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

Physics Essays

An Alternative to Quantum Mechanics Part I: The Experiment of Pfleegor and Mandel

Ladislav Kocis

Published Sep 1, 1999• 0 citations
Publisher

Abstract

The Pfleegor-Mandel experiment showing the interference between two beams coming from two independent lasers is reviewed. It is argued that the interference fringes detected by Pfleegor and Mandel may not be caused by the interference, which is an interaction between the two beams. Instead of the interference between the two beams coming from two lasers, the following is suggested. The photons coming from the first laser interact with the environment of the path leading from the second laser, and the photons coming from the second laser interact with the environment of the path leading from the first laser. A modification of the Pfleegor-Mandel experiment that eliminates the possible interaction with the path from the other laser is proposed.

DOI
10.4006/1.3025409

Related papers

Significance of Interference between Two Independent Attenuated Laser Beams

Benjamin Liebowitz

Pfleegor and Mandel produced interference effects from two separate independent laser beams when the quanta arriving at the detector were separated in time by an average of about 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}7}$ sec. If the quanta are photons (particles), then, to produce interference, each photon must store energy in the detector for an average of at least 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}7}$ sec. But J\'anossy and N\'aray have recently shown that over a period of 9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec there is no such storage, at least when the phases are random. Thus the result of Pfleegor and Mandel is in conflict with the corpuscular concept of visible light.

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields•Jan 15, 1970•3 citations

Interference of light from independent sources

David Thomas Pegg

We extend and generalize previous work on the interference of light from independent cavities that began with the suggestion of Pfleegor and Mandel [Phys. Rev. 159, 1084 (1967)] that their observed interference of laser beams should not be associated too closely with particular states of the beams but more with the detection process itself. In particular we examine how the detection of interference induces a nonrandom-phase difference between internal cavity states with initial random phases for a much broader range of such states than has previously been considered. We find that a subsequent interference measurement should give results consistent with the induced phase difference. The inclusion of more cavities in the interference measurements enables the construction in principle of a laboratory in the sense used by Aharonov and Susskind, made up of cavity fields that can serve as frames of phase reference. We also show reasonably simply how intrinsic phase coherence of a beam of light leaking from a single cavity arises for any internal cavity state, even a photon number state. Although the work presented here may have some implications for the current controversy over whether or not a typical laboratory laser produces a coherent state, it is not the purpose of this paper to enter this controversy; rather it is to examine the interesting quantum physics that arises for cavities with more general internal states.

Physical Review A•Dec 14, 2006•4 citations

Interpretation of a Recent Experiment on Interference of Photon Beams

Louis de Broglie, J. Andrade E Silva

The interpretation of an important recent experiment by Pfleegor and Mandel according to the causal formulation of the wave-particle dualism is developed. This interpretation is simpler and seems more satisfactory than that provided by the current ideas on the nature of light.

Physical Review•Aug 25, 1968•49 citations

Quantum Interference of Different Photons and Indistinguishability of Probability Amplitudes

Young-Sik Ra, Yoon-Ho KIM

This article reviews the historical and conceptual evolution of quantum physics, challenging P.A.M. Dirac’s famous dictum, “Each photon then interferes only with itself. Interference between two different photons never occurs.” We trace the progression from the early experiments by Forrester et al. and Magyar & Mandel, which first questioned this notion, to the advent of Spontaneous Parametric Down-Conversion (SPDC) following the invention of the laser and nonlinear optics. The article elucidates how D. N. Klyshko’s quantum description of SPDC laid the groundwork for the landmark Shih-Alley and Hong-Ou-Mandel (HOM) experiments, which demonstrated two-photon quantum interference and entanglement. Finally, we address the common misconception that photons must physically overlap at a beam splitter for two-photon interference to occur. We illustrate that quantum interference arises solely from the indistinguishability of probability amplitudes leading to a joint detection event, even in configurations where the photons never locally interact at a beam splitter.

Physics and High Technology•Mar 31, 2026•0 citations

Two particle interference: The Hanbury Brown Twiss and Hong Ou Mandel experiments

Christoph I Westbrook

I discuss two important quantum optics experiments which depend on two particle interference. In the years since their first demonstration many interesting and instructive variants have appeared, including the use of atoms instead of photons as the interfering particles. This chapter gives a pedagogical overview of some of these results and argues that the two effects are closely related.

