614 research outputs found
BPS Skyrme neutron stars in generalized gravity
We study the coupling of nuclear matter described by the BPS Skyrme model to
generalized gravity. Concretely, we consider the Starobinsky model which
provides the leading-order correction to the Einstein-Hilbert action. Static
solutions describing neutron stars are found both for the full field theory and
for the mean-field approximation. We always consider the full Starobinsky model
in the nonperturbative approach, using appropriately generalized shooting
methods for the numerical neutron star calculations. Many of our results are
similar to previous investigations of neutron stars for the Starobinsky model
using other models of nuclear matter, but there are some surprizing
discrepancies. The "Newtonian mass" relevant for the surface redshift, e.g.,
results larger than the ADM mass in our model, in contrast to other
investigations. This difference is related to the particularly high stiffness
of nuclear matter described by the BPS Skyrme model and offers an interesting
possibility to distinguish different models of nuclear matter within
generalized gravity.Comment: LaTex, 28 pages, 13 figures; v2: minor change
The effects of retardation on the topological plasmonic chain: plasmonic edge states beyond the quasistatic limit
We study a one-dimensional plasmonic system with non-trivial topology: a
chain of metallic nanoparticles with alternating spacing, which is the
plasmonic analogue to the Su-Schreiffer-Heeger model. We extend previous
efforts by including long range hopping with retardation and radiative damping,
which leads to a non-Hermitian Hamiltonian with frequency dependence. We
calculate band structures numerically and show that topological features such
as quantised Zak phase persist due to chiral symmetry. This predicts parameters
leading to topologically protected edge modes, which allows for positioning of
disorder-robust hotspots at topological interfaces, opening up novel
nanophotonics applications
Transformation optics for plasmonics: from metasurfaces to excitonic strong coupling Optique transformationnelle pour la plasmonique : des métasurfaces à l’excitonique en fort couplage
We review the latest theoretical advances in the application of the framework of Transformation
Optics for the analytical description of deeply sub-wavelength electromagnetic phenomena. First, we present a general description of the technique, together with its usual exploitation for metamaterial conception and optimization in different areas of wave physics. Next, we discuss in detail the design of plasmonic metasurfaces, including the description of singular geometries which allow for broadband absorption in ultrathin platforms. Finally, we discuss the quasi-analytical treatment of plasmon–exciton strong coupling in nanocavities at the single emitter levelA.I.F.-D. acknowledges funding from the Spanish MICINN under Contract RTI2018-099737-B-I00 and the “MarĂa de Maeztu” programme for Units of Excellence in R&D (MDM-2014-0377). He was also supported by a 2019 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation
Plasmonic Brownian ratchet
Here we present a Brownian ratchet based on plasmonic interactions. By
periodically turning on and off a laser beam that illuminates a periodic array
of plasmonic nanostructures with broken spatial symmetry, the random thermal
motion of a subwavelength dielectric bead is rectified into one direction. By
means of the Molecular Dynamics technique we show a statistical directed drift
in particle flow
Bound states in the continuum in subwavelength emitter arrays
Ordered lattices of emitters with subwavelength periodicities support
unconventional forms of light-matter interactions arising from collective
effects. Here, we propose the realization and control of subradiant optical
states within the radiation continuum in two-dimensional lattices. We show how
bound states in the continuum (BICs) which are completely decoupled from
radiative states emerge in non-Bravais lattices of emitters. Symmetry breaking
results in quasi-BICs with greatly extended lifetimes, which can be exploited
for quantum information storage. The analytical derivation of a generalized
effective polarizability tensor allows us to study the optical response of
these arrays. We discuss how thanks to the quasi-BICs, a rich phenomenology
takes place in the reflectivity spectrum, with asymmetric Fano resonances and
an electromagnetically induced transparency window. Finally, we exploit these
lattices as quantum metasurfaces acting as efficient light polarizers
An Archimedes' Screw for Light
An Archimedes' Screw captures water, feeding energy into it by lifting it to
a higher level. We introduce the first instance of an optical Archimedes'
Screw, and demonstrate how this system is capable of capturing light, dragging
it and amplifying it. We unveil new exact analytic solutions to Maxwell's
Equations for a wide family of chiral space-time media, and show their
potential to achieve chirally selective amplification within widely tunable
parity-time-broken phases. Our work, which may be readily implemented via
pump-probe experiments with circularly polarized beams, opens a new direction
in the physics of time-varying media by merging the rising field of space-time
metamaterials and that of chiral systems, and may form a new playground for
topology and non-Hermitian physics, with potential applications to chiral
spectroscopy and sensing
Photon localisation and Bloch symmetry breaking in luminal gratings
In gratings travelling at nearly the velocity of light a symmetry breaking
transition is observed between free-flowing fluid-like Bloch waves observed at
lower grating velocities and, at luminal velocities, condensed, localised
states of light captured in each period of the grating and locked to its
velocity. We introduce a new technique for calculating in this regime and use
it to study the transition in detail shedding light on the critical exponents,
and the periodic oscillations in transmitted intensity seen in the
pre-transition regime.Comment: 11 pages, 5 figure
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