiley have shown that the Bohm interpretation gives a straightforward account of the behaviour of the particle without re-sorting to such a radical explanation. The subsequent modifications of this experiment led both Aharonov and Vaidman and [ESSW] to conclude that the resulting Bohm-type trajectories in these new sit-uations produce unacceptable properties. For example, if a cavity is

Related papers

Delayed-choice experiments and the Bohm approach

Basil J. Hiley, R E Callaghan

The delayed-choice experiments of the type introduced by Wheeler and extended by Englert, Scully, Süssmann and Walther (ESSW) (1992 Z. Naturf. a 47 1175–86), and others, have formed a rich area for investigating the puzzling behaviour of particles undergoing quantum interference. The surprise provided by the original delayed-choice experiment led Wheeler to the conclusion that 'no phenomenon is a phenomenon until it is an observed phenomenon', a radical explanation which implied that 'the past has no existence except as it is recorded in the present'. However Bohm et al (1985 Nature 315 294–97) have shown that the Bohm interpretation (BI) gives a straightforward account of the behaviour of the particle without resorting to such a radical explanation. The subsequent modifications of this experiment led both Aharonov and Vaidman (1996 Bohmian Mechanics and Quantum Theory: An Appraisal ed J T Cushing, A Fine and S Goldstein (Dordrecht: Kluwer) pp 141–54) and ESSW to conclude that the resulting Bohm-type trajectories in these new situations produce unacceptable properties. For example, if a cavity is placed in one arm of the interferometer, it will be excited by a particle travelling down the other arm. In other words, it is the particle that does not go through the cavity that gives up its energy! If this analysis is correct, this behaviour would be truly bizarre and could only be explained by an extreme non-local transfer of energy that is even stronger than that required in an Einstein, Podolsky and Rosen (EPR)-type process. In this paper, we show that this conclusion is not correct and that if the BI is used correctly, it gives a local explanation, which actually corresponds exactly to the standard quantum mechanics explanation offered by ESSW.

arXiv:1602.06100•Physica Scripta•Aug 9, 2006•29 citations

Restoration of interference and the fallacy of delayed choice: Concerning an experiment proposed by Englert, Scully, and Walther

Ulrich Mohrhoff

A two-slit experiment with atoms, proposed by Englert, Scully, and Walther, appears to permit experimenters to choose, after each atom has made its mark on the screen, whether the atom has passed through a particular slit or has, in some sense, passed through both of them. Through a misleading wording these authors even appear to endorse this interpretation. In actual fact, this choice exists only until the atom hits the screen. The said experiment thus is a ‘‘delayed-choice’’ experiment only in the semantically contingent sense of Wheeler.

American Journal of Physics•Dec 1, 1996•34 citations

Taming the Delayed Choice Quantum Eraser

Johannes Fankhauser

I discuss the delayed choice quantum eraser experiment by drawing an analogy to a Bell-type measurement and giving a straightforward account in standard quantum mechanics. The delayed choice quantum eraser experiment turns out to resemble a Bell-type scenario in which the resolution of the paradox is rather trivial, and so there really is no mystery. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of backwards in time influence. I argue that this issue can be eliminated by taking into proper account the role of the signal photon. Likewise, in the de Broglie–Bohm picture the trajectories of the particle can be given a well-defined description at any instant of time during the experiment. Thus, it is again clear that there is no need to resort to any kind of backwards in time influence. Quanta 2019; 8: 44-56.

arXiv:1707.07884•Quanta•Aug 11, 2019•10 citations

Discussion on the speed of interference: Transient phenomena in delayed-choice experiments

Masanori Sato

Signaling by a delayed-choice experimental setup was discussed in the previous report [M. Sato, quant-ph/0409059]. In this report, the speed of the interference pattern generation in Wheeler's delayed-choice experiment is discussed, and a feasible experimental proposal is provided. The duality of locality and nonlocality obviously appears in the de Broglie-Bohm picture. Locality corresponds to the particle property and nonlocality corresponds to the wave property. The interference of a photon can be recognized using the de Broglie-Bohm picture. A photon moves at the speed of light, however the speed of the interference pattern formation, which is conducted by a quantum potential, is not seen to be restricted by the speed of light.

