High Purcell factor generation of indistinguishable on-chip single photons

On-chip single-photon sources are key components for integrated photonic quantum technologies. Semiconductor quantum dots can exhibit near-ideal single-photon emission, but this can be significantly degraded in on-chip geometries owing to nearby etched surfaces. A long-proposed solution to improve the indistinguishablility is to use the Purcell effect to reduce the radiative lifetime. However, until now only modest Purcell enhancements have been observed. Here we use pulsed resonant excitation to eliminate slow relaxation paths, revealing a highly Purcell-shortened radiative lifetime (22.7 ps) in a waveguide-coupled quantum dot–photonic crystal cavity system. This leads to near-lifetime-limited single-photon emission that retains high indistinguishablility (93.9%) on a timescale in which 20 photons may be emitted. Nearly background-free pulsed resonance fluorescence is achieved under π-pulse excitation, enabling demonstration of an on-chip, on-demand single-photon source with very high potential repetition rates

Arctic Observatory FRAM - a modern vision of integrated underwater infrastructure in the polar environment

The Arctic Observatory FRAM (FRontiers in Arctic Marine Monitoring) targets a modern vision of integrated underwater infrastructure in the polar environment. Since 2014 this modular observatory is being build up in Fram-Strait and the Central Arctic by the Alfred Wegner Institute for Polar and Marine Research (AWI) to become a major research infrastructure of the Earth and Environment research field of the Helmholtz Association. FRAM enhances sustainable knowledge of the remote and harsh Arctic environment for science, society and maritime economy as it enables truly year round multidisciplinary observations from sea ice to the deep sea. Cutting edge mobile and fixed sensor platforms and technologies like e.g. ROV’s, AUV’s, under water robotics, and moorings are being (further) developed and used in combination with ship based instruments to record various essential ocean variables to improve our understanding of the Arctic Ocean, it’s essential processes, and how they are being impacted by continued warming and decreasing sea ice extend. Field data are being cross validated by satellite observations and used to improve model simulations. Data will be made freely available to the public via the AWI data portal

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016