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

The task of characterizing optical wave propagation through the earth's atmosphere under low-visibility weather conditions is extremely difficult; it requires, in essence, solution of the general multiple-scattering problem This paper describes results from an integrated approach to propagation through the turbid atmosphere in which experiments are used to establish the magnitude of the propagation effects and to supply empirical relationships which permit simplifying approximations in the theory In particular, line-of-sight laser measurements of multipath spread, angular spread, beam spread, and incoherent source measurements of angular spread and power transmission versus range are reported From the behavior of these data two approximate propagation theories, viz, multiple forward scatter and strong multiple scatter, are developed

Atmospheric Optical Propagation: An Integrated Approach

Qubit entanglement is a valuable resource for quantum information processing, where increasing its dimensionality provides a pathway towards higher capacity and increased error resilience in quantum communications, cluster computation and quantum phase measurements. Time-frequency entanglement, a continuous variable subspace, enables the high-dimensional encoding of multiple qubits per particle, bounded only by the spectral correlation bandwidth and readout timing jitter. Extending from a dimensionality of two in discrete polarization variables, here we demonstrate a hyperentangled, mode-locked, biphoton frequency comb with a time-frequency Hilbert space dimensionality of at least 648. Hong-Ou-Mandel revivals of the biphoton qubits are observed with 61 time-bin recurrences, biphoton joint spectral correlations over 19 frequency-bins, and an overall interference visibility of the high-dimensional qubits up to 98.4%. We describe the Schmidt mode decomposition analysis of the high-dimensional entanglement, in both time- and frequency-bin subspaces, not only verifying the entanglement dimensionality but also examining the time-frequency scaling. We observe a Bell violation of the high-dimensional qubits up to 18.5 standard deviations, with recurrent correlation-fringe Clauser-Horne-Shimony-Holt S-parameter up to 2.771. Our biphoton frequency comb serves as a platform for dense quantum information processing and high-dimensional quantum key distribution.

/pdf/648-hilbert-space-dimensionality-in-a-biphoton-frequency-lb5a4fn5an.pdf

648 Hilbert space dimensionality in a biphoton frequency comb

The capacity C for transmitting classical information is investigated for Bosonic channels with isotropic Gaussian noise. For the pure‐loss channel—in which signal photons may be lost in propagation—the exact value of C is derived. The Holevo information of this channel is shown to be additive, and a “classical” encoding procedure employing coherent states is shown to achieve capacity. For active channel models—in which noise photons are injected from an external environment or the signal is amplified with unavoidable quantum noise—upper and lower bounds are obtained for the capacity. These bounds are asymptotically tight at low and high noise levels. Exact capacity results—given by the lower bounds—would follow from proving the conjecture that a coherent‐state input minimizes the output entropy from such channels.

https://www.rle.mit.edu/quantummuri/publications/Additions4_05/Maccone_8.pdf

Capacity of Bosonic Communications

Signal and idler beams from a type I phase-matched nondegenerate optical parametric oscillator are separated by a Mach-Zehnder interferometer. Broadband nonclassical intensity correlation is observed, in agreement with a theory that includes pump noise. The maximum observed correlation, which occurs at 1.1 MHz, yields a noise level 2.8 dB below the shot noise.

Nonclassical intensity correlation from a type I phase-matched optical parametric oscillator.

Previous analyses of conditional ${\ensuremath{\varphi}}_{nl}$-phase gates for photonic qubits that treat cross-phase modulation (XPM) in a causal, multimode, quantum field setting suggest that a large ($\ensuremath{\sim}$$\ensuremath{\pi}$ rad) nonlinear phase shift is always accompanied by fidelity-degrading noise [J. H. Shapiro, Phys. Rev. A 73, 062305 (2006); J. Gea-Banacloche, Phys. Rev. A 81, 043823 (2010)]. Using an atomic $\ensuremath{\vee}$ system to model an XPM medium, we present a conditional phase gate that, for sufficiently small nonzero ${\ensuremath{\varphi}}_{nl}$, has high fidelity. The gate is made cascadable by using a special measurement, i.e., principal-mode projection, to exploit the quantum Zeno effect and preclude the accumulation of fidelity-degrading departures from the principal-mode Hilbert space when both control and target photons illuminate the gate. The nonlinearity of the $\ensuremath{\vee}$ system we study is too weak for this particular implementation to be practical. Nevertheless, the idea of cascading through principal-mode projection is of potential use to overcome fidelity-degrading noise for a wide variety of nonlinear optical primitive gates.

/pdf/deterministic-and-cascadable-conditional-phase-gate-for-2qcaougb4v.pdf

Jeffrey H. Shapiro

Papers

Atmospheric Optical Propagation: An Integrated Approach

648 Hilbert space dimensionality in a biphoton frequency comb

Capacity of Bosonic Communications

Nonclassical intensity correlation from a type I phase-matched optical parametric oscillator.

Deterministic and cascadable conditional phase gate for photonic qubits