•Jul 31, 2006•0 citations

The Enigma of Delayed Choice Quantum Eraser

Tabish Qureshi

The delayed-choice quantum eraser represents an interesting experiment that exemplifies Bohr's principle of complementarity in a beautiful way. According to the complementarity principle, in a two-path interference experiment, the knowledge of which path was taken by the particle and the appearance of interference are mutually exclusive. Even when the which-path information is merely retained in specific quantum path-markers, without being actually read, it suffices to eliminate interference. Nevertheless, if this path information is erased in some manner, the interference re-emerges, a phenomenon referred to as the quantum eraser. An intriguing aspect of this experiment is that if the path information is erased after the particle has been detected on the screen, the interference still reappears, a phenomenon known as the delayed-choice quantum eraser. This observation has led to the interpretation that the particle can be influenced to exhibit characteristics of either a particle or a wave based on a decision made long after it has been registered on the screen. This idea has sparked considerable debate and discussions surrounding retrocausality. This controversy is reviewed here, and a detailed resolution provided. Quanta 2025; 14: 66–74.

arXiv:2510.23539•Quanta•Nov 23, 2025•1 citation

Bohr's double-slit experiment - once again!

Erik Rüdinger

In recent years there has been an upsurge in the discussion of so-called delayed-choice experiments, as exemplified in the interferometer experiment discussed by Wheeler [1]. In commenting on this experiment Bohm et al. [2] claim that their quantum potential interpretation gives results entirely compatible with Bohr's views on wholeness and complementarity. It seems to me, however, that this discussion to a large extent completely misses the fundamental point in Bohr's argumentation as given in his famour answer [3] to Einstein, Podolsky and Rosen as well as in his paper on his discussions with Einstein [4]. Expressing it a bit paradoxically one might say that in the examples discussed the experiments are not sufficiently delayed. I shall therefore here discuss a different thought experiment, much closer to Bohr's own examples, which brings out this point.

