Riccardo Sapienza

Mohammad Ramezani, Alexei Halpin, Antonio I. Fernández-Domínguez, Johannes Feist, Said Rahimzadeh-Kalaleh Rodriguez, Francisco J. Garcia-Vidal, Jaime Gómez Rivas
Metallic nanostructures provide a toolkit for the generation of coherent light below the diffraction limit. Plasmonic-based lasing relies on the population inversion of emitters (such as organic fluorophores) along with feedback provided by plasmonic resonances. In this regime, known as weak ... [Optica 4, 31-37 (2017)]

Author(s): Roxana Rezvani Naraghi and Aristide Dogariu

It has been a long time belief that, with increasing the scattering strength of multiple scattering media, the transport of light gradually slows down and, eventually, comes to a halt corresponding to a localized state. Here we present experimental evidence that different stages emerge in this evolu…

[Phys. Rev. Lett. 117, 263901] Published Wed Dec 21, 2016

Nature Materials 16, 35 (2017). doi:10.1038/nmat4767

Authors: Jean-Luc Brédas, Edward H. Sargent & Gregory D. Scholes

A fundamental manifestation of wave scattering in a disordered medium is the highly complex intensity pattern the waves acquire due to multi-path interference. Here we show that these intensity variations can be entirely suppressed by adding disorder-specific gain and loss components to the medium. The resulting constant-intensity (CI) waves in such non-Hermitian scattering landscapes are free of any backscattering and feature perfect transmission through the disorder. An experimental demonstration of these unique wave states is envisioned based on spatially modulated pump beams that can flexibly control the gain and loss components in an active medium.

An emitter in the vicinity of a metal nanostructure is quenched by its decay through non-radiative channels, leading to the belief in a zone of inactivity for emitters placed within $<$10nm of a plasmonic nanostructure. Here we demonstrate that in tightly-coupled plasmonic resonators forming nanocavities "quenching is quenched" due to plasmon mixing. Unlike isolated nanoparticles, plasmonic nanocavities show mode hybridization which massively enhances emitter excitation and decay via radiative channels. This creates ideal conditions for realizing single-molecule strong-coupling with plasmons, evident in dynamic Rabi-oscillations and experimentally confirmed by laterally dependent emitter placement through DNA-origami.

Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution—e.g., magnetic...

The transmission of a wave through a randomly chosen `pile of plates' typically decreases exponentially with the number of plates, a phenomenon closely related to Anderson localisation. In apparent contradiction we construct disordered planar permittivity profiles which are complex-valued (i.e. have reactive and dissipative properties) that appear to vary randomly with position, yet are one-way reflectionless for all angles of incidence and exhibit a transmission coefficient of unity. We contrast these complex-valued 'random' planar permittivity profiles with a family of real-valued, two-way reflectionless and perfectly transmitting disordered permittivity profiles that function only for a single angle of incidence and frequency.

Holographic free-electron light source

Nature Communications, Published online: 2 December 2016; doi:10.1038/ncomms13705

Controlling the generation of light in nano-scale systems is a challenging task and is of growing importance. Here, Li et al. propose a means of controlling the wavefront of light emanating from a single nano scale emitter by holographic principles using a plasmonic metasurface.

Nature Physics 12, 1085 (2016). doi:10.1038/nphys3977

Authors: Liesbeth Venema, Bart Verberck, Iulia Georgescu, Giacomo Prando, Elsa Couderc, Silvia Milana, Maria Maragkou, Lina Persechini, Giulia Pacchioni & Luke Fleet

Quasiparticles are an extremely useful concept that provides a more intuitive understanding of complex phenomena in many-body physics. As such, they appear in various contexts, linking ideas across different fields and supplying a common language.

Author(s): Timothy Sleasman, Mohammadreza F. Imani, Jonah N. Gollub, and David R. Smith

When coupled to a tuning mechanism, a disordered medium provides a powerful means for shaping electromagnetic waveforms. The authors leverage this functionality to conduct volumetric computational imaging: A deformed cavity is outfitted with tailored, irregular surfaces, and its microwave resonant modes are projected into an imaging domain to retrieve the scene’s spatial information. This approach could be applied to biomedical imaging, security screening, or wireless power transfer or telecommunications.

[Phys. Rev. Applied 6, 054019] Published Tue Nov 29, 2016

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Piled Higher & Deeper by Jorge Cham		www.phdcomics.com
title: "Academic Apps" - originally published 11/30/2016 For the latest news in PHD Comics, CLICK HERE!

In artificial neural networks, learning from data is a computationally demanding task in which a large number of connection weights are iteratively tuned through stochastic-gradient-based heuristic processes over a cost function. It is not well understood how learning occurs in these systems, in particular how they avoid getting trapped in...

Author(s): Pierre Colman, Per Lunnemann, Yi Yu, and Jesper Mørk

We present pump-probe measurements of an all-optical photonic crystal switch based on a nanocavity, resolving fast coherent temporal dynamics. The measurements demonstrate the importance of coherent effects typically neglected when considering nanocavity dynamics. In particular, we report the observ…

[Phys. Rev. Lett. 117, 233901] Published Tue Nov 29, 2016

Nature Photonics 10, 751 (2016). doi:10.1038/nphoton.2016.244

Author: Oliver Graydon