Canonical quantization of the electromagnetic field interacting with a moving dielectric medium

Copyright © 2012 American Physical SocietyThe electromagnetic field is canonically quantized in the presence of a linear, dispersive, and dissipative medium that is in uniform motion. Specifically we calculate the change in the normal modes of the coupled matter-field system and find a Hamiltonian that contains negative-energy normal modes. We interpret these modes as the origin of phenomena such as quantum friction and find that a detector initially in its ground state and coupled to the electromagnetic field in the vicinity of, or within, a uniformly moving medium has a nonzero probability of excitation at T=0 K

Consistency of certain constitutive relations with quantum electromagnetism

Copyright © 2011 American Physical SocietyRecent work by Philbin [ New J. Phys. 12 123008 (2010)] has provided a Lagrangian theory that establishes a general method for the canonical quantization of the electromagnetic field in any dispersive, lossy, linear dielectric. Working from this theory, we extend the Lagrangian description to reciprocal and nonreciprocal magnetoelectric (bianisotropic) media, showing that some versions of the constitutive relations are inconsistent with a real Lagrangian, and hence with quantization. This amounts to a restriction on the magnitude of the magnetoelectric coupling. Moreover, from the point of view of quantization, moving media are shown to be fundamentally different from stationary magnetoelectrics, despite the formal similarity in the constitutive relations

One dimensional electromagnetic waves on flat surfaces

Author version of article. The version of record is available as an open access article from the publisher via doi: http://dx.doi.org/10.1088/0022-3727/47/43/435103© 2014 IOP Publishing LtdWe show that one-dimensional electromagnetic waves can be constrained to propagate along a join between two thin sheets when one surface supports transverse magnetic polarized surface waves and the other supports transverse electric polarized surface waves. We calculate the dispersion relation of these modes and show that they are exceptionally tightly confined to the join, with characteristic decay lengths an order of magnitude smaller than the surface waves supported by each individual surface. We give an example of a metasurface implementation where low frequency instances of such waves may be observed.Engineering and Physical Sciences Research Council (EPSRC

Radiation pressure in stratified moving media

Copyright © 2012 American Physical SocietyA general theory of optical forces on moving bodies is here developed in terms of generalized 4×4 transfer and scattering matrices. Results are presented for a planar dielectric of arbitrary refractive index placed in an otherwise empty space and moving parallel and perpendicular to the slab-vacuum interface. In both regimes of motion the resulting force comprises lateral and normal velocity-dependent components, which may depend in a subtle way on the Doppler effect and s-p-polarization mixing. For lateral displacements in particular, polarization mixing, which is here interpreted as an effective magnetoelectric effect due to the reduced symmetry induced by the motion of the slab, gives rise to a velocity-dependent force contribution that is sensitive to the phase difference between the two polarization amplitudes. This term gives rise to a rather peculiar optical response on the moving body, and specific cases are illustrated for incident radiation of arbitrarily directed linear polarization. The additional force due to polarization mixing may cancel to first order in V/c with the first order Doppler contribution yielding an overall vanishing of the velocity-dependent component of the force on the body. The above findings bear some relevance to modern developments of nano-optomechanics and to the problem of the frictional component of the Casimir force

Active absorption of electromagnetic pulses in a cavity

7 pages, 4 figuresAuthor version of the article. The version of record is available from the publisher via: http://dx.doi.org/10.1088/1367-2630/17/5/053050 and is an open access article.© 2015 IOP Publishing Ltd and Deutsche Physikalische GesellschaftWe show that a pulse of electromagnetic radiation launched into a cavity can be completely absorbed into an infinitesimal region of space, provided one has a high degree of control over the current flowing through this region. We work out explicit examples of this effect in a cubic cavity and a cylindrical one, and experimentally demonstrate the effect in the microwave regime.Engineering and Physical Sciences Research Council (EPSRC)Czech Science Foundatio

