There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

From the Publisher: 
The accessible presentation of this book gives both a general view of the entire computer vision enterprise and also offers sufficient detail to be able to build useful applications. Users learn techniques that have proven to be useful by first-hand experience and a wide range of mathematical methods. A CD-ROM with every copy of the text contains source code for programming practice, color images, and illustrative movies. Comprehensive and up-to-date, this book includes essential topics that either reflect practical significance or are of theoretical importance. Topics are discussed in substantial and increasing depth. Application surveys describe numerous important application areas such as image based rendering and digital libraries. Many important algorithms broken down and illustrated in pseudo code. Appropriate for use by engineers as a comprehensive reference to the computer vision enterprise.

Computer vision : a modern approach = 计算机视觉 : 一种现代的方法

Researchers demonstrate the ability to multiplex and transfer data between twisted beams of light with different amounts of orbital angular momentum — a development that provides new opportunities for increasing the data capacity of free-space optical communications links.

/pdf/terabit-free-space-data-transmission-employing-orbital-47zsgn5cdx.pdf

Terabit free-space data transmission employing orbital angular momentum multiplexing

We propose a hetero-homodyne receiver for quantum illumination (QI) target detection. Unlike prior QI receivers, it uses a cascaded positive operator-valued measurement (POVM) that does not require a quantum interaction between QI's returned radiation and its stored idler. When used without sequential detection its performance matches the 3 dB quantum advantage over optimum classical illumination (CI) that Guha and Erkmen's [Phys. Rev. A 80, 052310 (2009)] phase-conjugate and parametric amplifier receivers enjoy. When used in a sequential detection QI protocol, the hetero-homodyne receiver offers a 9 dB quantum advantage over a conventional CI radar, and a 3 dB advantage over a CI radar with sequential detection. Our work is a significant step forward toward a practical quantum radar for the microwave region, and, more generally, emphasizes the potential offered by cascaded POVMs for quantum radar.

Quantum Illumination with a Hetero-Homodyne Receiver and Sequential Detection

Recently, Chen et al (2011 New J. Phys. 13 083018) presented experimental results, accompanied by quantum-mechanical analysis, showing that the quantum interference behavior of Bell states could be simulated in a modified Mach?Zehnder interferometer whose inputs are pseudothermal light beams obtained by passing laser light through a rotating ground-glass diffuser. Their experiments and their theory presumed low-flux operation in which the simulated quantum interference is observed via photon-coincidence counting. This work is a comment on the paper by Chen et al (2011). We first show that the Chen et al photon-coincidence counting experiments can be fully explained with semiclassical photodetection theory, in which light is taken to be a classical electromagnetic wave, and the discreteness of the electron charge leads to shot noise as the fundamental photodetection noise. We then use semiclassical photodetection theory to show that the same simulated quantum interference pattern can be observed in high-flux operation when photocurrent cross-correlation is used instead of photon-coincidence counting.

https://dspace.mit.edu/openaccess-disseminate/1721.1/72486

Comment on ‘Simulation of Bell states with incoherent thermal light’

Quantum illumination transmits part of an entangled state, retaining the rest for subsequent joint measurement in detection, imaging, or communication It outperforms classical-state systems of the same average transmitted energy over entanglement-breaking channels

Quantum Illumination for Improved Detection, Imaging, and Communication

An economical version of asymmetric phase-covariant cloning is shown to provide an optimal individual attack on the BB84 protocol with error correction that can be physically simulated using deterministic single-photon two-qubit quantum logic.

Optimal Individual Attacks against BB84

We establish a framework for evaluating CPHASE gates that use single-photon Kerr nonlinearities in which one pulse overtakes another. We show that causality-induced phase noise precludes the possibility of high-fidelity π-radian conditional phase shifts.

Jeffrey H. Shapiro

Papers

Quantum Illumination with a Hetero-Homodyne Receiver and Sequential Detection

Comment on ‘Simulation of Bell states with incoherent thermal light’

Quantum Illumination for Improved Detection, Imaging, and Communication

Optimal Individual Attacks against BB84

Phase-Noise Limitations on Nonlinear-Optical Quantum Computing