Riccardo Sapienza

Semiconductor nanowire lasers

Nature Reviews Materials, Published online: 4 May 2016; doi:10.1038/natrevmats.2016.28

Recent research into semiconductor nanowire lasers has resulted in the advent of new materials, a broader wavelength selection and effective electrical pumping schemes, thereby bringing these nanoscale lasers much closer to application in fields like communications, computing, sensing and imaging.

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Author(s): Falko Diebel, Daniel Leykam, Sebastian Kroesen, Cornelia Denz, and Anton S. Desyatnikov

An array of optical waveguides bestows light waves with three spin-like states, which are observable in cone- and vortex-shaped diffraction patterns.

[Phys. Rev. Lett. 116, 183902] Published Wed May 04, 2016

Nanostructure-based plasmon-enhanced Raman spectroscopy for surface analysis of materials

Nature Reviews Materials, Published online: 26 April 2016; doi:10.1038/natrevmats.2016.21

Assisted by rationally designed novel plasmonic nanostructures, surface-enhanced Raman spectroscopy has presented a new generation of analytical tools (that is, tip-enhanced Raman spectroscopy and shell-isolated nanoparticle-enhanced Raman spectroscopy) with an extremely high surface sensitivity, spatial resolution and broad application for materials science and technology.

Riceviamo e pubblichiamo da Gherardo Vita, dottorando in Fisica al MIT

“Il governo si prepara a stanziare oltre 16 milioni di euro per un programma di inserimento nel mondo del lavoro di chi è in possesso di un PhD, ossia un dottorato di ricerca.

Nature Photonics 10, 291 (2016). doi:10.1038/nphoton.2016.81

Author: Brandon A. Kemp

Optical forces are increasingly relevant in nanoscale optical science and engineering, but optical momentum in materials is still not fully understood. It is now shown that microstructure details as well as macroscopic optical parameters are important in determining optical momentum.

According to the physicist Richard Feynman, a system is in equilibrium when “all the fast things have happened but the slow things have not” (1). This definition really applies to a system at steady state, which can either be in thermodynamic equilibrium or in a nonequilibrium steady state. Most systems in nature are not in equilibrium; they exchange fluxes of matter or energy with their surroundings or undergo chemical reactions. When the fast “things” have happened but the slow ones have not, such systems are in a nonequilibrium steady state. The properties of nonequilibrium steady states are currently under intense theoretical investigation, and their similarities and differences with thermodynamic equilibrium states are starting to emerge (2). On page 604 of this issue, Battle et al. (3) propose a new way of probing the nonequilibrium nature of an apparent steady state and demonstrate how such nonequilibrium dynamics can be identified. Authors: Jean-Francois Rupprecht, Jacques Prost

Physics: Cold coffee beans grind smaller

Nature 532, 7600 (2016). doi:10.1038/532417b

Roasted coffee beans that are ground when cold give smaller particles than those ground at room temperature, which could affect the drink's flavour.Christopher Hendon at the Massachusetts Institute of Technology in Cambridge and his colleagues ground coffee beans (grinding burr pictured) and measured

Nature Photonics 10, 285 (2016). doi:10.1038/nphoton.2016.88

Author: Noriaki Horiuchi

An AI learning to walk through a Doom-inspired maze by sight is one thing, but how can it handle live multiplayer mayhem? That's what the "Visual Doom AI" competition this September hopes to discover. The first set of matches are limited to a dozen 1...

Author: John Assad

Imaging techniques: A tale of two dipoles

Nature Reviews Materials, Published online: 19 April 2016; doi:10.1038/natrevmats.2016.27

From precision polymers to complex materials and systems

Nature Reviews Materials, Published online: 19 April 2016; doi:10.1038/natrevmats.2016.24

The polymer materials of the twenty-first century will be complex chemical systems that can respond and adapt to their environment. Such materials can be attained by synthesizing precision macromolecules with controlled architectures, and by mastering polymer interactions and self-organization.

Multibillion-euro innovation hub slammed by auditors

Nature 532, 7599 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.19753

Author: Quirin Schiermeier

Damning report blames failure to deliver on goals on management problems and funding issues.

