Two Experiments to Test Bohr’s Complementarity Principle

Dhananjay P. Mehendale

Published Apr 1, 2012• 0 citations

Abstract

We suggest two possible experiments to verify the mysterious passing of single photon through both the slits simultaneously. The first experiment aims to measure polarization of photons reaching the screen using polarization detectors fixed on the screen on both sides of the midway line made up of locus of points equidistant from both the slits and further using two types of synchronization setups. Again, using the same two types of synchronization setups, we suggest the second experiment which is based on a simple idea, justified by uncertainty principle. We suggest that we can distinguish between photons that have definitely gone through both the slits simultaneously and those other photons that have gone only through any single slit, either through the one on the left side or through the other on the right side, at a time. We fix in the second experiment photon detectors on the screen on both sides of the midway line made up of locus of points equidistant from both the slits. These experiments aim at achieving experimental confirmation for complementarity principle due to N. Bohr.

Related papers

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 CommunicationsSep 13, 20213 citations

Wave Particle Duality and the Afshar Experiment

Aurélien Drezet

In an interesting series of articles published few years ago Afshar and coworkers [1,2] reported an optical experiment in which they claimed to refute the well known N. Bohr principle of complementarity [3, 4]. Obviously this result, if justified, would constitute a serious attack against the orthodox interpretation of quantum mechanics (known as the Copenhagen interpretation). This work stirred much debate in different journals (see for examples references [5–12]). We think however that there are still some important misunderstandings concerning the interpretation of this experiment. In a preprint written originally in 2004 [5] (and following some early discussions with Afshar) we claimed already that the interpretation by Afshar et al. can be easily stated if we stay as close as possible from the texts written by Bohr. The aim of the present article (which was initially written in 2005 to precise a bit the thought developed in [5]) is to comment the interpretation discussed in [1]. We will in the following analyze the meaning of Bohr principle and show that far from disproving its content the experiment [1] is actually a complete confirmation of its general validity. The difficulties associated with the understanding of this principle are not new and actually complementarity created troubles even in Einstein mind [3] so that we are here in good company. To summarize a bit emphatically Bohr’s complementarity we here remind that this principle states that if one of a pair of non commuting observables of a quantum object is known for sure, then information about the second (complementary) is lost [3, 4, 15, 16]. This can be equivalently expressed as a kind of duality between different descriptions of the quantum system associated with different experimental arrangements which mutually exclude each other (read in particular [3,4]). Later in the discussion we will try to precise this definition but for the moment it is enough to illustrate the concepts by examples Consider for instance the well known Young double-pinholes interference experiment made with photons. The discrete nature of light precludes the simultaneous observation of a same photon in the aperture plane and in the interference pattern: the photon cannot be absorbed twice. This is already a trivial manifestation of the principle of Bohr. Here it implies that the two statistical patterns associated with the wave in the aperture plane and its Fourier (i. e., momentum) transform require necessarily different photons for their recording. It is in that sense that each experiment excludes and completes reciprocally the other. In the case considered before the photon is absorbed during the first detection (this clearly precludes any other detection). However even a non-destructive solution for detection implying entanglement with other quantum systems has a radical effect of the same nature: the complementarity principle is still valid. For example, during their debate Bohr and Einstein [3] discussed an ideal which-way experiment in which the recoil of the slits is correlated to the motion of the photon. Momentum conservation added to arguments based on the uncertainty relations are sufficient to explain how such entanglement photon-slits can erase fringes [15–19]. It is also important for the present discussion to remind that the principle of complementarity has a perfidious consequence on the experimental meaning of trajectory and path followed by a particle. Indeed the unavoidable interactions existing between photons and detectors imply that a trajectory existing independently of any measurement process cannot be unambiguously defined. This sounds even like a tragedy when we consider once again the two-holes experiment. Indeed for Bohr this kind of experiments shows definitely the essential element of ambiguity which is involved in ascribing conventional physical attributes to quantum systems. Intuitively (i. e., from the point of view of classical particle dynamic) one would expect that a photon detected in the focal plane of the lens must have crossed only one of the hole 1 or 2 before to reach its final destination. However, if this is true, one can not intuitively understand how the presence of the second hole (through which the photon evidently did not go) forces the photon to participate to an interference pattern (which obviously needs an influence coming from both holes). Explanations to solve this paradox have been proposed by de Broglie, Bohm, and others using concepts such as empty waves or quantum potentials [20, 21]. However all these explanations are in agreement with Bohr principle (since they fully reproduce quantum predictions) and can not be experimentally distinguished. Bohr and Heisenberg proposed for all needed purposes a much more pragmatic and simpler answer: don’t bother, the complementarity principle precludes the simultaneous observation of a photon trajectory and of an interference pattern. For Bohr [3]: This point is of great logical consequence, since it is only the circumstance that we are presented with a choice of either tracing the path

