International audienceHeat can be exchanged between two surfaces through emission and absorption of thermal radiation. It has been predicted theoretically that for distances smaller than the peak wavelength of the blackbody spectrum, radiative heat transfer can be increased by the contribution of evanescent waves(1-8). This contribution can be viewed as energy tunnelling through the gap between the surfaces. Although these effects have already been observed(9-14), a detailed quantitative comparison between theory and experiments in the nanometre regime is still lacking. Here, we report an experimental setup that allows measurement of conductance for gaps varying between 30 nm and 2.5 mu m. Our measurements pave the way for the design of submicrometre nanoscale heaters that could be used for heat-assisted magnetic recording or heat-assisted lithography

We present a formulation of the nanoscale radiative heat transfer (RHT) using concepts of mesoscopic physics. We introduce the analog of the Sharvin conductance using the quantum of thermal conductance. The formalism provides a convenient framework to analyse the physics of RHT at the nanoscale. Finally, we propose a RHT experiment in the regime of quantized conductance.PACS numbers: 44.40.+a;73.23.-b It has been discovered in the late sixties that the RHT between two metallic parallel plates can be larger than predicted using the blackbody radiation form [1][2][3]. It is now known that this anomalous RHT is due to the contribution of evanescent waves and becomes significant when the distance separating the interfaces becomes smaller than the thermal wavelength λ th = c kBT where is Planck's constant, k B is Boltzmann's constant, c is the light velocity and T is the temperature. Using the framework of fluctuational electrodynamics [4], Polder and van Hove (PvH) were able to derive a general form of the RHT accounting for the optical properties of the media [5]. Since this seminal contribution, several reports have been published in the literature [6][7][8][9][10][11]. A quantum-mechanical derivation [12] has confirmed these results obtained within the framework of fluctuational electrodynamics. While the first papers considered metals, it has been realized that the RHT at the nanoscale can be further enhanced for dielectrics due to the contribution of surface phonon polaritons [13,14]. Recent reviews can be found in Refs. [15][16][17][18].The first attempts to measure a heat flux between metallic surfaces at room temperature and micrometric distances have proved to be inconclusive [19,20]. Experiments in the nanometric regime have clearly demonstrated the transfer enhancement [21,22]. Yet the lack of good control of the tip geometry did not allow quantitative comparison with theory. More recent experiments [23,24] are performed using silica taking advantage of the flux enhancement due to the resonant contribution of surface phonon polaritons. A good agreement between PvH theory and experiments has been reported [24].The purpose of this paper is to establish a link between the PvH form of the radiative heat flux and the formalism of transport in mesoscopic physics. It will help to develop a more physical understanding of the RHT at the nanoscale, which also clarifies how losses and non-local effects determine the maximal achievable heat flux [10]. Finally, we will show that this reformulation raises the prospect of observing quantized conductance for systems with sizes on the order of the thermal wavelength λ th .We start our discussion with the PvH form of the RHT. We consider a vacuum gap with width d separating two homogeneous half spaces labeled medium 1 and 2 [see Fig. 1 a)]. Then, the heat flux is [5,16] ( 1) where κ = (k x , k y ) and γ = k 2 0 − κ 2 are the parallel and normal wave vector, Θ(ω,is the mean energy of a harmonic oscillator, k 0 = ω/c, r 1,2 j are the usual Fresnel factors for s-or p-polar...

