Detection-Loophole-Free Test of Quantum Nonlocality, and Applications

We present a source of entangled photons that violates a Bell inequality free of the "fair-sampling" assumption, by over 7 standard deviations. This violation is the first experiment with photons to close the detection loophole, and we demonstrate enough "efficiency" overhead to eventually perform a fully loophole-free test of local realism. The entanglement quality is verified by maximally violating additional Bell tests, testing the upper limit of quantum correlations. Finally, we use the source to generate secure private quantum random numbers at rates over 4 orders of magnitude beyond previous experiments.Comment: Main text: 5 pages, 2 figures, 1 table. Supplementary Information: 7 pages, 2 figure

Immersive interconnected virtual and augmented reality : a 5G and IoT perspective

Despite remarkable advances, current augmented and virtual reality (AR/VR) applications are a largely individual and local experience. Interconnected AR/VR, where participants can virtually interact across vast distances, remains a distant dream. The great barrier that stands between current technology and such applications is the stringent end-to-end latency requirement, which should not exceed 20 ms in order to avoid motion sickness and other discomforts. Bringing AR/VR to the next level to enable immersive interconnected AR/VR will require significant advances towards 5G ultra-reliable low-latency communication (URLLC) and a Tactile Internet of Things (IoT). In this article, we articulate the technical challenges to enable a future AR/VR end-to-end architecture, that combines 5G URLLC and Tactile IoT technology to support this next generation of interconnected AR/VR applications. Through the use of IoT sensors and actuators, AR/VR applications will be aware of the environmental and user context, supporting human-centric adaptations of the application logic, and lifelike interactions with the virtual environment. We present potential use cases and the required technological building blocks. For each of them, we delve into the current state of the art and challenges that need to be addressed before the dream of remote AR/VR interaction can become reality

Monte Carlo Simulations of Single-Molecule Fluorescence Detection Experiments

Several Monte Carlo simulations of single-molecule fluorescence systems are developed to help evaluate and improve ongoing experiments. In the first simulation, trapping of a single molecule in a nanochannel is studied. Molecules move along the nanochannel by diffusion and electrokinetic flow. Single-molecule fluorescence signals excited by two spatially offset laser beams are detected and the direction of the flow is adjusted to try to equalize the signals and center the molecule between the beams. An algorithm is evaluated for trapping individual molecules in succession by rapidly reloading the trap after a molecule photobleaches or escapes. This is shown to be effective for trapping fast-diffusing single-chromophore molecules in succession within a micron-sized confocal region while accommodating the limited electrokinetic speed and the finite latency of feedback imposed by experimental hardware. In the second simulation, trapping of a molecule in a two-dimensional fluidic device consisting of sub-micron-separated glass plates is studied. Two different illumination schemes for sensing the molecule\u27s position are compared: (i) a single continuous laser spot circularly scanned at 40 KHz or 240 KHz in the plane of the device; and (ii) four pulsed laser spots arranged in a square and temporally alternated at 304 MHz In either case, the times of detected photons are used by algorithms to control the electrokinetic flow in two dimensions to compensate diffusion and achieve single-molecule trapping. However each scheme is found to have limitations, as circular scanning produces a modulation in the fluorescence signal and in the autocorrelation function, whereas the four-pulse scheme becomes ineffective if the fluorescence lifetime of the molecule is greater than the time between laser pulses, The third simulation investigates appropriate conditions for detection of single molecules flowing through an array of fluidic channels for an application to high-throughput screening for pharmaceutical drug discovery. For parallelized single-molecule detection, illumination is provided by a continuous laser focused to a line intersecting all channels and fluorescence is imaged to a single row of pixels of an electron-multiplying CCD with sufficient gain for single-photon detection. The simulation separately models each channel to determine laser, flow, and camera operating conditions suitable for efficient detection

The Heavy Photon Search test detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment׳s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e+e− invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW04 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e+e− pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab

