Quantum key distribution over multicore fiber

We present the first quantum key distribution (QKD) experiment over multicore fiber. With space division multiplexing, we demonstrate that weak QKD signals can coexist with classical data signals launched at full power in a 53 km 7-core fiber, while showing negligible degradation in performance. Based on a characterization of intercore crosstalk, we perform additional simulations highlighting that classical data bandwidths beyond 1Tb/s can be supported with high speed QKD on the same fiber.S.J.K. acknowledges support from the EPSRC CDT in Photonic Systems Development

An in-plane photoelectric effect in two-dimensional electron systems for terahertz detection

Many mid- and far-infrared semiconductor photodetectors rely on a photonic response, when the photon energy is large enough to excite and extract electrons due to optical transitions. Toward the terahertz range with photon energies of a few milli–electron volts, classical mechanisms are used instead. This is the case in two-dimensional electron systems, where terahertz detection is dominated by plasmonic mixing and by scattering-based thermal phenomena. Here, we report on the observation of a quantum, collision-free phenomenon that yields a giant photoresponse at terahertz frequencies (1.9 THz), more than 10-fold as large as expected from plasmonic mixing. We artificially create an electrically tunable potential step within a degenerate two-dimensional electron gas. When exposed to terahertz radiation, electrons absorb photons and generate a large photocurrent under zero source-drain bias. The observed phenomenon, which we call the “in-plane photoelectric effect,” provides an opportunity for efficient direct detection across the entire terahertz range.George and Lilian Schiff Studentship, Schiff Foundation, University of Cambridge Honorary Vice-Chancellor’s Award, Cambridge Trust, University of Cambridg

Graphene based plasmonic terahertz amplitude modulator operating above 100 MHz

The terahertz (THz) region of the electromagnetic spectrum holds great potential in many fields of study, from spectroscopy to biomedical imaging, remote gas sensing, and high speed communication. To fully exploit this potential, fast optoelectronic devices such as amplitude and phase modulators must be developed. In this work, we present a room temperature external THz amplitude modulator based on plasmonic bow-tie antenna arrays with graphene. By applying a modulating bias to a back gate electrode, the conductivity of graphene is changed, which modifies the reflection characteristics of the incoming THz radiation. The broadband response of the device was characterized by using THz time-domain spectroscopy, and the modulation characteristics such as the modulation depth and cut-off frequency were investigated with a 2.0 THz single frequency emission quantum cascade laser. An optical modulation cut-off frequency of 105 ± 15 MHz is reported. The results agree well with a lumped element circuit model developed to describe the device.R.D., Y.R., H.E.B., and D.A.R. acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant No. EP/J017671/1, Coherent Terahertz Systems). P.B.-W. and S.H. acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant Nos. EP/K016636/1, GRAPHTED). H.L. and J.A.Z. acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant No. EP/L019922/1)

Active Terahertz Modulator and Slow Light Metamaterial Devices with Hybrid Graphene-Superconductor Photonic Integrated Circuits.

Metamaterial photonic integrated circuits with arrays of hybrid graphene-superconductor coupled split-ring resonators (SRR) capable of modulating and slowing down terahertz (THz) light are introduced and proposed. The hybrid device's optical responses, such as electromagnetic-induced transparency (EIT) and group delay, can be modulated in several ways. First, it is modulated electrically by changing the conductivity and carrier concentrations in graphene. Alternatively, the optical response can be modified by acting on the device temperature sensitivity by switching Nb from a lossy normal phase to a low-loss quantum mechanical phase below the transition temperature (Tc) of Nb. Maximum modulation depths of 57.3% and 97.61% are achieved for EIT and group delay at the THz transmission window, respectively. A comparison is carried out between the Nb-graphene-Nb coupled SRR-based devices with those of Au-graphene-Au SRRs, and significant enhancements of the THz transmission, group delay, and EIT responses are observed when Nb is in the quantum mechanical phase. Such hybrid devices with their reasonably large and tunable slow light bandwidth pave the way for the realization of active optoelectronic modulators, filters, phase shifters, and slow light devices for applications in chip-scale future communication and computation systems

Community first responders and responder schemes in the United Kingdom: systematic scoping review

