Wave-particle Duality Relation Research Articles

General-relativistic wave–particle duality with torsion

We propose that the four-velocity of a Dirac particle is related to its relativistic wave function by ui=ψˉγiψ/ψˉψ . This relativistic wave–particle duality relation is demonstrated for a free particle related to a plane wave in a flat spacetime. For a curved spacetime with torsion, the momentum four-vector of a spinor is related to a generator of translation, given by a covariant derivative. The spin angular momentum four-tensor of a spinor is related to a generator of rotation in the Lorentz group. We use the covariant conservation laws for the spin and energy–momentum tensors for a spinor field in the presence of the Einstein–Cartan torsion to show that if the wave satisfies the curved Dirac equation, then the four-velocity, four-momentum, and spin satisfy the classical Mathisson–Papapetrou equations of motion. We show that these equations reduce to the geodesic equation. Consequently, the motion of a particle guided by the four-velocity in the pilot-wave quantum mechanics coincides with the geodesic motion determined by spacetime. We also show how the duality and the operator form of the Mathisson–Papapetrou equations arise from the covariant Heisenberg equation of motion in the presence of torsion.

Wave-Particle Duality via Quantum Fisher Information

Abstract Quantum Fisher information (QFI) plays an important role in quantum metrology, placing the ultimate limit to how precise we can estimate some unknown parameter and thus quantifying how much information we can extract. We observe that both the wave and particle properties within a Mach-Zehnder interferometer can naturally be quantified by QFI. Firstly, the particle property can be quantified by how well one can estimate the a priori probability of the path taken by the particle within the interferometer. Secondly, as the interference pattern is always related to some phase difference, the wave property can be quantified by how well one can estimate the phase parameter of the original state. With QFI as the unified figure of merit for both properties, we propose a more general and stronger wave-particle duality relation than the original one derived by Englert.

Operational interpretation of bipartite quantum correlation

Operational interpretations of quantum resource measures lie at the heart of quantum information processing technologies. In this paper, we show that the bipartite quantum correlation in terms of Wigner-Yanase skew information, is the minimal failure probability of a particular state ensemble discrimination task via the associated least square measurement. We then derive a general relation between quantum coherence with respect to quantum operation and discriminating probability specific to least square measurement. Furthermore, we provide a wave-particle duality relation between bipartite quantum correlation and which-path information.

Experimental investigation of wave-particle duality relations in asymmetric beam interference

Wave-particle duality relations are fundamental for quantum physics. Previous experimental studies of duality relations mainly focus on the quadratic relation D2 + V2 ≤ 1, based on symmetric beam interference, while a linear form of the duality relation, predicated earlier theoretically, has never been experimentally tested. In addition, the difference between the quadratic form and the linear form has not been explored yet. In this work, with a designed asymmetric beam interference and by utilizing the polarization degree of freedom of the photon as a which-way detector, we experimentally confirm both forms of the duality relations. The results show that more path information is obtained in the quadratic case. Our findings reveal the difference between the two duality relations and have fundamental implications in better understanding these important duality relations.

Simulation of Afshar’s Double Slit Experiment

Shahriar S. Afshar claimed that his 2007 modified version of the double-slit experiment violates complementarity [1]. He makes two modifications to the standard double-slit experiment. First, he adds a wire grid that is placed in between the slits and the screen at locations of interference minima. The second modification is to place a converging lens just after the wire grid. The idea is that the wire grid implies the existence of interference minima(wave-like behavior), while the lens can simultaneously obtain which-way information (particle-like behavior). More recently, John G. Cramer [2] argued that the experiment bolstered the Transactional Interpretation of Quantum mechanics (TIQM). His argument scrutinizes Bohr's complementarity in favor of TIQM. We analyze this experiment by simulation using the path integral formulation of quantum mechanics [3] and find that it agrees with the wave particle duality relation given by Englert, Greenberg and Yasin (E-G-Y) [4, 5]. We conclude that the use of Afshar's experiment to provide a testbed for quantum mechanical interpretations is limited.

From wave-particle duality to wave-particle-mixedness triality: an uncertainty approach

The wave-particle duality, as a manifestation of Bohr’s complementarity, is usually quantified in terms of path predictability and interference visibility. Various characterizations of the wave-particle duality have been proposed from an operational perspective, most of them are in forms of inequalities, and some of them are expressed in forms of equalities by incorporating entanglement or coherence. In this work, we shed different insights into the nature of the wave-particle duality by casting it into a form of information conservation in a multi-path interferometer, with uncertainty as a unified theme. More specifically, by employing the simple yet fundamental concept of variance, we establish a resolution of unity, which can be interpreted as a complementarity relation among wave feature, particle feature, and mixedness of a quantum state. This refines or reinterprets some conventional approaches to wave-particle duality, and highlights informational aspects of the issue. The key idea of our approach lies in that a quantum state, as a Hermitian operator, can also be naturally regarded as an observable, with measurement uncertainty (in a state) and state uncertainty (in a measurement) being exploited to quantify particle feature and wave feature of a quantum state, respectively. These two kinds of uncertainties, although both are defined via variance, have fundamentally different properties and capture different features of a state. Together with the mixedness, which is a kind of uncertainty intrinsic to a quantum state, they add up to unity, and thus lead to a characterization of the wave-particle-mixedness complementarity. This triality relation is further illustrated by examples and compared with some popular wave-particle duality or triality relations.

