Optical Instabilities and Spontaneous Light Emission by Polarizable Moving Matter

Silveirinha, Mário G.

doi:10.1103/physrevx.4.031013

Cited by 49 publications

(82 citation statements)

References 37 publications

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“…5), highlighting the different nature of the MI compared to the (bulk) twostream and current filamentation instabilities. This setting is closely connected to the work explored in [35] on the development of electromagnetic instabilities between shearing polarizable dielectric slabs, separated by a nanometer-scale gap; the development of such instabilities results in an effective noncontact friction force between slabs [36], which is the classical analog to the quantum friction effect identified in [37]. The role of the MI, however, was overlooked since only subrelativistic configurations were considered; the transverse MI modes will be predominant in the relativistic regime.…”

Section: -3mentioning

confidence: 79%

Transverse electron-scale instability in relativistic shear flows

et al. 2015

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Electron-scale surface waves are shown to be unstable in the transverse plane of a sheared flow in an initially unmagnetized collisionless plasma, not captured by (magneto)hydrodynamics. It is found that these unstable modes have a higher growth rate than the closely related electron-scale Kelvin-Helmholtz instability in relativistic shears. Multidimensional particle-in-cell simulations verify the analytic results and further reveal the emergence of mushroomlike electron density structures in the nonlinear phase of the instability, similar to those observed in the Rayleigh Taylor instability despite the great disparity in scales and different underlying physics. This transverse electron-scale instability may play an important role in relativistic and supersonic sheared flow scenarios, which are stable at the (magneto)hydrodynamic level. Macroscopic ( c/ω pe ) fields are shown to be generated by this microscopic shear instability, which are relevant for particle acceleration, radiation emission, and to seed magnetohydrodynamic processes at long time scales. A fundamental question in plasma physics concerns the stability of a given plasma configuration. Unstable plasma configurations are ubiquitous and constitute important dissipation sites via the operation of plasma instabilities, which typically convert plasma kinetic energy into thermal and electric or magnetic field energy. Plasma instabilities can occur at microscopic (particle kinetic) and macroscopic [magnetohydrodynamic (MHD)] scales, and are generally studied separately using simplified frameworks that focus on a particular scale and neglect the other. This approach conceals the role that microscopic processes may have on the macroscopic plasma dynamics, which in many scenarios cannot be disregarded. It is now recognized, for instance, that collisionless plasma instabilities operating on the electron scale in unmagnetized plasmas, such as the Weibel [1] and streaming instabilities [2], play a crucial role in the formation of (macroscopic) collisionless shocks in astrophysical [3][4][5][6][7] and laboratory conditions [8,9]. These microscopic instabilities result from the bulk interpenetration between plasmas and are believed to be intimately connected to important questions such as particle acceleration and radiation emission in astrophysical scenarios [10,11].Sheared plasma flow configurations can host both microscopic and macroscopic instabilities simultaneously, although the former have been largely overlooked. Sheared flow settings have been traditionally studied using the MHD framework [12][13][14], where the Kelvin-Helmholtz instability (KHI) is the only instability known to develop [15]. Only very recently have collisionless unmagnetized sheared plasma flows been addressed experimentally [16] and using particle-in-cell (PIC) simulations, revealing a rich variety of electron-scale processes, such as the electron-scale KHI (ESKHI), dc magnetic field generation, and unstable transverse dynamics [17][18][19][20][21][22]. The generated fields and modif...

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Section: -3mentioning

confidence: 79%

Transverse electron-scale instability in relativistic shear flows

et al. 2015

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“…Another situation is when a particle is moving through a small channel drilled into a dielectric or parallel to a surface [7,[13][14][15][16][17][18]23]. A recent work [21,22], also explores quantum friction beyond Cherenkov velocity. There are discrepancies between the results of this work and a large number of papers devoted to the study of quantum friction, which need to be further investigated.…”

Section: Basic Results Of a Fully Relativistic Theory Of Friction Betmentioning

confidence: 99%

“…The problem of friction for a small neutral particle moving parallel to a solid surface (particle-surface configuration) was considered by number of authors (see [7,[13][14][15][16][17][18], and references therein). At present the interest in this problem is increasing because it is linked to quantum Cherenkov radiation [19][20][21][22][23]. Recently a fully covariant theory of friction in particle-surface configuration was proposed by Pieplow and Henkel (PH) [14] and comparison with results of previous authors was given.…”

Section: Introductionmentioning

confidence: 99%

Comment on ‘Fully covariant radiation force on a polarizable particle’

Volokitin

Persson

2014

New J. Phys.

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Recently Pieplow and Henkel (2013 New J. Phys. 15 023027) presented a new fully covariant theory of the Casimir friction force acting on small neutral particle moving parallel to flat surface. We compare results of this theory with results which follow from a fully relativistic theory of friction in plate-plate configurations in the limit when one plate is considered as sufficiently rarefied. We show that there is agreement between these theories.

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“…Supposing that the region above the material substrate in Fig. 1b is a vacuum, the interaction tensor is given by [42,52]    …”

Section: Discussionmentioning

confidence: 99%

Spontaneous rotational symmetry breaking in a Kramers two-level system

Silveirinha

2019

Phys. Rev. B

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Here, I develop a model for a two-level system that respects the time-reversal symmetry of the atom Hamiltonian and the Kramers theorem. The two-level system is formed by two Kramers pairs of excited and ground states. It is shown that due to the spin-orbit interaction it is in general impossible to find a basis of atomic states for which the crossed transition dipole moment vanishes. The parametric electric polarizability of the Kramers two-level system for a definite ground-state is generically nonreciprocal. I apply the developed formalism to study Casimir-Polder forces and torques when the two-level system is placed nearby either a reciprocal or a nonreciprocal substrate. In particular, I investigate the stable equilibrium orientation of the two-level system when both the atom and the reciprocal substrate have symmetry of revolution about some axis. Surprisingly, it is found that when chiral-type dipole transitions are dominant the stable ground state is not the one in which the symmetry axes of the atom and substrate are aligned. The reason is that the rotational symmetry may be spontaneously broken by the quantum vacuum fluctuations, so that the ground state has less symmetry than the system itself.

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Optical Instabilities and Spontaneous Light Emission by Polarizable Moving Matter

Cited by 49 publications

References 37 publications

Transverse electron-scale instability in relativistic shear flows

Transverse electron-scale instability in relativistic shear flows

Comment on ‘Fully covariant radiation force on a polarizable particle’

Spontaneous rotational symmetry breaking in a Kramers two-level system

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