Author(s): Q. Mermillod, T. Jakubczyk, V. Delmonte, A. Delga, E. Peinke, J.-M. Gérard, J. Claudon, and J. Kasprzak

We perform coherent nonlinear spectroscopy of individual excitons strongly confined in single InAs quantum dots (QDs). The retrieval of their intrinsically weak four-wave mixing (FWM) response is enabled by a one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded in bulk med…

[Phys. Rev. Lett. 116, 163903] Published Fri Apr 22, 2016

Slack is very useful team coordination software. It’s been such a help in my own lab, that I suspect that given a properly configured Slack account, I could simultaneously run GE, Google, Intel, and the US Federal Government.

It’s easy to dismiss Slack. To a large extent, it’s basically a bunch of chat rooms. I wasn’t interested in it at first, when my marketing executive sister first told me about it (around 2013, shortly after it was first released). She liked it for coordinating her team. At the time, my lab was small, and I didn’t need another channel of communication. But recently I’ve taken it on, and it has been an exceptionally positive thing for my lab.

I needed to push out several papers in a short period of time, and emailing people was clumsy and slow. Slack was perfect. I started using it then and it was transformative for that little bit of last minute dotting i’s and crossing t’s. We could exchange figure files, images, data, comments, etc. and it was all categorized by project, and had a nice timeline/history layout for browsing back through it. It’s also nice to search-by-project, rather than searching my entire email archive. Slack made it so much better.

I can tell you a few reasons why Slack is useful, and I will below. But really, you should just try it yourself. It’s free to try. See if you find it useful. Maybe you will, maybe you won’t.

It’s basically a team communications platform. You can set up as many channels as you like, for example, one channel per project. Within each channel, you can exchange messages. In practice, they tend to be brief and text message-like, but they can be longer. You can also exchange images, files, links, etc.

I like it for several reasons:

Everyone can see what’s going on in lab.

All of the discussions, files, screenshots, etc. about a particular project are all in one place. So if I need to bring someone into a project, I don’t have to find the dozens of email threads about the project and forward them. I can just have the new person browse the history of the project’s channel.

The text message-like informality makes quick exchanges much easier. Email is a bit old fashioned and slow. It’s a bit formal, even (compared to other electronic communication, anyways). Chat/text messaging is more immediate and faster.

Comments are editable and can even be deleted, which is handy for typos and general garbage control. There is also the risk of destroying information, but that’s relatively small in practice, I think.

Slack easily integrates with other tools like Google Docs, Evernote, Dropbox, etc. Even PubMed links are automatically expanded with the paper title and other information.

They have software for desktop (Windows, OSX, Linux) and mobile (iOS, Android, Windows Phone).

Here are some basic rules I follow right now. I have no great basis for these, it’s just what seems to work now:

One Team for the lab, and separate Teams for external collaborations (I’m part of an IARPA project, and that’s in a different team). Billing is by team, so this makes billing for collaborations more straightforward. It also makes it clear when we’re sharing info outside of the lab.

Minimal use of private channels. It’s fine to use them when appropriate (e.g., notes on fellowship applications), but don’t default to them. For example, don’t send me data figures in a private channel.

We have some general channels (e.g., optical_design, headfixed_behavior), but we mostly try to use project-specific channels. Roughly speaking, one paper per channel, or at least one paper at a time per channel. We need to actively suppress the haphazard creation of new channels.

We have a channel called “papers” where everyone is free to dump whatever interesting paper they want to.

There’s a “purchasing” channel that my assistant uses to track down paperwork and deal with ordering. That has been handy. This channel and some of the others were started by people in my lab. They were wise choices. So I’m going to keep letting people start their own channels. I’m the only person who can invite people to the team, but as long as my team keeps doing a clean job of starting channels, I’ll let them do that.

Article

Sensors based on localized surface plasmon resonance suffer from low figures of merit. Here, the authors achieve high refractive index sensitivities and figures of merit by introducing a chiral shape and the idea of engineering the material dispersion function.