Partial particle and wave information and weak duality games

Duality games are a way of looking at wave–particle duality. In these games. Alice and Bob together are playing against the house. The house specifies, at random, which of two sub-games Alice and Bob will play. One game, Ways, requires that they obtain path information about a particle going through an N-path interferometer and the other, Phases, requires that they obtain phase information. In general, because of wave–particle duality, Alice and Bob cannot always win the overall game. However, if the required amount of path and phase information is not too great, for example specifying a set of paths or phases, one of which is the right one, then they can always win. Here we study examples of duality games that can always be won, and develop a wave–particle duality relation expressed only in terms of mutual information to help analyze these games.

Wave–particle duality relation with a quantum N-path beamsplitter* *Project supported by the National Natural Science Foundation of China (Grant No. 61632021).

The wave–particle duality relation derived by Englert sets an upper bound of the extractable information from wave and particle properties in a two-path interferometer. Surprisingly, previous studies demonstrated that the introduction of a quantum beamsplitter in the interferometer could break the limitation of this upper bound, due to interference between wave and particle states. Along the other line, a lot of efforts have been made to generalize this relation from the two-path setup to the N-path case. Thus, it is an interesting question that whether a quantum N-path beamsplitter can break the limitation as well. This paper systemically studies the model of a quantum N-path beamsplitter, and finds that the generalized wave–particle duality relation between interference visibility and path distinguishability is also broken in certain situations. We further study the maximal extractable information’s reliance on the interference between wave and particle properties, and derive a quantitative description. We then propose an experimental methodology to verify the break of the limitation. Our work reflects the effect of quantum superposition on wave–particle duality, and exhibits a new aspect of the relation between visibility and path distinguishability in N-path interference. Moreover, it implies the observer’s influence on wave–particle duality.

Multipath wave-particle duality with a path detector in a quantum superposition

According to Bohr's principle of complementarity, a quanton can behave either as a wave or a particle, depending on the choice of the experimental setup. Some recent two-path interference experiments have devised methods where one can have a quantum superposition of the two choices, thus indicating that a quanton may be in a superposition of wave and particle nature. These experiments have been of interest from the point of view of Wheeler's delayed-choice experiment. However, it has also been claimed that this experiment can violate complementarity. Here we theoretically analyze a multipath interference experiment that has a which-path detector in a quantum superposition of being present and absent. We show that a tight multipath wave-particle duality relation is respected in all such situations, and complementarity holds well. The apparent violation of complementarity may be due to incorrect evaluation of path distinguishability in such scenarios.

Predictability, distinguishability, and entanglement.

Recent times have seen a spurt of research activity focused on "completing" certain wave-particle duality relations using entanglement or polarization. These studies use a duality relation involving path-predictability, and not path-distinguishability. Quantum origins of these results are explored here, in the more general framework of multipath quantum interference. Multipath interference with a path-detector is theoretically analyzed to find the connection between predictability and distinguishability. It is shown that entanglement is what quantitatively connects distinguishability with predictability. Thus, a duality relation between distinguishability and coherence can also be viewed as a triality between predictability, entanglement, and coherence. There exist two different kinds of duality relations in the literature, which pertain to two different kinds of interference experiments, with or without a path-detector. Results of this study show that the two duality relations are quantitatively connected via entanglement. The roots of the new, to the best of our knowledge, results in the classical optical domain, including the polarization coherence theorem, can be understood in the light of this work.

Wave-particle-duality relations based on entropic bounds for which-way information

We present wave-particle duality relations involving the relative entropy coherence measure, which plays a prominent role in the resource theory of coherence. The main input in these relations is an entropic bound for the which-way information, which we derive in this letter. We show that this latter crucially depends on the choice of the measurement strategy to obtain the path information. In particular, we present results for two strategies: zero-error identification of the path-detector states, which never produces an error but sometimes fails to return a conclusive answer, and a mixed strategy where both errors and failure are allowed.

Quantitative wave–particle duality relations from the density matrix properties

We derive upper bounds for Hilbert-Schmidt's quantum coherence of general states of a $d$-level quantum system, a qudit, in terms of its incoherent uncertainty, with the latter quantified using the linear and von Neumann's entropies of the corresponding closest incoherent state. Similar bounds are obtained for Wigner-Yanase's coherence. The reported inequalities are also given as coherence-populations trade-off relations. As an application example of these inequalities, we derive quantitative wave-particle duality relations for multi-slit interferometry. Our framework leads to the identification of predictability measures complementary to Hilbert-Schmidt's, Wigner-Yanase's, and $l_{1}$-norm quantum coherences. The quantifiers reported here for the wave and particle aspects of a quanton follow directly from the defining properties of the quantum density matrix (i.e., semi-positivity and unit trace), contrasting thus with most related results from the literature.