Keywords : surface plasmon polariton, unidirectional launcher and decoupler, plasmonic nanoantenna, diffraction gratings. ABSTRACT :Controlling the launching efficiencies and the directionality of surface plasmon polaritons (SPPs) and their decoupling to freely propagating light is a major goal for the development of plasmonic devices and systems.Here, we report on the design and experimental observation of a highly efficient unidirectional surface plasmon launcher composed of eleven subwavelength grooves, each with a distinct depth and width. Our observations show that, under normal illumination by a focused Gaussian beam, unidirectional SPP launching with an efficiency of at least 52% is achieved experimentally with a compact device of total length smaller than 8 µm. Reciprocally, we report that the same device can efficiently convert SPPs into a highly directive light beam emanating perpendicularly to the sample. 2 Introduction. As the demand for increasing speed and bandwidth of information processing rises, plasmonic

Surface plasma waves are collective oscillations of electrons that propagate along a metaldielectric interface [1]. In the last ten years, several groups have reproduced fundamental quantum optics experiments with surface plasmons. Observation of single-plasmon states [2,3], waveparticle duality [4,5], preservation of entanglement of photons in plasmon-assisted transmission [6][7][8], and more recently, two-plasmon interference have been reported [3,[9][10][11][12]. While losses are detrimental for the observation of squeezed states, they can be seen as a new degree of freedom in the design of plasmonic devices, thus revealing new quantum interference scenarios. Here we report the observation of two-plasmon quantum interference between two freely-propagating, non-guided SPPs interfering on lossy plasmonic beamsplitters. As discussed in Refs. [13,14], the presence of losses (scattering or absorption) relaxes constraints on the reflection and transmission factors of the beamsplitter, allowing the control of their relative phase. By using this degree of freedom, we are able to observe either coalescence or anticoalescence of identical plasmons.Two-particle interference, as a fundamental quantum feature, has been extensively studied with photons through the Hong-Ou-Mandel [15] dip and has been recently observed with guided plasmons in a large variety of plasmonic circuits. It showed the possibility to generate pairs of indistinguishable single plasmons (SPPs), which is an important requirement for potential quantum information applications [12,16,17]. Despite the presence of losses, these experiments have shown that quantum effects remain observable. In these experiments, the propagation paths were lossy, but the beamsplitters were non-lossy. The presence of losses on the beamsplitter was studied in Refs [13,14], where novel effects were predicted, including coherent absorption of single photon and N00N states [18,19]. In our work, we designed several plasmonic beamsplitters with different sets of reflection and transmission factors, that were used in a plasmonic version of the Hong-Ou-Mandel experiment. Depending on the samples, coincidences detection measurements lead either to a HOM-like dip, i.e. a signature of plasmon coalescence, or a HOM-peak, that we associate to plasmon anti-coalescence. Let first begin with a brief description of the experimental setup. It is based on a source of photon pairs. The photons of a given pair are sent to two photon-to-SPP converters, located at the surface of a plasmonic test platform. It has been shown recently that the photon arXiv:1610.07479v1 [quant-ph]

We investigate the opto-electronic properties of hexagonal boron nitride grown by high temperature plasma-assisted molecular beam epitaxy. We combine atomic force microscopy, spectroscopic ellipsometry, and photoluminescence spectroscopy in the deep ultraviolet to compare the quality of hexagonal boron nitride grown either on sapphire or highly oriented pyrolytic graphite. For both substrates, the emission spectra peak at 235 nm, indicating the high optical quality of hexagonal boron nitride grown by molecular beam epitaxy. The epilayers on highly oriented pyrolytic graphite demonstrate superior performance in the deep ultraviolet (down to 210 nm) compared to those on sapphire. These results reveal the potential of molecular beam epitaxy for the growth of hexagonal boron nitride on graphene, and more generally, for fabricating van der Waals heterostructures and devices by means of a scalable technology. LETTEROriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