Jan 1, 20115 citations

Observation of Which-Way-2D-Cross-Double-Slit Experiments: Violation of Bohr’s Complementarity Principle

Hui Peng

Young’s one-dimension-double-slit experiment represents the basic mystery of quantum world and was extended to which-way-1D-double-slit experiment. To explore the mystery, 2D-cross-double-slit apparatuses have been proposed, which consists of more than one double-slits intersecting to each other. In this article, we report which-way-2D-cross-double-slit experiments by detecting which slit of a double-slit of 2D-cross-double-slit apparatus a photon would pass through. The experimental results show that photons passing through the detected double-slit behave as particle, while photons passing through other undetected double-slit(s) distribute as wave in the same experiment with the same apparatus. Namely the particle nature and wave distribution coexist, which violates Bohr’s complementarity principle. We suggest that photon’s “particle nature” is intrinsic, while the term “wave nature” represents a wave-like distribution, which is a consequence of movement of photon as particle. It is a challenge to interpret mathematically those observations consistently.

International Journal of PhysicsNov 27, 20203 citations

Using double slit experiment based on Bohr complementarity principle to transmit information without media transmission from the information source to destination

ChuangRui Liu, HanRui Liu, XinHua Liu

Abstract This paper proposes information transmission without media transmission from the information source to destination based on Bohr complementarity principle. When a single photon passes through Young’s double-slit, its particle degree characteristics increase with the path distinguishability increasing. After single photon passes through double-slit, the photons propagation route is divided into two regions, the source region and the destination region. Keep the path distinguishability in the destination region unchanged. Distinguish or not distinguish the path information in the source region. The distribution of photons on each region will be different after single photons pass through double-slit. Use the laser trigger signal on the front optical path to confirm whether the photons detected at the destination region are valid photons, rather than photon information of the source region. Count the percentage of photons falling in the destination region in the photons passing through the double-slit, by pre-synchronizing to make particle degree characteristics of each photon similar in each period of time. This percentage can reveal the photon path distinguishability of the source region. The interference visibility of the fringe formed by valid photons detected at the destination region can achieve the target too.

Physica ScriptaMar 2, 20232 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, 20150 citations

Double Slit Experiment Still Has Much to Offer (2): Extended-Which-Way Experiments--- Violating Complementarity Principle

Peng, Hui

Young's 1D-dimension-double-slit experiments represent the basic mystery of quantum world and was extended to which-way-1D-double-slit experiment. To explore the mystery, 2D-cross-double-slit diaphragm have been proposed, which consists of more than one double-slits intersecting to each other at the same spot. In this article, the extended which-way 2D cross-double slit experiments are presented to test the normal interpretation of the which way experiments. The experimental results show that photons passing through the detected double-slit behave as particle, while photons passing through other undetected double-slit(s) distribute as wave in the same experiment with the same diaphragm. Namely the particle nature and wave distribution coexist, which violates Bohr's complementarity principle. It is a challenge to interpret those observations consistently.

Sep 29, 20210 citations