Removing singular refractive indices with sculpted surfaces

Open Access JournalThe advent of Transformation Optics established the link between geometry and material properties, and has resulted in a degree of control over electromagnetic fields that was previously impossible. For waves confined to a surface it is known that there is a simpler, but related, geometrical equivalence between the surface shape and the refractive index, and here we demonstrate that conventional devices possessing a singularity - that is, the requirement of an infinite refractive index - can be realised for waves confined to an appropriately sculpted surface. In particular, we redesign three singular omnidirectional devices: the Eaton lens, the generalized Maxwell Fish-Eye, and the invisible sphere. Our designs perfectly reproduce the behaviour of these singular devices, and can be achieved with simple isotropic media of low refractive index contrast.Engineering and Physical Sciences Research Council (EPSRC

Topological Phases for Composite Particles with Dynamic Properties

We show that, if a given electromagnetic property of a particle is allowed to vary during an evolution where the particle will accrue a topological phase, then it is both the time average and the statistical variance of this property which will affect the observable phenomena. The time average is shown to affect the topological aspect of the phase. This is in addition to a second smaller dynamical phase term, which depends upon only the variance of the changing property. The theory is illustrated in reference to the time dependence of the dipole moment in both the Aharonov-Casher and He-McKellar-Wilkens effects

Reflection of waves from slowly decaying complex permittivity profiles

Wave propagation through rapidly but continuously varying media is surprisingly subtle, and in a pair of recent papers [Horsley, J. Opt. 18, 044016 (2016)2040-897810.1088/2040-8978/18/4/044016; Longhi, Eur. Phys. Lett. 112, 64001 (2015)EULEEJ0295-507510.1209/0295-5075/112/64001] it was found that planar media with a spatially varying permittivity ϵ(x) obeying the spatial Kramers-Kronig relations do not reflect waves incident from one side, however rapid the changes in ϵ(x). Within this large class of media there are some examples where the dissipation or gain is not asymptotically negligible and it has been pointed out [Longhi, Eur. Phys. Lett. 112, 64001 (2015)EULEEJ0295-507510.1209/0295-5075/112/64001] that it is impossible to define meaningful reflection and transmission coefficients in such cases. Here we show - using an exactly soluble example - that despite the lack of any meaningful reflection and transmission coefficients, these profiles are still reflectionless from one side in the sense that the profile generates no counterpropagating wave for incidence from one side. This finding is demonstrated through examining the propagation of pulses through the profile, where from one side we find that no second reflected pulse is generated, while from the other there is. We conclude with a discussion of the effect of truncating these infinitely extended profiles, illustrating how the reflectionless behavior may be retained over a wide range of incident angle

Invisible Random Media and Diffraction Gratings That Don’t Diffract

<div>Technical paper presented at the 2017 Defence and Security Doctoral Symposium.</div><div><br></div><div>Electromagnetic waves propagating through inhomogeneous media will, in general, be scattered in multiple directions. In practical situations this is often undesirable. In this work we discuss ways to mathematically design lossless linear isotropic graded index permittivity profiles in one and two dimensions which suppress scattering. This has some counter-intuitive implications, such as disordered media exhibiting perfect transmission, and periodic gratings which don’t diffract.</div><div><br></div

Perfect surface wave cloaks.

Author version of article. The version of record is available from the publisher via DOI: http://dx.doi.org/10.1103/PhysRevLett.111.213901© 2013 American Physical SocietyThis letter presents a method for making an uneven surface behave as a flat surface. This allows an object to be concealed (cloaked) under an uneven portion of the surface, without disturbing the wave propagation on the surface. The cloaks proposed in this Letter achieve perfect cloaking that only relies upon isotropic radially dependent refractive index profiles, contrary to those previously published. In addition, these cloaks are very thin, just a fraction of a wavelength in thickness, yet can conceal electrically large objects. While this paper focuses on cloaking electromagnetic surface waves, the theory is also valid for other types of surface waves. The performance of these cloaks is simulated using dielectric filled waveguide geometries, and the curvature of the surface is shown to be rendered invisible, hiding any object positioned underneath. Finally, a transformation of the required dielectric slab permittivity was performed for surface wave propagation, demonstrating the practical applicability of this technique.Engineering and Physical Sciences Research Council (EPSRC