The Standard Quantum Limit of Coherent Beam Combining

Coherent beam combining refers to the process of generating a bright output beam by merging independent input beams with locked relative phases. We report the first quantum mechanical noise limit calculations for coherent beam combining and compare our results to quantum-limited amplification. Our coherent beam combining scheme is based on an optical Fourier transformation which renders the scheme compatible with integrated optics. The scheme can be layed out for an arbitrary number of input beams and approaches the shot noise limit for a large number of inputs

Quantum squeezing of motion in a mechanical resonator

As a result of the quantum, wave-like nature of the physical world, a harmonic oscillator can never be completely at rest. Even in the quantum ground state, its position will always have fluctuations, called the zero-point motion. Although the zero-point fluctuations are unavoidable, they can be manipulated. In this work, using microwave frequency radiation pressure, we both prepare a micron-scale mechanical system in a state near the quantum ground state and then manipulate its thermal fluctuations to produce a stationary, quadrature-squeezed state. We deduce that the variance of one motional quadrature is 0.80 times the zero-point level, or 1 dB of sub-zero-point squeezing. This work is relevant to the quantum engineering of states of matter at large length scales, the study of decoherence of large quantum systems, and for the realization of ultra-sensitive sensing of force and motion

Implementation of ROSA radio occultation data handling into EUMETSAT and GRAS SAF processing

Within this contribution, outcomes from a GRAS - SAF Visiting Scientist activity focused on the analysis of ROSA data quality for their use in operational weather forecasting will be described and main results will be shown. The ROSA Radio Occultation instrument has been developed by Thales-Alenia-Space, Italy and was funded by the Italian Space Agency (ASI). Such instrument is actually flying on-board three opportunity missions: the Indian OCEANSAT-2, the Argentinean SAC-D and the Indian-French MEGATROPIQUES. Focus of this Visiting Scientist activity has primarily been the analysis of ROSA data from OCEANSAT-2.This activity was divided into two parts. In the first one, performed at EUMETSAT, ROSA data processing was implemented into the EUMETSAT YAROS processor. The required updates into such processing package were implemented in order to make it able to properly manage also ROSA raw observations. It has to be noted that this processor is the baseline for the operational next generation EUMETSAT Radio Occultation ground segment: any changes performed in the framework of YAROS can easily be transferred to the operational ground segment. The YAROS - EUMETSAT processor was then updated and adapted to work with the ROSA raw data, tracking frequencies and instrument database. Adaptation to open loop data, navigation bits acquisition and potentially ionospheric measurement will be performed in the next future. NetCDF-4 YAROS output files are phases, amplitudes, bending angles over impact parameter, along with all other required data. Robust bias and standard deviation of bending angles to ECMWF collocated data were the statistical indicators generated to evaluate the quality of the ROSA observations. The second part of the activity was the adaptation of the GRAS-SAF ROPP (Radio Occultation Processing Package) processor for ROSA data processing. This second part was performed at Danish Meteorological Institute and has been focused on bending angles, refractivity and higher level product generation and validation against ECMWF and co-located occultation profiles. For the first time, one month of ROSA data have been deeply analyzed by a state-of-the-art Radio Occultation processing software and results will be described in the framework of this contributio

Electrothermal flow in Dielectrophoresis of Single-Walled Carbon Nanotubes

We theoretically investigate the impact of the electrothermal flow on the dielectrophoretic separation of single-walled carbon nanotubes (SWNT). The electrothermal flow is observed to control the motions of semiconducting SWNTs in a sizeable domain near the electrodes under typical experimental conditions, therefore helping the dielectrophoretic force to attract semiconducting SWNTs in a broader range. Moreover, with the increase of the surfactant concentration, the electrothermal flow is enhanced, and with the change of frequency, the pattern of the electrothermal flow changes. It is shown that under some typical experimental conditions of dielectrophoresis separation of SWNTs, the electrothermal flow is a dominating factor in determining the motion of SWNTs.Comment: 5 pages, 4 figures, Submitted to PR

Collective dynamics in optomechanical arrays

The emerging field of optomechanics seeks to explore the interaction between nanomechanics and light. Recently, the exciting concept of optomechanical crystals has been introduced, where defects in photonic crystal structures are used to generate both localized optical and mechanical modes that interact with each other. Here we start exploring the collective dynamics of arrays consisting of many coupled optomechanical cells. We show that such "optomechanical arrays" can display synchronization and that they can be described by a modified Kuramoto model that allows to explain and predict most of the features that will be observable in future experiments.Comment: 6 pages, 5 figure

Radiative Heating Profiles over Ascension Island during the 2016 and 2017 Biomass Burning Seasons

Marine boundary layer clouds, including the transition from stratocumulus to cumulus, are poorly represented in numerical weather prediction and general circulation models. In many cases, the complex physical relationships between cloud morphology and the environmental conditions in which marine boundary layer clouds exist are not well understood. Such uncertainties arise in the presence of biomass burning carbonaceous aerosol, as is the case over the southeast Atlantic Ocean, where it is likely that the absorbing and heating properties of these aerosols modify the microphysical composition and macrophysical arrangement of marine stratocumulus and trade cumulus. The deployment of the Atmospheric Radiation Measurement Mobile Facility #1 (AMF1) in support of LASIC (Layered Atlantic Smoke Interactions with Clouds) provided a unique opportunity to observe thermodynamic, cloud and aerosol properties during two consecutive biomass burning seasons from July through October of 2016 and 2017 over Ascension Island (7.96 S, 14.35 W). These observations in conjunction with radiation transfer modeling were used to assess the impact of biomass burning carbonaceous aerosol plumes as they passed over the site.Thermodynamic profiles were generated using a combination of radiosonde data and thermodynamic profilers to provide high temporal resolution profiles of quantities that are important for cloud development, such as CAPE and CIN. Coincident Ka-band radar and lidar profiles were used to characterize the cloud and sub-cloud structure. The resulting thermodynamic and cloud profiles are used as input forcing for the Rapid Radiative Transfer Model (RRTM) to compute radiative heating profiles over the observation site. Idealized experiments using RRTM, with and without aerosols present, are used to assess the impacts of the absorbing aerosol on the heating rate profiles

Development and Evaluation of an Undergraduate Science Communication Module

This paper describes the design and evaluation of an undergraduate final year science communication module for the Science Faculty at the University of East Anglia. The module focuses specifically on science communication and aims to bring an understanding of how science is disseminated to the public. Students on the module are made aware of the models surrounding science communication and investigate how the science culture interfaces with the public. During the module they learn how to adapt science concepts for different audiences and how to talk confidently about science to a lay-audience. Student motivation for module choice centres on the acquisition of transferable skills and students develop these skills through designing, running and evaluating a public outreach event at a school or in a public area. These transferable skills acquired include communication, interaction with different organisations such as museums and science centres, developing understanding of both the needs of different audiences and the importance of time management. They also develop skills relating to self-reflection and how to use this as a tool for future self development. The majority of students completing the module go on to further study, either a PhD, MSc or teacher training. The module can be sustained in its present formed if capped at 40 students, however it is recognised that to increase cohort size, further investment of faculty time and resources would be required