Multipath wave-particle duality in classical optics

It is well known that in classical optics, the visibility of interference, in a two-beam light interference, is related to the optical coherence of the two beams. A wave-particle duality relation can be derived using this mutual coherence. The issue of wave-particle duality in classical optics is analyzed here, in the more general context of multipath interference. New definitions of interference visibility and path distinguishability have been introduced, which lead to a duality relation for multipath interference. The visibility is shown to be related to a new multipoint optical coherence function.

Minimum-error state discrimination and quantitative wave particle duality

We establish the link between minimum-error discrimination of two pure states and wave particle duality in two-path interferometers. In particular, the upper bound of the probability of success discrimination is derived directly from the corresponding duality relation. It is already known that quantum state discrimination can produce wave particle duality relations, here we show the converse is also true: Wave particle duality can be used to obtain information about state discrimination.

Interference visibility and wave-particle duality in multipath interference

Wave-particle duality in multi-path interference is fraught with issues despite substantial progress in recent years. It was experimentally shown that in certain specific conditions, getting path information in a multi-path experiment can actually increase the visibility of interference. As a result, it was argued that in multi-path interference experiments, visibility of interference and 'which-path' information are not always complementary observables. In the present work, a new wave-particle duality relation is presented, based on a sum of visibilities of interference from individual pairs of path. This relation is always respected, even in the kind of specific situations mentioned above. This sum of visibilities turns out to be related to a recently introduced measure of coherence. As one of the consequences, it provides a novel way of experimentally measuring coherence in a multi-path interference experiment. As another consequence, this relation suggests a simple way of measuring path-distinguishability in multi-path interference. In addition, it resolves several outstanding issues concerning wave-particle duality in multi-path interference.

Coherence, Interference and Visibility

The interference observed for a quanton, traversing more than one path, is believed to characterize its wave nature. Conventionally, the sharpness of interference has been quantified by its visibility or contrast, as defined in optics. Based on this visibility, wave-particle duality relations have been formulated for two-path interference. However, as one generalizes the situation to multi-path interference, it is found that conventional interference visibility is not a good quantifier. A recently introduced measure of quantum coherence has been shown to be a good quantifier of the wave nature. The subject of quantum coherence, in relation to the wave nature of quantons and to interference visibility, is reviewed here. It is argued that coherence can be construed as a more general form of interference visibility, if the visibility is measured in a different manner, and not as contrast.Quanta 2019; 8: 24–35.

A Physical Interpretation of de Broglie's Wave-Particle Duality and Calculation of Lower Limit of the Mass of a Phonon

In this article, it has been shown that the wave nature of a moving particle is the wave nature of its trajectory. Using Planck's postulates for black body radiation and wave particle duality relation of de Broglie we can get a relation between mass of a phonon and emission frequency of a body at different temperatures. Using boundary conditions, lower limit of mass of a phonon is calculated and presented here. Lower limit of mass of a phonon is 7.36 X 10-51kg.

A generalized wave-particle duality relation for finite groups

Wave-particle duality relations express the fact that knowledge about the path a particle took suppresses information about its wave-like properties, in particular, its ability to generate an interference pattern. Recently, duality relations in which the wave-like properties are quantified by using measures of quantum coherence have been proposed. Quantum coherence can be generalized to a property called group asymmetry. Here we derive a generalized duality relation involving group asymmetry, which is closely related to the success probability of discriminating between the actions of the elements of a group. The second quantity in the duality relation, the one generalizing which path information, is related to information about the irreducible representations that make up the group representation.

The Bose-Einstein condensate temperature of an ideal blackbody

The oscillators of a perfect blackbody are considered as non-interacting entities. Thus, Bose-Einstein Condensation is possible for these entities. The Bose-Einstein Condensate (BEC) temperature of a perfect blackbody is calculated from the Planck’s theory of blackbody radiation and de Broggle’s wave-particle duality relation. It is observed that the BEC temperature of an ideal blackbody is 4.0K. Thus, bellow 4.0K temperature the energy density vs wavelength plot of a blackbody would look like a delta function. In this region, a blackbody would absorb or emit radiation of unique frequency depending upon its temperature. It is also possible to calculate the rest mass and the ground state vibrational energy of the oscillators of a blackbody using present formalism.

Theoretical lower limit of mass of phonon and critical mass for matter–dark matter conversion

From Planck’s equation for black body radiation and de Broglie’s wave–particle duality relation, we can get a relation between the mass of a phonon and frequency of the emitted radiation. From this relation, we get the theoretical lower limit of the mass of a phonon and critical mass for matter–dark matter conversion. The maximum matter density and limit of the string length are also discussed in this respect. It is observed that there is a critical mass of the smallest particle, which is $$7.367 \times 10^{-51}$$ kg, above which we get normal matter and below, the dark matter. It is also observed that if phonon obeys the de Broglie’s equation, generation of an electromagnetic radiation of frequency less than 56638721410 Hz is not possible by thermal heating.