Aires Ferreira

Optomechanical entanglement between a movable mirror and a cavity field

In this paper we propose an experimental scheme to create and probe optomechanical entanglement between a light field and a mechanical oscillator. This is achieved using a bright laser field that resonates inside a cavity and couples to the position and momentum of a moving (micro)mirror.

A primer on surface plasmon-polaritons in graphene

We discuss the properties of surface plasmons-polaritons in graphene and describe four possible ways of coupling electromagnetic radiation in the terahertz (THz) spectral range to this type of surface waves: (i) the attenuated total reflection (ATR) method using a prism in the Otto configuration, (ii) graphene micro-ribbon arrays or monolayers with modulated conductivity, (iii) a metal stripe on top of the graphene layer, and (iv) graphene-based gratings. The text provides a number of original results along with their detailed derivation and discussion.

Efficient graphene-based photodetector with two cavities

We present an efficient graphene-based photodetector with two Fabri-Perot cavities. It is shown that the absorption can reach almost 100% around a given frequency, which is determined by the two-cavity lengths. It is also shown that hysteresis in the absorbance is possible, with the transmittance amplitude of the mirrors working as an external driving field. The role of non-linear contributions to the optical susceptibility of graphene is discussed.

Faraday effect in graphene enclosed in an optical cavity and the equation of motion method for the study of magneto-optical transport in solids

A.F. acknowledges FCT Grant No. SFRH/BPD/65600/2009. N.M.R.P. acknowledges Fundos FEDER, through the Programa Operacional Factores de Competitividade-COMPETE and by FCT under Project No. Past-C/FIS/UI0607/2011. A.H.C.N. acknowledges support from DOE Grant No. DE-FG02-08ER46512 and ONR Grant No. MURI N00014-09-1-1063.

Complete light absorption in graphene-metamaterial corrugated structures

We show that surface-plasmon polaritons excited in negative permittivity metamaterials having shallow periodic surface corrugation profiles can be explored to push the absorption of single and continuous sheets of graphene up to 100

Giant spin Hall effect in graphene grown by chemical vapour deposition

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A Unified Description of the DC Conductivity of Monolayer and Bilayer Graphene Based on Resonant Scatterers

. In the relaxation regime, the position of the plasmonic resonances of the hybrid system is determined by the plasma frequency of the metamaterial, allowing the frequency range for enhanced absorption to be set without the need of engineering graphene.

Exact solution for square-wave grating covered with graphene: surface plasmon-polaritons in the terahertz range

Advances in large-area graphene synthesis via chemical vapour deposition on metals like copper were instrumental in the demonstration of graphene-based novel, wafer-scale electronic circuits and proof-of-concept applications such as flexible touch panels. Here, we show that graphene grown by chemical vapour deposition on copper is equally promising for spintronics applications. In contrast to natural graphene, our experiments demonstrate that chemically synthesized graphene has a strong spin-orbit coupling as high as 20 meV giving rise to a giant spin Hall effect. The exceptionally large spin Hall angle ~0.2 provides an important step towards graphene-based spintronics devices within existing complementary metal-oxide-semiconductor technology. Our microscopic model shows that unavoidable residual copper adatom clusters act as local spin-orbit scatterers and, in the resonant scattering limit, induce transverse spin currents with enhanced skew-scattering contribution. Our findings are confirmed independently by introducing metallic adatoms-copper, silver and gold on exfoliated graphene samples.

Macroscopic thermal entanglement due to radiation pressure.

A.F. acknowledges FCT Grant No. SFRH/BPD/65600/2009. E.R.M. acknowledges partial financial support by NSF Grant No. DMR 1006230. A.H.C.N. acknowledges Grant No. DE-FG02-08ER46512. Discussions with A. K. Geim are acknowledged.

Extrinsic spin Hall effect induced by resonant skew scattering in graphene.

We provide an analytical solution to the problem of scattering of electromagnetic radiation by a square-wave grating with a flat graphene sheet on top. We show that for deep groves there is a strong plasmonic response, with light absorption in the graphene sheet reaching more than 45% due to the excitation of surface plasmon-polaritons. The case of a grating with a graphene sheet presenting an induced periodic modulation of the conductivity is also discussed.