Riccardo Sapienza

Business culture and dishonesty in the banking industry

Nature 516, 7529 (2014). doi:10.1038/nature13977

Authors: Alain Cohn, Ernst Fehr & Michel André Maréchal

Trust in others’ honesty is a key component of the long-term performance of firms, industries, and even whole countries. However, in recent years, numerous scandals involving fraud have undermined confidence in the financial industry. Contemporary commentators have attributed these scandals to the financial sector’s business culture, but no scientific evidence supports this claim. Here we show that employees of a large, international bank behave, on average, honestly in a control condition. However, when their professional identity as bank employees is rendered salient, a significant proportion of them become dishonest. This effect is specific to bank employees because control experiments with employees from other industries and with students show that they do not become more dishonest when their professional identity or bank-related items are rendered salient. Our results thus suggest that the prevailing business culture in the banking industry weakens and undermines the honesty norm, implying that measures to re-establish an honest culture are very important.

Boosting nonlinear frequency conversion in extremely confined volumes remains a key challenge in nano-optics, nanomedicine, photocatalysis, and background-free biosensing. To this aim, field enhancements in plasmonic nanostructures are often exploited to effectively compensate for the lack of phase-matching at the nanoscale. Second harmonic generation (SHG) is, however, strongly quenched by the high degree of symmetry in plasmonic materials at the atomic scale and in nanoantenna designs. Here, we devise a plasmonic nanoantenna lacking axial symmetry, which exhibits spatial and frequency mode overlap at both the excitation and the SHG wavelengths. The effective combination of these features in a single device allows obtaining unprecedented SHG conversion efficiency. Our results shed new light on the optimization of SHG at the nanoscale, paving the way to new classes of nanoscale coherent light sources and molecular sensing devices based on nonlinear plasmonic platforms.

Experiments explain why certain birds, beetles, and photonic glasses, which derive their colors from interference effects, can be blue but not red.

Published Wed Dec 03, 2014

Author(s): A. A. Fernández-Marín, J. A. Méndez-Bermúdez, J. Carbonell, F. Cervera, J. Sánchez-Dehesa, and V. A. Gopar

Experimental evidence demonstrating that anomalous localization of waves can be induced in a controllable manner is reported. A microwave waveguide with dielectric slabs randomly placed is used to confirm the presence of anomalous localization. If the random spacing between slabs follows a distribut…

[Phys. Rev. Lett. 113, 233901] Published Wed Dec 03, 2014

Author(s): Alessandro Attanasi, Andrea Cavagna, Lorenzo Del Castello, Irene Giardina, Stefania Melillo, Leonardo Parisi, Oliver Pohl, Bruno Rossaro, Edward Shen, Edmondo Silvestri, and Massimiliano Viale

The seemingly erratic motion of insects in a swarm exhibits the correlated behavior of particles near the critical point of a phase transition.

[Phys. Rev. Lett. 113, 238102] Published Mon Dec 01, 2014

The seemingly erratic motion of insects in a swarm exhibits the correlated behavior of particles near the critical point of a phase transition.

Published Mon Dec 01, 2014

We investigated experimentally the ray-wave correspondence in organic microlasers of various triangular shapes. Triangular billiards are of interest since they are the simplest cases of polygonal billiards and the existence and properties of periodic orbits in triangles are not yet fully understood. The microlasers with symmetric shapes that were investigated exhibited states localized on simple periodic orbits, and their lasing characteristics like spectra and far-field distributions could be well explained by the properties of the periodic orbits. Furthermore, asymmetric triangles that do not feature simple periodic orbits were studied. Their lasing properties were found to be more complicated and could not be explained by periodic orbits.

Piled Higher & Deeper by Jorge Cham		www.phdcomics.com
title: "How to read a Professor's Door" - originally published 11/28/2014 For the latest news in PHD Comics, CLICK HERE!

Nature Physics 10, 891 (2014). doi:10.1038/nphys3195

As the debate on immigration in the UK becomes increasingly visceral, British science risks being caught in the crossfire.

Nature Photonics 8, 937 (2014). doi:10.1038/nphoton.2014.249

Authors: Alireza Marandi, Zhe Wang, Kenta Takata, Robert L. Byer & Yoshihisa Yamamoto

Finding the ground states of the Ising Hamiltonian maps to various combinatorial optimization problems in biology, medicine, wireless communications, artificial intelligence and social network. So far, no efficient classical and quantum algorithm is known for these problems and intensive research is focused on creating physical systems—Ising machines—capable of finding the absolute or approximate ground states of the Ising Hamiltonian. Here, we report an Ising machine using a network of degenerate optical parametric oscillators (OPOs). Spins are represented with above-threshold binary phases of the OPOs and the Ising couplings are realized by mutual injections. The network is implemented in a single OPO ring cavity with multiple trains of femtosecond pulses and configurable mutual couplings, and operates at room temperature. We programmed a small non-deterministic polynomial time-hard problem on a 4-OPO Ising machine and in 1,000 runs no computational error was detected.

Nature Photonics 8, 883 (2014). doi:10.1038/nphoton.2014.292

Author: Claude Fabre

A network of optical parametric oscillators has been harnessed to find solutions to a complex problem in statistical physics that is difficult to solve using numerical computing algorithms.

Open access is tiring out peer reviewers

Nature 515, 7528 (2014). http://www.nature.com/doifinder/10.1038/515467a

Author: Martijn Arns

As numbers of published articles rise, the scholarly review system must adapt to avoid unmanageable burdens and slipping standards, says Martijn Arns.

Publishing: The peer-review scam

Nature 515, 7528 (2014). http://www.nature.com/doifinder/10.1038/515480a

Authors: Cat Ferguson, Adam Marcus & Ivan Oransky

When a handful of authors were caught reviewing their own papers, it exposed weaknesses in modern publishing systems. Editors are trying to plug the holes.

