Backflow in relativistic wave equations

Bialynicki‐Birula, Iwo; Bialynicka‐Birula, Zofia; Augustynowicz, Szymon

doi:10.1088/1751-8121/ac65c1

Cited by 15 publications

(15 citation statements)

References 20 publications

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“…This confirms us that backflow is a non-classical effect occurring in all non-classical dynamical regimes, including quantum mechanics. This should not be confused with the fact that this effect is seen even for classical waves [8]. The important point is that the backflow is an interference phenomenon which itself has a wave nature [11,12].…”

Section: Discussionmentioning

confidence: 99%

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Different routes to the classical limit of backflow

Mousavi,

Miret-Artes

2022

Preprint

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Decoherence is a well established process for the emergence of classical mechanics in open quantum systems.However, it can have two different origins or mechanisms depending on the dynamics one is considering, speaking then about intrinsic decoherence for isolated systems and environmental decoherence due to dissipation/fluctuations for open systems. This second mechanism can not be considered for backflow since no thermal fluctuation terms can be added in the formalism in order to keep an important requirement for the occurrence of this effect: only contributions of positive momenta along time should be maintained. The purpose of this work is to analyze the backflow effect in the light of the underlying intrinsic decoherence and the dissipative dynamics. For this goal, we first deal with the Milburn approach where a mean frequency of the unitary evolution steps undergone for the system is assumed. A comparative analysis is carried out in terms of the Lindblad master equation. Second, the so-called quantum-to-classical transition wave equation is analyzed from a linear scaled Schrödinger equation which is derived and expressed in terms of a continuous parameter covering from the quantum to the classical regime as well as all in-between dynamical non-classical regimes. This theoretical analysis is inspired by the Wentzel-Kramers-Brillouin approximation. And third, in order to complete our analysis, the transition wave equation formalism is also applied to dissipative backflow within the Caldirola-Kanai approach where the dissipative dynamics comes from an effective Hamiltonian. In all the cases treated here, backflow is gradually suppressed as the intrinsic decoherence process is developing, paying a special attention to the classical limit. The route to classicality is not unique.

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Section: Discussionmentioning

confidence: 99%

“…This effect has also been studied in the presence of a constant force [4] and extended to the realm of relativistic quantum mechanics [5,6,7,8]. Its connection to arrival times [9,10], diffraction in time [11] and quantum reentry [12] have been considered.…”

Section: Introductionmentioning

confidence: 99%

Different routes to the classical limit of backflow

Mousavi,

Miret-Artes

2022

Preprint

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“…The stated goal of [1] is to argue that 'the phenomenon of backflow is a common feature of various physical system[s], quantum and classical, described by the linear wave equations'. The authors challenge a perceived view that 'backflow is inseparably connected with quantum theory'.…”

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confidence: 99%

Comment on ‘Backflow in relativistic wave equations’

Barbier

Fewster

Goussev

et al. 2023

J. Phys. A: Math. Theor.

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“…At this point, we would like to outline the equivalence between the definition of backflow in electromagnetic waves in free space and the aforementioned definition in the wave vector picture. Backflow in electromagnetism [11,21], is the counterintuitive direction of the Poynting vector. Specifically, in some regions of space the resultant Poynting vector points in a direction not contained among the directions of the constituent plane waves, i.e.…”

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confidence: 99%

“…The common understanding in all of these works is that backflow is, just as in the double slit interference of matter waves, a manifestation of the wave nature of quantum particles. Other theoretical studies [10,11] show that backflow is a versatile phenomenon that occurs in any system supporting coherent waves interference, including quantum mechanical wave-functions (where the probability density flows backwards) and classical waves (where the energy density flows backwards). Here, we shed light on the classical wave-like picture of backflow by introducing a simple experimental demonstration with electromagnetic waves.…”

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confidence: 99%

Demonstrating backflow in classical two beams’ interference

et al. 2022

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The well-known interference pattern of bright and dark fringes was first observed for light beams back in 1801 by Thomas Young. The maximum visibility fringes occur when the irradiance of the two beams is equal, and as the ratio of the beam intensities deviates from unity, fringe visibility decreases. An interesting outcome that might not be entirely intuitive, however, is that the wavefront of such unequal amplitude beams’ superposition will exhibit a wavy behavior. In this work, we experimentally observe the backflow phenomenon within this wavy wavefront. Backflow appears in both optics (retro- propagating light) and in quantum mechanics, where a local phase gradient is not present within the spectrum of the system. It has become an interesting subject for applications as it is closely related to superoscillations whose features are used in super resolution imaging and in a particle’s path manipulations. The first successful attempt to observe backflow was made only recently in an assembly of optical fields, by synthesizing their wavefront in a complex manner. Yet, backflow is perceived as hard to detect. Here, by utilizing interference in its most basic form, we reveal that backflow in optical fields is robust and surprisingly common, more than it was previously thought to be.

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Backflow in relativistic wave equations

Cited by 15 publications

References 20 publications

Different routes to the classical limit of backflow

Different routes to the classical limit of backflow

Comment on ‘Backflow in relativistic wave equations’

Demonstrating backflow in classical two beams’ interference

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