quant-pharXiv:2610.30002•Oct 22, 2026•0 citations

Interference between independent photons

Henryk Paul

A comprehensive review is given of investigations, both theoretical and experimental, that demonstrate interference to take place even when the fields involved are produced by independent sources. The physical situation is rather different for coherent and incoherent fields. In the first case, where the sources are lasers, a conventional interference pattern can be observed which is adequately described by the classical theory. In the present paper, special attention is paid to the question of whether this interference persists when the two laser beams become strongly attenuated. In the second case, the sources are individual atoms excited by a pumping mechanism, that emit spontaneously and, hence, independently from each other. In those circumstances, no interference pattern can show up. However, it becomes evident from both the classical and the quantum-mechanical theory that interference effects can still be established by observing intensity correlations rather than the intensity itself. This point is discussed in greater detail. The pioneering experiments of Forrester, Gudmundson and Johnson, and Brown and Twiss are reviewed in this context. Especially interesting from the theoretical point of view is the case of two emitting atoms, since then the classical and the quantum-mechanical description differ significantly, the quantum theory predicting the intensity correlations to be distinctly stronger than those following from classical considerations. This specific quantum-mechanical feature is shown to be intimately connected with the corpuscular aspect of light.

Reviews of Modern Physics•Jan 1, 1986•147 citations
The Pfleegor-Mandel experiment showing the interference between two beams coming from two independent lasers is reviewed. It is argued that the interference fringes detected by Pfleegor and Mandel may not be caused by the interference, which is an interaction between the two beams. Instead of the interference between the two beams coming from two lasers, the following is suggested. The photons coming from the first laser interact with the environment of the path leading from the second laser, and the photons coming from the second laser interact with the environment of the path leading from the first laser. A modification of the Pfleegor-Mandel experiment that eliminates the possible interaction with the path from the other laser is proposed.
Pfleegor and Mandel produced interference effects from two separate independent laser beams when the quanta arriving at the detector were separated in time by an average of about 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}7}$ sec. If the quanta are photons (particles), then, to produce interference, each photon must store energy in the detector for an average of at least 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}7}$ sec. But J\'anossy and N\'aray have recently shown that over a period of 9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec there is no such storage, at least when the phases are random. Thus the result of Pfleegor and Mandel is in conflict with the corpuscular concept of visible light.
We extend and generalize previous work on the interference of light from independent cavities that began with the suggestion of Pfleegor and Mandel [Phys. Rev. 159, 1084 (1967)] that their observed interference of laser beams should not be associated too closely with particular states of the beams but more with the detection process itself. In particular we examine how the detection of interference induces a nonrandom-phase difference between internal cavity states with initial random phases for a much broader range of such states than has previously been considered. We find that a subsequent interference measurement should give results consistent with the induced phase difference. The inclusion of more cavities in the interference measurements enables the construction in principle of a laboratory in the sense used by Aharonov and Susskind, made up of cavity fields that can serve as frames of phase reference. We also show reasonably simply how intrinsic phase coherence of a beam of light leaking from a single cavity arises for any internal cavity state, even a photon number state. Although the work presented here may have some implications for the current controversy over whether or not a typical laboratory laser produces a coherent state, it is not the purpose of this paper to enter this controversy; rather it is to examine the interesting quantum physics that arises for cavities with more general internal states.
This article reviews the historical and conceptual evolution of quantum physics, challenging P.A.M. Dirac’s famous dictum, “Each photon then interferes only with itself. Interference between two different photons never occurs.” We trace the progression from the early experiments by Forrester et al. and Magyar & Mandel, which first questioned this notion, to the advent of Spontaneous Parametric Down-Conversion (SPDC) following the invention of the laser and nonlinear optics. The article elucidates how D. N. Klyshko’s quantum description of SPDC laid the groundwork for the landmark Shih-Alley and Hong-Ou-Mandel (HOM) experiments, which demonstrated two-photon quantum interference and entanglement. Finally, we address the common misconception that photons must physically overlap at a beam splitter for two-photon interference to occur. We illustrate that quantum interference arises solely from the indistinguishability of probability amplitudes leading to a joint detection event, even in configurations where the photons never locally interact at a beam splitter.
A comprehensive review is given of investigations, both theoretical and experimental, that demonstrate interference to take place even when the fields involved are produced by independent sources. The physical situation is rather different for coherent and incoherent fields. In the first case, where the sources are lasers, a conventional interference pattern can be observed which is adequately described by the classical theory. In the present paper, special attention is paid to the question of whether this interference persists when the two laser beams become strongly attenuated. In the second case, the sources are individual atoms excited by a pumping mechanism, that emit spontaneously and, hence, independently from each other. In those circumstances, no interference pattern can show up. However, it becomes evident from both the classical and the quantum-mechanical theory that interference effects can still be established by observing intensity correlations rather than the intensity itself. This point is discussed in greater detail. The pioneering experiments of Forrester, Gudmundson and Johnson, and Brown and Twiss are reviewed in this context. Especially interesting from the theoretical point of view is the case of two emitting atoms, since then the classical and the quantum-mechanical description differ significantly, the quantum theory predicting the intensity correlations to be distinctly stronger than those following from classical considerations. This specific quantum-mechanical feature is shown to be intimately connected with the corpuscular aspect of light.