126 research outputs found

    A Multi-Channel Low-Power System-on-Chip for in Vivo Recording and Wireless Transmission of Neural Spikes

    Get PDF
    This paper reports a multi-channel neural spike recording system-on-chip with digital data compression and wireless telemetry. The circuit consists of 16 amplifiers, an analog time-division multiplexer, a single 8 bit analog-to-digital converter, a digital signal compression unit and a wireless transmitter. Although only 16 amplifiers are integrated in our current die version, the whole system is designed to work with 64, demonstrating the feasibility of a digital processing and narrowband wireless transmission of 64 neural recording channels. Compression of the raw data is achieved by detecting the action potentials (APs) and storing 20 samples for each spike waveform. This compression method retains sufficiently high data quality to allow for single neuron identification (spike sorting). The 400 MHz transmitter employs a Manchester-Coded Frequency Shift Keying (MC-FSK) modulator with low modulation index. In this way, a 1.25 Mbit/s data rate is delivered within a limited band of about 3 MHz. The chip is realized in a 0.35 um AMS CMOS process featuring a 3 V power supply with an area of 3.1x 2.7 mm2. The achieved transmission range is over 10 m with an overall power consumption for 64 channels of 17.2 mW. This figure translates into a power budget of 269uW per channel, in line with published results but allowing a larger transmission distance and more efficient bandwidth occupation of the wireless link. The integrated circuit was mounted on a small and light board to be used during neuroscience experiments with freely-behaving rats. Powered by 2 AAA batteries, the system can continuously work for more than 100 hours allowing for long-lasting neural spike recordings

    GHz QKD at telecom wavelengths using up-conversion detectors

    Full text link
    We have developed a hybrid single photon detection scheme for telecom wavelengths based on nonlinear sum-frequency generation and silicon single-photon avalanche diodes (SPADs). The SPAD devices employed have been designed to have very narrow temporal response, i.e. low jitter, which we can exploit for increasing the allowable bit rate for quantum key distribution. The wavelength conversion is obtained using periodically poled Lithium niobate waveguides (W/Gs). The inherently high efficiency of these W/Gs allows us to use a continuous wave laser to seed the nonlinear conversion so as to have a continuous detection scheme. We also present a 1.27GHz qubit repetition rate, one-way phase encoding, quantum key distribution experiment operating at telecom wavelengths that takes advantage of this detection scheme. The proof of principle experiment shows a system capable of MHz raw count rates with a QBER less than 2% and estimated secure key rates greater than 100 kbit/s over 25 km.Comment: 12 pages, 7 figure

    Quantum Cryptography

    Get PDF
    Quantum cryptography could well be the first application of quantum mechanics at the individual quanta level. The very fast progress in both theory and experiments over the recent years are reviewed, with emphasis on open questions and technological issues.Comment: 55 pages, 32 figures; to appear in Reviews of Modern Physic

    Long-distance Bell-type tests using energy-time entangled photons

    Full text link
    Long-distance Bell-type experiments are presented. The different experimental challenges and their solutions in order to maintain the strong quantum correlations between energy-time entangled photons over more than 10 km are reported and the results analyzed from the point of view of tests of fundamental physics as well as from the more applied side of quantum communication, specially quantum key distribution. Tests using more than one analyzer on each side are also presented.Comment: 22 pages including 7 figures and 5 table

    Application of Silicon Photomultipliers to Positron Emission Tomography

    Get PDF
    Historically, positron emission tomography (PET) systems have been based on scintillation crystals coupled to photomultipliers tubes (PMTs). However, the limited quantum efficiency, bulkiness, and relatively high cost per unit surface area of PMTs, along with the growth of new applications for PET, offers opportunities for other photodetectors. Among these, small-animal scanners, hybrid PET/MRI systems, and incorporation of time-of-flight information are of particular interest and require low-cost, compact, fast, and magnetic field compatible photodetectors. With high quantum efficiency and compact structure, avalanche photodiodes (APDs) overcome several of the drawbacks of PMTs, but this is offset by degraded signal-to-noise and timing properties. Silicon photomultipliers (SiPMs) offer an alternative solution, combining many of the advantages of PMTs and APDs. They have high gain, excellent timing properties and are insensitive to magnetic fields. At the present time, SiPM technology is rapidly developing and therefore an investigation into optimal design and operating conditions is underway together with detailed characterization of SiPM-based PET detectors. Published data are extremely promising and show good energy and timing resolution, as well as the ability to decode small scintillator arrays. SiPMs clearly have the potential to be the photodetector of choice for some, or even perhaps most, PET systems

    The health determinants in young children: Testing a new surveillance system in Italy

    Get PDF
    In recent years, the scientific community has stressed the need to invest in the first 1,000 days of life - the time spanning between conception and the 2nd birthday - because it is during this period that the foundations of health are laid and whose effects will be present throughout the life and may influence the next generation. Taking this into account, in 2013 the National Centre for Disease Prevention and Control (CCM) of the Italian Ministry of Health promoted and financed a project to test a surveillance system of the main determinants of health concerning the child between the conception period and the 2nd years of life which are included in the National Programme “GenitoriPiù”: folic acid before and during pregnancy, abstention from tobacco and alcohol during pregnancy and lactation, breastfeeding, infant sleep position, vaccination attitude, and early reading. The Project, started in January 2014 and ended in August 2016, has piloted the design, testing, and evaluation of the surveillance system with the view to national extension and the repeatability over time. The surveillance system has been designed to collect data through a questionnaire compiled by mothers in vaccination centres, in order to produce indicators which will enable territorial and intertempo-ral comparisons to be made. The project has shown the feasibility of this system, identifying favourable conditions and possible difficulties, and its ability to collect important information on children's health

    No dead-space optical time-domain reflectometer

    No full text
    corecore