Physica Scripta•May 1, 1989•0 citations
The delayed choice experiments of the type introduced by Wheeler and extended by Englert, Scully, Süssmann and Walther [ESSW], and others, have formed a rich area for investigating the puzzling behaviour of particles undergoing quantum interference. The surprise provided by the original delayed choice experiment, led Wheeler to the conclu-sion that “no phenomenon is a phenomenon until it is an observed phenomenon”, a radical explanation which implied that “the past has no existence except as it is recorded in the present”. However Bohm, Dewdney and Hiley have shown that the Bohm interpretation gives a straightforward account of the behaviour of the particle without re-sorting to such a radical explanation. The subsequent modifications of this experiment led both Aharonov and Vaidman and [ESSW] to conclude that the resulting Bohm-type trajectories in these new sit-uations produce unacceptable properties. For example, if a cavity is
The delayed-choice experiments of the type introduced by Wheeler and extended by Englert, Scully, Süssmann and Walther (ESSW) (1992 Z. Naturf. a 47 1175–86), and others, have formed a rich area for investigating the puzzling behaviour of particles undergoing quantum interference. The surprise provided by the original delayed-choice experiment led Wheeler to the conclusion that 'no phenomenon is a phenomenon until it is an observed phenomenon', a radical explanation which implied that 'the past has no existence except as it is recorded in the present'. However Bohm et al (1985 Nature 315 294–97) have shown that the Bohm interpretation (BI) gives a straightforward account of the behaviour of the particle without resorting to such a radical explanation. The subsequent modifications of this experiment led both Aharonov and Vaidman (1996 Bohmian Mechanics and Quantum Theory: An Appraisal ed J T Cushing, A Fine and S Goldstein (Dordrecht: Kluwer) pp 141–54) and ESSW to conclude that the resulting Bohm-type trajectories in these new situations produce unacceptable properties. For example, if a cavity is placed in one arm of the interferometer, it will be excited by a particle travelling down the other arm. In other words, it is the particle that does not go through the cavity that gives up its energy! If this analysis is correct, this behaviour would be truly bizarre and could only be explained by an extreme non-local transfer of energy that is even stronger than that required in an Einstein, Podolsky and Rosen (EPR)-type process. In this paper, we show that this conclusion is not correct and that if the BI is used correctly, it gives a local explanation, which actually corresponds exactly to the standard quantum mechanics explanation offered by ESSW.
A two-slit experiment with atoms, proposed by Englert, Scully, and Walther, appears to permit experimenters to choose, after each atom has made its mark on the screen, whether the atom has passed through a particular slit or has, in some sense, passed through both of them. Through a misleading wording these authors even appear to endorse this interpretation. In actual fact, this choice exists only until the atom hits the screen. The said experiment thus is a ‘‘delayed-choice’’ experiment only in the semantically contingent sense of Wheeler.
I discuss the delayed choice quantum eraser experiment by drawing an analogy to a Bell-type measurement and giving a straightforward account in standard quantum mechanics. The delayed choice quantum eraser experiment turns out to resemble a Bell-type scenario in which the resolution of the paradox is rather trivial, and so there really is no mystery. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of backwards in time influence. I argue that this issue can be eliminated by taking into proper account the role of the signal photon. Likewise, in the de Broglie–Bohm picture the trajectories of the particle can be given a well-defined description at any instant of time during the experiment. Thus, it is again clear that there is no need to resort to any kind of backwards in time influence. Quanta 2019; 8: 44-56.
Signaling by a delayed-choice experimental setup was discussed in the previous report [M. Sato, quant-ph/0409059]. In this report, the speed of the interference pattern generation in Wheeler's delayed-choice experiment is discussed, and a feasible experimental proposal is provided. The duality of locality and nonlocality obviously appears in the de Broglie-Bohm picture. Locality corresponds to the particle property and nonlocality corresponds to the wave property. The interference of a photon can be recognized using the de Broglie-Bohm picture. A photon moves at the speed of light, however the speed of the interference pattern formation, which is conducted by a quantum potential, is not seen to be restricted by the speed of light.
The delayed-choice quantum eraser represents an interesting experiment that exemplifies Bohr's principle of complementarity in a beautiful way. According to the complementarity principle, in a two-path interference experiment, the knowledge of which path was taken by the particle and the appearance of interference are mutually exclusive. Even when the which-path information is merely retained in specific quantum path-markers, without being actually read, it suffices to eliminate interference. Nevertheless, if this path information is erased in some manner, the interference re-emerges, a phenomenon referred to as the quantum eraser. An intriguing aspect of this experiment is that if the path information is erased after the particle has been detected on the screen, the interference still reappears, a phenomenon known as the delayed-choice quantum eraser. This observation has led to the interpretation that the particle can be influenced to exhibit characteristics of either a particle or a wave based on a decision made long after it has been registered on the screen. This idea has sparked considerable debate and discussions surrounding retrocausality. This controversy is reviewed here, and a detailed resolution provided. Quanta 2025; 14: 66–74.
In recent years there has been an upsurge in the discussion of so-called delayed-choice experiments, as exemplified in the interferometer experiment discussed by Wheeler [1]. In commenting on this experiment Bohm et al. [2] claim that their quantum potential interpretation gives results entirely compatible with Bohr's views on wholeness and complementarity. It seems to me, however, that this discussion to a large extent completely misses the fundamental point in Bohr's argumentation as given in his famour answer [3] to Einstein, Podolsky and Rosen as well as in his paper on his discussions with Einstein [4]. Expressing it a bit paradoxically one might say that in the examples discussed the experiments are not sufficiently delayed. I shall therefore here discuss a different thought experiment, much closer to Bohr's own examples, which brings out this point.