Neutrino orbital angular momentum in a plasma vortex

Mendonça, J. T.; Thidé, Bo

doi:10.1209/0295-5075/84/41001

Cited by 27 publications

(16 citation statements)

References 23 publications

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“…High OAM values may also occur in particular situations of radial polar accretion 29 or from the gravitational lensing of coherent astrophysical sources. The OAM mechanism described here should be valid also for neutrino fields 30 . Our results can be extended to more general situations such as in the latest stages of BH-BH collisions or in generalizations of Kerr metrics.…”

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confidence: 92%

Twisting of light around rotating black holes

Tamburini¹,

et al. 2011

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Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory 1,2 . These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light emitted near them. We have found that this leads to a new relativistic effect that imprints orbital angular momentum on such light. Numerical experiments, based on the integration of the null geodesic equations of light from orbiting point-like sources in the Kerr black hole equatorial plane to an asymptotic observer 3 , indeed identify the phase change and wavefront warping and predict the associated light-beam orbital angular momentum spectra 4 . Setting up the best existing telescopes properly, it should be possible to detect and measure this twisted light, thus allowing a direct observational demonstration of the existence of rotating black holes. As non-rotating objects are more an exception than a rule in the Universe, our findings are of fundamental importance.In curved spacetime geometries, the direction of a vector is generally not preserved when parallel-transported from one event to another, and light beams are deflected because of gravitational lensing. If the source of the gravitational field also rotates, it drags spacetime with it, causing linearly polarized electromagnetic radiation to undergo polarization rotation similar to the Faraday rotation of light in a magnetized medium. This is known as the gravitational Faraday effect 5 . As a result of the rotation of the central mass, each photon of a light beam propagating along a null geodesic will experience a well-defined phase variation. As a result, the beam will be transformed into a superposition of photon eigenstates, each with a well-defined value sh of spin angular momentum and h of orbital angular momentum 6 . Patterns drawn by such beams experience an anamorphosis 7 with polarization rotation due to the gravitational Faraday effect, accompanied by image deformation and rotation due to the gravitational Berry phase effect 8,9 . Hence, light propagating near rotating black holes experiences behaviour analogous to light propagating in an inhomogeneous, anisotropic medium in which spin-to-orbital angular momentum conversion occurs 10 .Whereas the linear momentum of light is connected with radiation pressure and force action, the total angular momentum J = S + L is connected with torque action. The spin-like form S, also known as spin angular momentum (SAM), is associated with photon helicity and hence with the polarization of light. The second form, L, is associated with the orbital phase profile of the beam, measured in the direction orthogonal to the propagation axis, and is also known as orbital angular momentum (OAM). This physical observable, which is present in natural light, finds practical applications in nanotechnology 11 , communication technology 12 and many other fields. In observational astronomy, OAM of light [13][14][15] can improve the resolving power of diffraction-limited optical instrument...

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confidence: 92%

Twisting of light around rotating black holes

Tamburini¹,

et al. 2011

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“…6, and a more detailed theoretical analysis was given recently by studying the electromagnetic wave scattering from the plasma medium, with the associated OAM exchanges between the plasma and probing photon beams [7]. A more speculative work was also recently published where the strong similarities between photon and neutrino dispersion relations were explored, and OAM states of neutrino beams interacting with dense plasmas were considered [8].…”

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confidence: 99%

Stimulated Raman and Brillouin Backscattering of Collimated Beams Carrying Orbital Angular Momentum