Background: Community First Responder (CFR) schemes support lay people to respond to medical emergencies, working closely with ambulance services. They operate widely in the UK. There has been no previous review of UK literature on these schemes. This is the first systematic scoping review of UK literature on CFR schemes, which identifies the reasons for becoming a CFR, requirements for training and feedback and confusion between the CFR role and that of ambulance service staff. This study also reveals gaps in the evidence base for CFR schemes. Methods: We conducted a systematic scoping review of the published literature, in the English language from 2000 onwards using specific search terms in six databases. Narrative synthesis was used to analyse article content. Results: Nine articles remained from the initial search of 15,969 articles after removing duplicates, title and abstract and then full text review. People were motivated to become CFRs through an altruistic desire to help others. They generally felt rewarded by their work but recognised that the help they provided was limited by their training compared with ambulance staff. There were concerns about the possible emotional impact on CFRs responding to incidents. CFRs felt that better feedback would enhance their learning. Ongoing training and support were viewed as essential to enable CFRs to progress. They perceived that public recognition of the CFR role was low, patients sometimes confusing them with ambulance staff. Relationships with the ambulance service were sometimes ambivalent due to confusion over roles. There was support for local autonomy of CFR schemes but with greater sharing of best practice. Discussion: Most studies dated from 2005 and were descriptive rather than analytical. In the UK and Australia CFRs are usually lay volunteers equipped with basic skills for responding to medical emergencies, whereas in the US they include other emergency staff as well as lay people. Conclusion: Opportunities for future research include exploring experiences and perceptions of patients who have been treated by CFRs and other stakeholders, while also evaluating the effectiveness and costs of CFR schemes

Metamaterial/graphene active terahertz modulators

Within the last years there has been a tremendous thrust into research and technology in the THz spectral region (broadly defined as 0.1-10 THz) mainly driven by the unique potential where this radiation finds applications in, such as imaging, spectroscopy and communication. In all these fields a fast, integrated and versatile platform for modulating light is required. Metamaterial/graphene devices fulfill all these requirements as their subwavelength nature lends itself naturally to strong light-matter interaction, and therefore highly efficient and miniaturized devices. Graphene's unique properties, e.g. the large carrier concentration modulation, provide a large degree of compatibility with several architectures which can be exploited in a range of modulation or detection schemes. Finally, metamaterial/graphene devices realize a fast, versatile platform, which can be easily scaled to other frequencies, and adapted into amplitude, frequency, polarization and phase modulators, as well as integrated detectors, for the next generation of wireless-communication

Basic science232. Certolizumab pegol prevents pro-inflammatory alterations in endothelial cell function

Background: Cardiovascular disease is a major comorbidity of rheumatoid arthritis (RA) and a leading cause of death. Chronic systemic inflammation involving tumour necrosis factor alpha (TNF) could contribute to endothelial activation and atherogenesis. A number of anti-TNF therapies are in current use for the treatment of RA, including certolizumab pegol (CZP), (Cimzia ®; UCB, Belgium). Anti-TNF therapy has been associated with reduced clinical cardiovascular disease risk and ameliorated vascular function in RA patients. However, the specific effects of TNF inhibitors on endothelial cell function are largely unknown. Our aim was to investigate the mechanisms underpinning CZP effects on TNF-activated human endothelial cells. Methods: Human aortic endothelial cells (HAoECs) were cultured in vitro and exposed to a) TNF alone, b) TNF plus CZP, or c) neither agent. Microarray analysis was used to examine the transcriptional profile of cells treated for 6 hrs and quantitative polymerase chain reaction (qPCR) analysed gene expression at 1, 3, 6 and 24 hrs. NF-κB localization and IκB degradation were investigated using immunocytochemistry, high content analysis and western blotting. Flow cytometry was conducted to detect microparticle release from HAoECs. Results: Transcriptional profiling revealed that while TNF alone had strong effects on endothelial gene expression, TNF and CZP in combination produced a global gene expression pattern similar to untreated control. The two most highly up-regulated genes in response to TNF treatment were adhesion molecules E-selectin and VCAM-1 (q 0.2 compared to control; p > 0.05 compared to TNF alone). The NF-κB pathway was confirmed as a downstream target of TNF-induced HAoEC activation, via nuclear translocation of NF-κB and degradation of IκB, effects which were abolished by treatment with CZP. In addition, flow cytometry detected an increased production of endothelial microparticles in TNF-activated HAoECs, which was prevented by treatment with CZP. Conclusions: We have found at a cellular level that a clinically available TNF inhibitor, CZP reduces the expression of adhesion molecule expression, and prevents TNF-induced activation of the NF-κB pathway. Furthermore, CZP prevents the production of microparticles by activated endothelial cells. This could be central to the prevention of inflammatory environments underlying these conditions and measurement of microparticles has potential as a novel prognostic marker for future cardiovascular events in this patient group. Disclosure statement: Y.A. received a research grant from UCB. I.B. received a research grant from UCB. S.H. received a research grant from UCB. All other authors have declared no conflicts of interes