George McNamara recently posted a comment on spectra, which referenced this online app which is handy.

We use time-domain numerical simulations of a two-dimensional (2D) scattering system to study the interaction of a collection of emitters resonantly coupled to an Anderson-localized mode. For a small electric field intensity, we observe the strong coupling between the emitters and the mode, which is characterized by linear Rabi oscillations. Remarkably, a larger intensity induces non-linear interaction between the emitters and the mode, referred to as the dynamical Stark effect, resulting in non-linear Rabi oscillations. The transition between both regimes is observed and an analytical model is proposed which accurately describes our numerical observations.

Controlling photon emission by single quantum emitters with nanostructures is crucial for scalable on-chip quantum information processing. Nowadays nanoresonators can affect the lifetime of emitters and ultimately induce strong coupling between the emitters and the light field, while nanoantennas can control the directionality of the emission. Expanding this control to the manipulation of the emission of orbital angular momentum-changing transitions would enable coupling between long-lived solid-state qubits and flying qubits. As these transitions are associated with circular rather than linear dipoles, such control requires detailed knowledge of the spatially dependent interaction of a complex dipole with highly structured optical eigenstates containing local helicity. Using a classical analogue, we experimentally map the coupling of circular dipoles to photonic modes in a model structure, a photonic crystal waveguide. We show that depending on the local helicity the dipoles can be made to couple to modes either propagating to the left or to the right. The maps are in excellent agreement with calculations. Our measurements, therefore, demonstrate the coupling of spin to photonic pathway with near-unity (0.8 $\pm$ 0.1) efficiency.

In this paper we report on numerical study of plasmonic nanoparticle chains with long-range dipole-dipole interaction. We have shown that introduction of positional disorder gives a peak in the density of resonant states (DOS) at the frequency of individual nanoparticle resonance. This peak is referred to Dyson singularity in one-dimensional disordered structures [Dyson F., 1953] and, according to our calculations, governs the spectral properties of local DOS. This provides disorder-induced Purcell enhancement that can found its applications in random lasers and for SERS spectroscopy. We stress that this effect relates not only to plasmonic nanoparticles but to an arbitrary chain of nanoparticles or atoms with resonant polarizabilities.

An automated analysis of the words in 117 years worth of the Physical Review selects scientific memes—significant ideas that emerge and spread through the literature.

Published Fri Nov 21, 2014

Author(s): L. Gil and G. L. Lippi

For many years, the apparent absence of a phase instability has characterized lasers as peculiar nonlinear oscillators. We show that this unusual feature is solely due to the approximations used in writing the standard models. A new, careful derivation of the fundamental equations, based on codimens...

[Phys. Rev. Lett. 113, 213902] Published Fri Nov 21, 2014

Article

Imaging through a single optical fibre offers attractive possibilities in applications such as micro-endoscopy or remote sensing. Using spread-spectrum encoding, Barankov and Mertz demonstrate two-dimensional imaging of self-luminous objects with high throughput, in theory independent of pixel number.

Nature Communications doi: 10.1038/ncomms6581

Authors: Roman Barankov, Jerome Mertz

Yulu Chen, Jason A. Newman, Kevin J. Webb
We present a family of circular Bessel probability density functions that are capable of describing the intensity, amplitude, and field statistics of waves in any random medium, with only the assumption of circularity. The well-known zero-mean circular Gaussian statistics break down in the Anderson ... [J. Opt. Soc. Am. A 31, 2744-2752 (2014)]

Yesterday I came across this video series, put up by "EngineerGuy" Bill Hammack.   It shows a mechanical analog computer originally designed by Michelson for building up Fourier series (sums of sinusoids) of up to twenty integer multiples of a fundamental frequency.   Moreover, you could use this machine to go backwards, and mechanically do Fourier decomposition of periodic waveforms.  It's really wonderful.  I would love to have one to use as a teaching tool, and I'm sure some enterprising person will figure out how to 3d print all the relevant parts (except the springs and cables), or perhaps build one out of Lego. 

I also wanted to point out Hammack's other videos.  This is great outreach - really accessible, clear, well-produced content.

That the speed of light in free space is constant is a cornerstone of modern physics. However, light beams have finite transverse size, which leads to a modification of their wavevectors resulting in a change to their phase and group velocities. We study the group velocity of single photons by measuring a change in their arrival time that results from changing the beam's transverse spatial structure. Using time-correlated photon pairs we show a reduction of the group velocity of photons in both a Bessel beam and photons in a focused Gaussian beam. In both cases, the delay is several microns over a propagation distance of the order of 1 m. Our work highlights that, even in free space, the invariance of the speed of light only applies to plane waves. Introducing spatial structure to an optical beam, even for a single photon, reduces the group velocity of the light by a readily measurable amount.

Author(s): Robert Dall, Michael D. Fraser, Anton S. Desyatnikov, Guangyao Li, Sebastian Brodbeck, Martin Kamp, Christian Schneider, Sven Höfling, and Elena A. Ostrovskaya

A spiral pattern of light imparts angular momentum to a quantum condensate in a semiconductor.

[Phys. Rev. Lett. 113, 200404] Published Wed Nov 12, 2014

We study arrays of plasmonic nanoparticles combined with quantum emitters, quantum plasmonic lattices, as a platform for room temperature studies of quantum many-body physics. We outline a theory to describe surface plasmon polariton distributions when they are coupled to externally pumped molecules. The possibility of tailoring the dispersion in plasmonic lattices allows realization of a variety of distributions, including the Bose-Einstein distribution as in photon condensation. We show that the presence of losses can relax some of the standard dimensionality restrictions for condensation.