Packed Ultra-wideband Mapping Array (PUMA): A Radio Telescope for Cosmology and Transients

PUMA is a proposal for an ultra-wideband, low-resolution and transit interferometric radio telescope operating at $200-1100\,\mathrm{MHz}$. Its design is driven by six science goals which span three science themes: the physics of dark energy (measuring the expansion history and growth of the universe up to $z=6$), the physics of inflation (constraining primordial non-Gaussianity and primordial features) and the transient radio sky (detecting one million fast radio bursts and following up SKA-discovered pulsars). We propose two array configurations composed of hexagonally close-packed 6m dish arrangements with 50% fill factor. The initial 5,000 element 'petite array' is scientifically compelling, and can act as a demonstrator and a stepping stone to the full 32,000 element 'full array'. Viewed as a 21cm intensity mapping telescope, the program has the noise equivalent of a traditional spectroscopic galaxy survey comprised of 0.6 and 2.5 billion galaxies at a comoving wavenumber of $k=0.5\,h\mathrm{Mpc}^{-1}$ spanning the redshift range $z = 0.3 - 6$ for the petite and full configurations, respectively. At redshifts beyond $z=2$, the 21cm technique is a uniquely powerful way of mapping the universe, while the low-redshift range will allow for numerous cross-correlations with existing and upcoming surveys. This program is enabled by the development of ultra-wideband radio feeds, cost-effective dish construction methods, commodity radio-frequency electronics driven by the telecommunication industry and the emergence of sufficient computing power to facilitate real-time signal processing that exploits the full potential of massive radio arrays. The project has an estimated construction cost of 55 and 330 million FY19 USD for the petite and full array configurations. Including R&D, design, operations and science analysis, the cost rises to 125 and 600 million FY19 USD, respectively.Comment: 10 pages + references, 3 figures, 3 tables; project white paper submitted to the Astro2020 decadal survey; further details in updated arXiv:1810.0957

Equivalent Force Extraction Methodology For Electrical Component Induced PCB Vibration

On-board electrical components can cause printed circuit board (PCB) vibration, thus generating audio noise if the electrical noise is in the audible frequency range. The electrical component-induced vibration can be equated to an external force applied to the PCB. This article presents a novel methodology to extract the equivalent force of electrical components on a PCB to study board vibration and potential acoustic noise problems. The method is based on a combination of measurement and simulation, wherein PCB vibration is used as the medium in the extraction process. The methodology is validated by the correlation of PCB vibration pattern, frequency, and amplitude with a known electromagnetic force applied to the PCB

Aircraft Electrical Wiring Monitoring System

International audienceThe cumulated lengths of electrical cables continuously increases in aircrafts and trucks: now up to 10kilometers in a modern truck, 40 km in a helicopter or in a fighter aircraft and 500 km in a modern civiltransport aircraft such as A380. Electrical wiring is a critical part in the nominal operation of a system. Theimportance of the wired network has thus grown to the same level as the systems it is connected to [1].Regarding the increasing complexity of the electric system (increase in the number of electric loads, in thesupply voltages), the regulation authorities (FAA, Federal Aviation Administration and EASA, European AviationSafety Agency ) now require to consider aircrafts’ electrical wiring as a system on its own, named EWIS(Electrical Wiring Interconnection System)

Highlights of the SLD Physics Program at the SLAC Linear Collider

Starting in 1989, and continuing through the 1990s, high-energy physics witnessed a flowering of precision measurements in general and tests of the standard model in particular, led by e+e- collider experiments operating at the Z0 resonance. Key contributions to this work came from the SLD collaboration at the SLAC Linear Collider. By exploiting the unique capabilities of this pioneering accelerator and the SLD detector, including a polarized electron beam, exceptionally small beam dimensions, and a CCD pixel vertex detector, SLD produced a broad array of electroweak, heavy-flavor, and QCD measurements. Many of these results are one of a kind or represent the world's standard in precision. This article reviews the highlights of the SLD physics program, with an eye toward associated advances in experimental technique, and the contribution of these measurements to our dramatically improved present understanding of the standard model and its possible extensions.Comment: To appear in 2001 Annual Review of Nuclear and Particle Science; 78 pages, 31 figures; A version with higher resolution figures can be seen at http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8985.html; Second version incorporates minor changes to the tex

Superconducting Quantum Metamaterials

Superconducting quantum metamaterials extend the idea of their classical counterpart to a regime where their constituent meta-atoms are quantum objects, which can hold their quantum coherence for longer than the propagation time of light through the medium. In this work, we have realized a quantum metamaterial consisting of eight individually controllable superconducting transmon qubits, which are coupled to the mode continuum of a one-dimensional coplanar waveguide. This system can be described within the framework of waveguide-quantum electrodynamics, which predicates that the mutual interaction of the qubits with the waveguide gives rise to long-range interactions of the qubits. In spectroscopic measurements we observe the formation of super- and subradiant collective metamaterial excitations, as well as the emergence of a polaritonic band gap and study their dependence on the number of participating resonant qubits. We utilize the collective Autler-Townes splitting of the metamaterial to demonstrate control over its band gap. Furthermore, we exploit the control over the band structure for a first realization of slowly propagating light in the metamaterial. Our findings show that superconducting quantum metamaterials are a suitable platform to study fundamental excitations in solids and pave way to applications in quantum information processing like quantum memories