Mendonça¹,

2009

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We study theoretically the exchange of angular momentum between electromagnetic and electrostatic waves in a plasma, due to the stimulated Raman and Brillouin backscattering processes. Angular momentum states for plasmon and phonon fields are introduced for the first time. We demonstrate that these states can be excited by nonlinear wave mixing, associated with the scattering processes. This could be relevant for plasma diagnostics, both in laboratory and in space. Nonlinearly coupled paraxial equations and instability growth rates are derived. PACS numbers:It is well known that the angular momentum of electromagnetic radiation contains two distinct parts, one associated with its polarization state, or photon spin, the other being the external or orbital photon angular momentum (OAM). With the advent of laser beams, an increasing interest is being given to the study of photon OAM, and various optical experimental configurations have been considered [1,2,3,4]. It is now well understood that collimated electromagnetic beams, such as laser or radio wave beams, can be described by LaguerreGaussian functions, which provide a natural orthonormal basis for a generic beam representation. Utilization of photon OAM states in the low frequency (≤ GHz) radio wave domain was also recently proposed in Ref. 5, as a new method for studying and characterizing radio sources in astrophysics.The possibility of remote study of space plasma vorticity by measuring the OAM of radio beams interacting with vortical plasmas was pointed out in Ref. 6, and a more detailed theoretical analysis was given recently by studying the electromagnetic wave scattering from the plasma medium, with the associated OAM exchanges between the plasma and probing photon beams [7]. A more speculative work was also recently published where the strong similarities between photon and neutrino dispersion relations were explored, and OAM states of neutrino beams interacting with dense plasmas were considered [8].Here we consider the important problem of stimulated Raman and Brillouin backscattering of collimated electromagnetic beams with finite OAM in a plasma. This also leads us to consider, to our knowledge for the first * Electronic address: titomend@ist.utl.pt † Also at LOIS Space Centre, Växjö University, SE-351 95 Växjö, Sweden time, the possible existence of plasmon and phonon states with finite orbital angular momentum. Raman and Brillouin scattering instabilities are well known in the context of laser fusion [9], as possible sources of anomalous plasma reflectivity. Raman backscattering is now recognized as a dominant process for ultra-intense laser plasma interactions, in the context of inertial fusion research [10]. In all these studies, angular momentum in general, and photon OAM in particular, have been systematically ignored. On the other hand, there seems to be experimental evidence of OAM dependence in Brillouin scattering of radio waves in the ionosphere [11], which awaits for a deeper theoretical understanding. In contrast with the traditional t...

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“…As is the case for electromagnetic linear momentum, elec-tromagnetic angular momentum can propagate not only in free space, but also in-and interact with-various propagation media [117,119], including plasmas [9,[151][152][153][154][155][156]. This includes waveguides [157] and optical fibers [79,158,159], where the decay rate, due to absorption, is the same for the propagation of angular momentum as for linear momentum since they are both bilinear in the same electric and magnetic fields.…”

Section: Complex Notationmentioning

confidence: 99%

The physics of angular momentum radio

Thidé

Tamburini

2015

2015 1st URSI Atlantic Radio Science Conference (URSI AT-RASC)

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To this day, wireless communications, as well as radio astronomy and other radio science and technology applications, have made predominantly use of techniques built on top of the electromagnetic linear momentum physical layer. As a supplement and/or alternative to this conventional approach, techniques rooted in the electromagnetic angular momentum (moment of momentum) physical layer have been advocated, and promising results from proof-of-concept laboratory and real-world angular momentum wireless and fiber communication experiments were recently reported. A physical observable in its own right, albeit much more sparingly used than other electromagnetic observables such as energy and linear momentum, the angular momentum exploits the rotational symmetry of the electromagnetic field and the rotational (spinning and orbiting) dynamics of the pertinent charge and current densities. Here we present a review of the fundamental physical properties of the electromagnetic angular momentum observable, derived from the fundamental postulates of classical electrodynamics (the Maxwell-Lorentz equations), and put it into its context among the other Poincaré symmetry invariants of the electromagnetic field. The multi-mode quantized character and other physical properties that sets the classical electromagnetic angular momentum apart from the electromagnetic linear momentum are pointed out. We give many of the results both in terms of the electric and magnetic field vectors and in terms of the complex Riemann-Silberstein vector formalism (Majorana-Oppenheimer representation of classical electrodynamics) and discuss formal parallels with first quantization formalism. We introduce generalized and symmetrized extensions of the Jefimenko integral formulas for calculating exact expressions for the electric and magnetic fields directly from arbitrary given electric and/or magnetic source distributions and use them for deriving expressions for the volumetric density of the electromagnetic angular momentum radiated from any given arbitrary localized distribution of charges and currents. Our results generalize earlier results, obtained by other authors for certain specific configurations only, and facilitate the modeling and design of angular momentum transducers. They show that the volume integrated angular momentum density, i.e., the total angular momentum emitted by the sources, always tends asymptotically to a constant when the distance from the source volume tends to infinity, proving that a radiation arrow of time exists also for angular momentum, as it does for linear momentum (the volume integrated Poynting vector). Consequently, angular momentum physics (torque action) offers an alternative or a supplement to linear momentum physics (force action) as a means of transferring information wirelessly over very long distances. This finding opens possibilities for, among other things, a more flexible utilization of the radio frequency spectrum and paves the way for the development of new information transfer techniques. We discuss ...

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Neutrino orbital angular momentum in a plasma vortex

Cited by 27 publications

References 23 publications

Twisting of light around rotating black holes

Twisting of light around rotating black holes

Stimulated Raman and Brillouin Backscattering of Collimated Beams Carrying Orbital Angular Momentum

The physics of angular momentum radio

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