Nature Communications doi: 10.1038/ncomms11331

Authors: Hyeon-Ho Jeong, Andrew G. Mark, Mariana Alarcón-Correa, Insook Kim, Peter Oswald, Tung-Chun Lee, Peer Fischer

Author(s): Kun Ding, Guancong Ma, Meng Xiao, Z. Q. Zhang, and C. T. Chan

Understanding the physics in multiple-state open systems is critical in many fields of physics. A study of an ensemble of connected lossy cavities shows how eigenstates can coalesce to produce new higher-order singularities.

[Phys. Rev. X 6, 021007] Published Tue Apr 12, 2016

Optical interfaces for quantum emitters are a prerequisite for implementing quantum networks. Here, we couple single molecules to the guided modes of an optical nanofiber. The molecules are embedded within a crystal that provides photostability and, due to the inhomogeneous broadening, a means to spectrally address single molecules. Single molecules are excited and detected solely via the nanofiber interface without the requirement of additional optical access. In this way, we realize a fully fiber-integrated system that is scalable and may become a versatile constituent for quantum hybrid systems.

Article

Cold atomic ensembles have been considered suitable platforms to realize quantum memories, but their scalability is limited by the cooling apparatuses. Here, the authors show how room temperature atomic microcells can be used for discrete variable ensemble-based quantum information processing.

Nature Communications doi: 10.1038/ncomms11356

Authors: J. Borregaard, M. Zugenmaier, J. M. Petersen, H. Shen, G. Vasilakis, K. Jensen, E. S. Polzik, A. S. Sørensen

The Netherlands is using the European Union's rotating presidency, which it currently holds, to promote open-access (OA) to the scientific literature. A 2-day meeting held last week produced an Amsterdam Call to Action that included the ambition to make all new papers published in the European Union freely available by 2020. Carlos Moedas, the European commissioner for research and innovation, favors an ambitious approach as well, and a meeting of Europe's ministers of research, innovation, and industry may adopt ambitious targets next month. The Netherlands is an OA front-runner itself, although some are critical of the country's emphatic choice for Gold OA, in which authors pay publishers to make their papers freely available. Author: Martin Enserink

Exploring the quantum speed limit with computer games

Nature 532, 7598 (2016). doi:10.1038/nature17620

Authors: Jens Jakob W. H. Sørensen, Mads Kock Pedersen, Michael Munch, Pinja Haikka, Jesper Halkjær Jensen, Tilo Planke, Morten Ginnerup Andreasen, Miroslav Gajdacz, Klaus Mølmer, Andreas Lieberoth & Jacob F. Sherson

Humans routinely solve problems of immense computational complexity by intuitively forming simple, low-dimensional heuristic strategies. Citizen science (or crowd sourcing) is a way of exploiting this ability by presenting scientific research problems to non-experts. ‘Gamification’—the application of game elements in a non-game context—is an effective tool with which to enable citizen scientists to provide solutions to research problems. The citizen science games Foldit, EteRNA and EyeWire have been used successfully to study protein and RNA folding and neuron mapping, but so far gamification has not been applied to problems in quantum physics. Here we report on Quantum Moves, an online platform gamifying optimization problems in quantum physics. We show that human players are able to find solutions to difficult problems associated with the task of quantum computing. Players succeed where purely numerical optimization fails, and analyses of their solutions provide insights into the problem of optimization of a more profound and general nature. Using player strategies, we have thus developed a few-parameter heuristic optimization method that efficiently outperforms the most prominent established numerical methods. The numerical complexity associated with time-optimal solutions increases for shorter process durations. To understand this better, we produced a low-dimensional rendering of the optimization landscape. This rendering reveals why traditional optimization methods fail near the quantum speed limit (that is, the shortest process duration with perfect fidelity). Combined analyses of optimization landscapes and heuristic solution strategies may benefit wider classes of optimization problems in quantum physics and beyond.

Hovertext: Keep her out of direct sunlight and if she gets fussy give her a trebuchet.

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Today's News:

Two days ago, I went downstairs to check on our crying toddler. Turns out she left a wooden toy on the bottom step. Long story short, fractured my fifth metatarsal. Readers should notice no difference, except for my planned 6 weeks of jokes focusing exclusively on metatarsals.