Tip-enhanced near-field optical microscopy of single-walled carbon nanotube/polymer conjugates and improvements of the image contrast

Semiconducting single-walled carbon nanotubes (s-SWCNTs) are regarded as a promising candidate for a wide range of applications. Particularly, tailored blends of single-walled carbon nanotubes with polymers are ideally suited for organic solar cells (OSC) due to their inherent stability, high carrier mobility and the tunability of optical band gaps. In the past, the mixing of semiconducting and metallic SWCNTs and their aggregation into bundles strongly hindered their practical applications. More recently, many techniques have been developed to separate SWCNTs into chirality-pure single carbon nanotube samples. Nowadays, the most common approach is non-covalent polymer or surfactant wrapping. However, the characterization of these SWCNT samples is usually limited to a macroscopic level and few studies have looked into the interaction between SWCNTs and the wrapping agent on the single nanotube level. A comparison of the effects of different wrapping agents could provide useful guideline for device fabrication. Tip-enhanced near-field optical microscopy (TENOM) achieves 10 - 20 nm spatial resolution and substantial signal enhancement by employing an optical antenna such as a gold tip to localize and enhance light-matter interactions. In the first part of the thesis, we utilized TENOM to study the photoluminescence (PL) of single SWCNTs in different sample materials and investigated their optical heterogeneity. We introduced a statistical parameter to evaluate the intensity fluctuation of the near-field PL, which yields information on the occurrence of exciton trapping sites and quenching defects. We compared the results from different wrapping agents and post-synthesis treatment, and found that CVD synthesized SWCNTs, without further treatment together with PFO-BPy as wrapping agent exhibits the highest level of optical homogeneity. For TENOM and other types of scanning near-field optical microscopy (SNOM) as well, the presence of a far-field background from laser illumination of the sample lowers the signal to background ratio and decreases detection sensitivity. The second part of the thesis aims at suppressing the far-field background. We implemented a new tuning fork configuration in which the tip oscillates normal to the sample surface in a tuning-fork based TENOM setup, and drove an oscillation amplitude larger than the near-field decay length. A switch with a tunable threshold was used to extract the far-field part, which was subsequently subtracted from the total signal. Theoretical calculations were first performed to find the optimal tip modulation depth and switch threshold. The new configuration was finally applied to SWCNT PL imaging and was proven to significantly enhance the signal to background ratio

Studying Light-Harvesting Models with Superconducting Circuits

The process of photosynthesis, the main source of energy in the animate world, converts sunlight into chemical energy. The surprisingly high efficiency of this process is believed to be enabled by an intricate interplay between the quantum nature of molecular structures in photosynthetic complexes and their interaction with the environment. Investigating these effects in biological samples is challenging due to their complex and disordered structure. Here we experimentally demonstrate a new approach for studying photosynthetic models based on superconducting quantum circuits. In particular, we demonstrate the unprecedented versatility and control of our method in an engineered three-site model of a pigment protein complex with realistic parameters scaled down in energy by a factor of $10^5$. With this system we show that the excitation transport between quantum coherent sites disordered in energy can be enabled through the interaction with environmental noise. We also show that the efficiency of the process is maximized for structured noise resembling intramolecular phononic environments found in photosynthetic complexes.Comment: 8+12 pages, 4+12 figure

Noncontact Vital Signs Detection

Human health condition can be accessed by measurement of vital signs, i.e., respiratory rate (RR), heart rate (HR), blood oxygen level, temperature and blood pressure. Due to drawbacks of contact sensors in measurement, non-contact sensors such as imaging photoplethysmogram (IPPG) and Doppler radar system have been proposed for cardiorespiratory rates detection by researchers.The UWB pulse Doppler radars provide high resolution range-time-frequency information. It is bestowed with advantages of low transmitted power, through-wall capabilities, and high resolution in localization. However, the poor signal to noise ratio (SNR) makes it challenging for UWB radar systems to accurately detect the heartbeat of a subject. To solve the problem, phased-methods have been proposed to extract the phase variations in the reflected pulses modulated by human tiny thorax motions. Advance signal processing method, i.e., state space method, can not only be used to enhance SNR of human vital signs detection, but also enable the micro-Doppler trajectories extraction of walking subject from UWB radar data.Stepped Frequency Continuous Wave (SFCW) radar is an alternative technique useful to remotely monitor human subject activities. Compared with UWB pulse radar, it relieves the stress on requirement of high sampling rate analog-to-digital converter (ADC) and possesses higher signal-to-noise-ratio (SNR) in vital signs detection. However, conventional SFCW radar suffers from long data acquisition time to step over many frequencies. To solve this problem, multi-channel SFCW radar has been proposed to step through different frequency bandwidths simultaneously. Compressed sensing (CS) can further reduce the data acquisition time by randomly stepping through 20% of the original frequency steps.In this work, SFCW system is implemented with low cost, off-the-shelf surface mount components to make the radar sensors portable. Experimental results collected from both pulse and SFCW radar systems have been validated with commercial contact sensors and satisfactory results are shown