We addressed the carrier dynamics in so-called G-centers in silicon (consisting of substitutional-interstitial carbon pairs interacting with interstitial silicons) obtained via ion implantation into a silicon-on-insulator wafer. For this point defect in silicon emitting in the telecommunication wavelength range, we unravel the recombination dynamics by time-resolved photoluminescence spectroscopy. More specifically, we performed detailed photoluminescence experiments as a function of excitation energy, incident power, irradiation fluence and temperature in order to study the impact of radiative and non-radiative recombination channels on the spectrum, yield and lifetime of G-centers. The sharp line emitting at 969 meV ($\sim$1280 nm) and the broad asymmetric sideband developing at lower energy share the same recombination dynamics as shown by time-resolved experiments performed selectively on each spectral component. This feature accounts for the common origin of the two emission bands which are unambiguously attributed to the zero-phonon line and to the corresponding phonon sideband. In the framework of the Huang-Rhys theory with non-perturbative calculations, we reach an estimation of 1.6$\pm$0.1 $\angstrom$ for the spatial extension of the electronic wave function in the G-center. The radiative recombination time measured at low temperature lies in the 6 ns-range. The estimation of both radiative and non-radiative recombination rates as a function of temperature further demonstrate a constant radiative lifetime. Finally, although G-centers are shallow levels in silicon, we find a value of the Debye-Waller factor comparable to deep levels in wide-bandgap materials. Our results point out the potential of G-centers as a solid-state light source to be integrated into opto-electronic devices within a common silicon platform

IMPORTANCE Rocuronium and succinylcholine are often used for rapid sequence intubation, although the comparative efficacy of these paralytic agents for achieving successful intubation in an emergency setting has not been evaluated in clinical trials. Succinylcholine use has been associated with several adverse events not reported with rocuronium.OBJECTIVE To assess the noninferiority of rocuronium vs succinylcholine for tracheal intubation in out-of-hospital emergency situations. DESIGN, SETTING AND PARTICIPANTS Multicenter, single-blind, noninferiority randomized clinical trial comparing rocuronium (1.2 mg/kg) with succinylcholine (1 mg/kg) for rapid sequence intubation in 1248 adult patients needing out-of-hospital tracheal intubation. Enrollment occurred from January 2014 to August 2016 in 17 French out-of-hospital emergency medical units. The date of final follow-up was August 31, 2016.INTERVENTIONS Patients were randomly assigned to undergo tracheal intubation facilitated by rocuronium (n = 624) or succinylcholine (n = 624). MAIN OUTCOMES AND MEASURESThe primary outcome was the intubation success rate on first attempt. A noninferiority margin of 7% was chosen. A per-protocol analysis was prespecified as the primary analysis.RESULTS Among 1248 patients who were randomized (mean age, 56 years; 501 [40.1%] women), 1230 (98.6%) completed the trial and 1226 (98.2%) were included in the per-protocol analysis. The number of patients with successful first-attempt intubation was 455 of 610 (74.6%) in the rocuronium group vs 489 of 616 (79.4%) in the succinylcholine group, with a between-group difference of −4.8% (1-sided 97.5% CI, −9% to ϱ), which did not meet criteria for noninferiority. The most common intubation-related adverse events were hypoxemia (55 of 610 patients [9.0%]) and hypotension (39 of 610 patients [6.4%]) in the rocuronium group and hypoxemia (61 of 616 [9.9%]) and hypotension (62 of 616 patients [10.1%]) in the succinylcholine group.CONCLUSIONS AND RELEVANCE Among patients undergoing endotracheal intubation in an out-of-hospital emergency setting, rocuronium, compared with succinylcholine, failed to demonstrate noninferiority with regard to first-attempt intubation success rate.

International audienceHeat transfer between two plates of polar materials at nanoscale distance is known to be enhanced by several orders of magnitude as compared with its far-field value. In this article, we derive accu- rate analytical expressions to quantitatively predict heat fluxes in the near-field. These analytical expressions reveal the physical mechanisms responsible for the enhancement. For two dielectric polar materials and for gaps smaller than 75nm at room temperature the heat transfer is dominated by the surface phonon polariton contribution. Between 75nm and 500 nm, the enhancement is mostly due to frustrated total internal reflection. The paper reports accurate analytical expressions for both contributions. Our analytical results highlight two differences between radiation flux at the nanoscale and in the far field: i)the heat flux spectrum depends on the gap distance, ii) the temperature dependence of the heat transfer coefficient deviates strongly from the T3 law valid for gray bodies in the far-fiel