GHz bandwidth electro-optics of a single self-assembled quantum dot in a charge-tunable device

The response of a single InGaAs quantum dot, embedded in a miniaturized charge-tunable device, to an applied GHz bandwidth electrical pulse is investigated via its optical response. Quantum dot response times of 1.0 \pm 0.1 ns are characterized via several different measurement techniques, demonstrating GHz bandwidth electrical control. Furthermore a novel optical detection technique based on resonant electron-hole pair generation in the hybridization region is used to map fully the voltage pulse experienced by the quantum dot, showing in this case a simple exponential rise.Comment: 7 pages, 4 figure

Estimation of fluorescence lifetimes via rotational invariance techniques

Estimation of signal parameters via rotational invariance techniques is a classical algorithm widely used in array signal processing for direction-of-arrival estimation of emitters. Inspired by this method, a new signal model and a new fluorescence lifetime estimation via rotational invariance techniques (FLERIT) were developed for multi-exponential fluorescence lifetime imaging (FLIM) experiments. The FLERIT only requires a few time bins of a histogram generated by a time-correlated single photon counting FLIM system, greatly reducing the data throughput from the imager to the signal processing units. As a non-iterative method, the FLERIT does not require initial conditions, prior information nor model selection that are usually required by widely used traditional fitting methods, including nonlinear least square methods or maximum likelihood methods. Moreover, its simplicity means it is suitable for implementations in embedded systems for real-time applications. FLERIT was tested on synthesized and experimental fluorescent cell data showing the potentials to be widely applied in FLIM data analysis

Ultracold collision properties of metastable alkaline-earth atoms

Ultra-cold collisions of spin-polarized 24Mg,40Ca, and 88Sr in the metastable 3P2 excited state are investigated. We calculate the long-range interaction potentials and estimate the scattering length and the collisional loss rate as a function of magnetic field. The estimates are based on molecular potentials between 3P2 alkaline-earth atoms obtained from ab initio atomic and molecular structure calculations. The scattering lengths show resonance behavior due to the appearance of a molecular bound state in a purely long-range interaction potential and are positive for magnetic fields below 50 mT. A loss-rate model shows that losses should be smallest near zero magnetic field and for fields slightly larger than the resonance field, where the scattering length is also positive.Comment: 4 pages, 4 figure

Nanometric depth resolution from multi-focal images in microscopy

We describe a method for tracking the position of small features in three dimensions from images recorded on a standard microscope with an inexpensive attachment between the microscope and the camera. The depth-measurement accuracy of this method is tested experimentally on a wide-field, inverted microscope and is shown to give approximately 8 nm depth resolution, over a specimen depth of approximately 6 µm, when using a 12-bit charge-coupled device (CCD) camera and very bright but unresolved particles. To assess low-flux limitations a theoretical model is used to derive an analytical expression for the minimum variance bound. The approximations used in the analytical treatment are tested using numerical simulations. It is concluded that approximately 14 nm depth resolution is achievable with flux levels available when tracking fluorescent sources in three dimensions in live-cell biology and that the method is suitable for three-dimensional photo-activated localization microscopy resolution. Sub-nanometre resolution could be achieved with photon-counting techniques at high flux levels

Redistributed manufacturing in healthcare: Creating new value through disruptive innovation

The RiHN White Paper is the first serious attempt to gather expertise and to explore applications in promising areas of healthcare that could benefit from RDM and covers early-stage user needs, challenges and priorities. The UK has an opportunity to lead in this area and RiHN has identified an extensive number of areas for fruitful R&D, crossing production technology, infrastructure, business and organisations. The paper serves as a foundation for discussing future technological roadmaps and engaging the wider community and stakeholders, as well as policy makers, in addressing the potential impact of RDM.The RiHN White Paper is of particular value to policy makers and funders seeking to specify action and to direct attention where it is needed. The White Paper is also useful for the research community, to support their proposals with credible research propositions and to show where collaboration with industry and the public sector will deliver the most benefits.In order to seize the opportunities presented by RDM RiHN proposes a bold new agenda that incorporates a whole healthcare system view of future implementation pathways and wider transformation implications. The priority areas for Future R&D can be summarised as follows: throughAutomated production platform technologies and supporting manufacturing infrastructuresAdvances in analytics and metrologyNew regulatory frameworks and governance pathwaysNew frameworks for business model and organisational transformationThe time to take action is now. Technologies are developing that have the potential to disrupt traditional healthcare pathways and offer therapies tailored to individual needs and physiological characteristics. The challenge is seizing this opportunity and make the UK a world leader in RDM