Měření Triple play služeb v hybridní síti

The master's thesis deals with a project regarding the implementation, design and the quality of IPTV, VoIP and Data services within the Triple Play services. In heterostructural networks made up of GEPON and xDSL technologies. Different lengths of the optical and metallic paths were used for the measurements. The first part of the thesis is theoretically analyzed the development and trend of optical and metallic networks. The second part deals with the measurement of typical optical and metallic parameters on the constructed experimental network, where its integrity was tested. Another part of the thesis is the evaluation of Triple play results, regarding the test where the network was variously tasked/burdened with data traffic and evaluated according to defined standards. The last part is concerned with the Optiwave Software simulation environment.Diplomová práce se zabývá návrhem, realizací a kvalitou služeb IPTV, VoIP a Data v rámci Triple play služeb v heterostrukturní sítí tvořené GEPON a xDSL technologiemi. Pro měření byli využity různé délky optické a metalické trasy. První části diplomové práce je teoreticky rozebrán vývoj a trend optických a metalických sítí. Druhá část se zaměřuje na měření typických optických a metalických parametrů na vybudované experimentální síti, kde byla následně testována její integrita. Dalším bodem práce je vyhodnocení výsledků Triple play, kde síť je různě zatěžována datovým provozem a následně vyhodnocována podle definovaných norem. Závěr práce je věnovaný simulačnímu prostředí Optiwave.440 - Katedra telekomunikační technikyvýborn

ATF2 Proposal

ATF2 Group Accelerator Physic

Optimizing Advanced Ligo\u27s Scientific Output with Fast, Accurate, Clean Calibration

Since 2015, the direct observation of gravitational waves has opened a new window to observe the universe and made strong-field tests of Einstein\u27s general theory of relativity possible for the first time. During the first two observing runs of the Advanced gravitational-wave detector network, the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Virgo detector have made 10 detections of binary black hole mergers and one detection of a binary neutron star merger with a coincident gamma-ray burst. This dissertation discusses methods used in low and high latency to produce Advanced LIGO\u27s calibrated strain data, highlighting improvements to accuracy, latency, and noise reduction that have been made since the beginning of the second observing run (O2). Systematic errors in the calibration during O2 varied by frequency, but were generally no greater that 5% in amplitude and 3 deg in phase from 20 Hz to 1 kHz. Due in part to this work, it is now possible to achieve calibration accuracy at the level of ~1% in amplitude and ~1 deg in phase, offering improvements to downstream astrophysical analyses. Since the beginning of O2, latency intrinsic to the calibration procedure has decreased from ~12 s to ~3 s. As latency in data distribution and the sending of automated alerts to astronomers is minimized, reduction in calibration latency will become important for follow-up of events like the binary neutron star merger GW170817. A method of removing spectral lines and broadband noise in the calibration procedure has been developed since O2, offering increases in total detectable volume during future observing runs. High-latency subtraction of lines and broadband noise had a large impact on astrophysical analyses during O2. A similar data product can now be made available in low latency for the first time

High-density microfibers as a deep brain bidirectional optical interface

Optical interrogation and manipulation of neural dynamics is a cornerstone of systems neuroscience. Genetic targeting enable delivering fluorescent indicators and opsins to specific neural subpopulations. Optic probes can fluorescently sense and convey calcium, voltage, and neurotransmitter dynamics. This optical toolkit enables recording and perturbing cellular-resolution activity in thousands of neurons across a field of view. Yet these techniques are limited by the light scattering properties of tissues. The cutting edge of microscopy, three-photon imaging, can record from intact tissues at depths up to 1 mm, but requires head-fixed experimental paradigms. To access deeper layers and non-cortical structures, researchers rely on optical implants, such as GRIN lenses or prisms, or the removal of superficial tissue. In this thesis, we introduce a novel implant for interfacing with deep brain regions constructed from bundles of hundreds or thousands of dissociated, small diameter (<8 µm) optical fibers. During insertion into the tissue, the fibers move independently, splaying through the target region. Each fiber achieves near total internal reflection, acting as a bidirectional optical interface with a small region of tissue near the fiber aperture. The small diameter and flexibility of the fibers minimize tissue response, preserving local connectivity and circuit dynamics. Histology and immunohistochemistry from implants into zebra finch basal ganglia (depth 2.9 mm) show the splaying of the fibers and the presence of NeuN-stained cells in close proximity to the fiber tips. By modeling the optical properties of the fibers and tissue, we simulate the interface properties of a bundle of fibers. Overlap in the sensitivity between nearby fibers allows application of blind source separation to extract individual neural traces. We describe a nonnegative independent component analysis algorithm especially suited to the interface. Finally, experimental data from implants in transgenic mice yield proof of principle recordings during both cortical spreading depolarization and forepaw stimulation. Collectively, the data presented here paint a compelling picture of splaying microfibers as a deep brain interface capable of sampling or perturbing neural activity at hundreds or thousands of points throughout a 3D volume of tissue while eliciting less response than existing optical implants