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

arXiv:quant-ph/0701109 · Journal of Quantum Information Science

Modified Two-Slit Experiments and Complementarity

Tabish Qureshi

Published Jan 1, 2012• 9 citations
arXivHTMLPDF

Abstract

Some modified two-slit interference experiments claim to demonstrate a violation of Bohr’s complementarity principle. A typical such experiment is theoretically analyzed using wave-packet dynamics. The flaw in the analysis of such experiments is pointed out and it is demonstrated that they do not violate complementarity. In addition, it is quite generally proved that if the state of a particle is such that the modulus square of the wave-function yields an interference pattern, then it necessarily loses which-path information.

DOI
10.4236/jqis.2012.22007

Related papers

Complementarity and the Afshar Experiment

Tabish Qureshi

A modified two-slit interference experiment, proposed and carried out by Shahriar Afshar [first reported by M. Chown, New Scientist {\\bf 183}, 30 (2004)], claims to demonstrate a violation of Bohr's complementarity principle. We point out the flaw in Afshar's analysis and show why complementarity is robust and cannot be violated in any experiment which is a variant of the conventional two-slit experiment.

•Jan 16, 2007•6 citations

Complementarity in the double-slit experiment: Quantum nonseparability and a quantitative statement of Bohr's principle

William K. Wootters, Wojciech Hubert Zurek

A detailed analysis of Einstein's version of the double-slit experiment, in which one tries to observe both wave and particle properties of light, is performed. Quantum nonseparability appears in the derivation of the interference pattern, which proves to be surprisingly sharp even when the trajectories of the photons have been determined with fairly high accuracy. An information-theoretic approach to this problem leads to a quantitative formulation of Bohr's complementarity principle for the case of the double-slit experiment. A practically realizable version of this experiment, to which the above analysis applies, is proposed.

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields•Jan 15, 1979•617 citations

On delayed choice and quantum erasure in two-slit experiment for testing complementarity

Guang-Liang Li

The principle of complementarity is one of the cornerstones of quantum theory. The aim of this study was to advance our understanding of complementarity by analyzing the role of delayed choice and quantum erasers in two-slit experiments, and by proposing experiments for verifying the analysis. The analysis is based on models consisting of measurable spaces and probability measures involved in the experiments. The main findings are as follows: (a) The complementarity principle manifests itself in such a way that wave and particle behaviors cannot be simultaneously observed almost surely with respect to any single, fixed measure. (b) Described by different measures, complementary properties can coexist in the same experimental setup. (c) Which-way information will not preclude or erase interference fringes. (d) Delayed choice and quantum erasers are irrelevant to testing complementarity. (e) It is possible for us to know through which slit each quantum object passed almost surely with respect to the measure corresponding to the slit while the interference pattern is intact. Based on the experiments analyzed, realizable experiments are proposed for verifying the above results.

Journal of Physics Communications•Sep 13, 2021•3 citations

No Paradox in Wave–Particle Duality

Andrew Knight

The assertion that an experiment by Afshar et al. demonstrates violation of Bohr’s Principle of Complementarity is based on the faulty assumption that which-way information in a double-slit interference experiment can be retroactively determined from a future measurement.

•Jan 1, 2020•3 citations

The Reality of de Broglie’s Pilot Wave

António Cardoso

In this paper we discuss a recent double-slit experiment where which-path information is obtained without disturbing the photons in their path to the detector, and, as a consequence, an interference pattern is observed on the far screen even if it is known which slit the photons go through. We argue that this result is in clear contradiction with a fundamental principle in orthodox quantum mechanics – Bohr’s complementarity principle – and also point out that, on the other hand, the results of this experiment are the expected ones in the framework of de Broglie’s pilot wave theory

•Aug 1, 2015•0 citations

Should We Interpret Quantum Mechanics According to Bohr

Shubhayan Sarkar

I present here a thought experiment which violates the most widely accepted interpretation of quantum mechanics “The Copenhagen Interpretation” and Bohr’s complementarity which says that there is no meaning of the state of a particle until it is observed and the act of observation might change it. The experiment consists of a double slit apparatus which is modified by putting a second double slit apparatus between the source and the original apparatus with certain conditions imposed on both the apparatuses using the facts of interference and diffraction. A striking paradox emerges if we consider the arguments of Bohr’s complementarity, i.e. the photon travels through both the paths simultaneously in a double slit apparatus whenever there is interference. It turns out that this paradox can be resolved only if the photon travels through one path even if interference fringes are visible.

•Mar 1, 2017•0 citations
Some modified two-slit interference experiments claim to demonstrate a violation of Bohr’s complementarity principle. A typical such experiment is theoretically analyzed using wave-packet dynamics. The flaw in the analysis of such experiments is pointed out and it is demonstrated that they do not violate complementarity. In addition, it is quite generally proved that if the state of a particle is such that the modulus square of the wave-function yields an interference pattern, then it necessarily loses which-path information.
A detailed analysis of Einstein's version of the double-slit experiment, in which one tries to observe both wave and particle properties of light, is performed. Quantum nonseparability appears in the derivation of the interference pattern, which proves to be surprisingly sharp even when the trajectories of the photons have been determined with fairly high accuracy. An information-theoretic approach to this problem leads to a quantitative formulation of Bohr's complementarity principle for the case of the double-slit experiment. A practically realizable version of this experiment, to which the above analysis applies, is proposed.
The principle of complementarity is one of the cornerstones of quantum theory. The aim of this study was to advance our understanding of complementarity by analyzing the role of delayed choice and quantum erasers in two-slit experiments, and by proposing experiments for verifying the analysis. The analysis is based on models consisting of measurable spaces and probability measures involved in the experiments. The main findings are as follows: (a) The complementarity principle manifests itself in such a way that wave and particle behaviors cannot be simultaneously observed almost surely with respect to any single, fixed measure. (b) Described by different measures, complementary properties can coexist in the same experimental setup. (c) Which-way information will not preclude or erase interference fringes. (d) Delayed choice and quantum erasers are irrelevant to testing complementarity. (e) It is possible for us to know through which slit each quantum object passed almost surely with respect to the measure corresponding to the slit while the interference pattern is intact. Based on the experiments analyzed, realizable experiments are proposed for verifying the above results.
In this paper we discuss a recent double-slit experiment where which-path information is obtained without disturbing the photons in their path to the detector, and, as a consequence, an interference pattern is observed on the far screen even if it is known which slit the photons go through. We argue that this result is in clear contradiction with a fundamental principle in orthodox quantum mechanics – Bohr’s complementarity principle – and also point out that, on the other hand, the results of this experiment are the expected ones in the framework of de Broglie’s pilot wave theory
I present here a thought experiment which violates the most widely accepted interpretation of quantum mechanics “The Copenhagen Interpretation” and Bohr’s complementarity which says that there is no meaning of the state of a particle until it is observed and the act of observation might change it. The experiment consists of a double slit apparatus which is modified by putting a second double slit apparatus between the source and the original apparatus with certain conditions imposed on both the apparatuses using the facts of interference and diffraction. A striking paradox emerges if we consider the arguments of Bohr’s complementarity, i.e. the photon travels through both the paths simultaneously in a double slit apparatus whenever there is interference. It turns out that this paradox can be resolved only if the photon travels through one path even if interference fringes are visible.