We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particles and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We...

Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response of metals. We predict the existence of a new class of plasmons-chiral Berry plasmons (CBPs)-for a wide range of 2D metallic systems including gapped Dirac materials. As we show, in these materials the interplay between Berry curvature and electron-electron int...

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We show that the scattering interaction between a high energy electron and a photon can be strongly enhanced by dif...

Optical imaging and photolithography promise broad applications in nano-electronics, metrologies, and single-molecule biology. Light diffraction however sets a fundamental limit on optical resolution, and it poses a critical challenge to the down-scaling of nano-scale manufacturing. Surface plasmons have been used to circumvent the diffraction limit as they have shorter wavelengths. However, th...

The screening properties and collective excitations (plasmons) in AA-stacked bilayer graphene are studied within the random phase approximation. Whereas long-lived plasmons in single-layer graphene and in AB-stacked bilayer graphene can exist only in doped samples, we find that coherent plasmons can disperse in AA-stacked bilayer graphene even in the absence of doping. Moreover, we show that th...

Structuring metallic surfaces allows for the support of surface electromagnetic modes at frequencies which they would not be allowed smooth surfaces. These are called ``spoof plasmons'' because their similarity to plasmons that supported optical This article describes physics underlies behavior spoof and how these used in applications require manipulation fields below optical.

Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology...

A form of optical modulation at low pulse rates is reported in the case of surface plasmons excited by 1.55-mm photons in a thin gold foil. Several visible-photon energies are shown to be pulsed by the action of the infrared pulses, the effect being maximized when each visible beam also excites surface plasmons. The infrared surface plasmons are implicated as the primary cause of thermally indu...

In this paper we image the highly confined long range plasmons of a nanoscale metal stripe waveguide using quantum emitters. Plasmons were excited using a highly focused 633 nm laser beam and a specially designed grating structure to provide stronger incoupling to the desired mode. A homogeneous thin layer of quantum dots was used to image the near field intensity of the propagating plasmons on...

We provide electrical circuit descriptions for bulk plasmons, single surface plasmons, and parallel-plate plasmons. Simple circuits can reproduce the exactly known frequency versus wave-vector dispersion relations for all these cases, with reasonable accuracy. The circuit paradigm directly provides a characteristic wave-impedance, Zo, that is rarely discussed in the context of plasmonics. The c...