59 research outputs found
OpenFermion: The Electronic Structure Package for Quantum Computers
Quantum simulation of chemistry and materials is predicted to be an important
application for both near-term and fault-tolerant quantum devices. However, at
present, developing and studying algorithms for these problems can be difficult
due to the prohibitive amount of domain knowledge required in both the area of
chemistry and quantum algorithms. To help bridge this gap and open the field to
more researchers, we have developed the OpenFermion software package
(www.openfermion.org). OpenFermion is an open-source software library written
largely in Python under an Apache 2.0 license, aimed at enabling the simulation
of fermionic models and quantum chemistry problems on quantum hardware.
Beginning with an interface to common electronic structure packages, it
simplifies the translation between a molecular specification and a quantum
circuit for solving or studying the electronic structure problem on a quantum
computer, minimizing the amount of domain expertise required to enter the
field. The package is designed to be extensible and robust, maintaining high
software standards in documentation and testing. This release paper outlines
the key motivations behind design choices in OpenFermion and discusses some
basic OpenFermion functionality which we believe will aid the community in the
development of better quantum algorithms and tools for this exciting area of
research.Comment: 22 page
Erratum to: Search for diboson resonances in hadronic final states in 139 fbâ1 of pp collisions at sâ = 13 TeV with the ATLAS detector
A mistake was identified for the paper [1] in the treatment of the radion [2] cross-sections, which resulted in multiple changes.(undefined)info:eu-repo/semantics/publishedVersio
Quantum circuits with many photons on a programmable nanophotonic chip
Growing interest in quantum computing for practical applications has led to a
surge in the availability of programmable machines for executing quantum
algorithms. Present day photonic quantum computers have been limited either to
non-deterministic operation, low photon numbers and rates, or fixed random gate
sequences. Here we introduce a full-stack hardware-software system for
executing many-photon quantum circuits using integrated nanophotonics: a
programmable chip, operating at room temperature and interfaced with a fully
automated control system. It enables remote users to execute quantum algorithms
requiring up to eight modes of strongly squeezed vacuum initialized as two-mode
squeezed states in single temporal modes, a fully general and programmable
four-mode interferometer, and genuine photon number-resolving readout on all
outputs. Multi-photon detection events with photon numbers and rates exceeding
any previous quantum optical demonstration on a programmable device are made
possible by strong squeezing and high sampling rates. We verify the
non-classicality of the device output, and use the platform to carry out
proof-of-principle demonstrations of three quantum algorithms: Gaussian boson
sampling, molecular vibronic spectra, and graph similarity
Sublithospheric diamond ages and the supercontinent cycle.
Subduction related to the ancient supercontinent cycle is poorly constrained by mantle samples. Sublithospheric diamond crystallization records the release of melts from subducting oceanic lithosphere at 300-700âkm depths1,2 and is especially suited to tracking the timing and effects of deep mantle processes on supercontinents. Here we show that four isotope systems (Rb-Sr, Sm-Nd, U-Pb and Re-Os) applied to Fe-sulfide and CaSiO3 inclusions within 13 sublithospheric diamonds from JuĂna (Brazil) and Kankan (Guinea) give broadly overlapping crystallization ages from around 450 to 650 million years ago. The intracratonic location of the diamond deposits on Gondwana and the ages, initial isotopic ratios, and trace element content of the inclusions indicate formation from a peri-Gondwanan subduction system. Preservation of these Neoproterozoic-Palaeozoic sublithospheric diamonds beneath Gondwana until its Cretaceous breakup, coupled with majorite geobarometry3,4, suggests that they accreted to and were retained in the lithospheric keel for more than 300âMyr during supercontinent migration. We propose that this process of lithosphere growth-with diamonds attached to the supercontinent keel by the diapiric uprise of depleted buoyant material and pieces of slab crust-could have enhanced supercontinent stability
Trocas gasosas e fluorescĂȘncia da clorofila em plantas de berinjela sob lĂąminas de irrigação
A guide to the crystallographic analysis of icosahedral viruses
Determining the structure of an icosahedral virus crystal by X-ray diffraction follows very much the same course as conventional protein crystallography. The major differences arise from the relatively large sizes of the particles, which significantly affect the data collection process, data processing and management, and later, the refinement of a model. Most of the other differences are due to the high 5 3 2 point group symmetry of icosahedral viruses. This alters dramatically the means by which initial phases are obtained by molecular substitution, extended to higher resolution by electron density averaging and density modification, and the refinement of the structure in the light of high non-crystallographic symmetry. In this review, we attempt to lead the investigator through the various steps involved in solving the structure of a virus crystal. These steps include the purification of viruses, their crystallization, the recording of X-ray diffraction data, and its reduction to structure amplitudes. It further addresses the problems attending phase determination and ultimately the refinement of a model. Finally, we describe the unique properties of virus crystals and the factors that influence their physical and diffraction properties
Performance and interpretation: Beethoven\u27s Opus 110
Within the context of professional music making, an increasing number of pianists use both modern and historical pianos as a matter of course. Yet, not infrequently, it seems that there is little awareness of how the inherent acoustic characteristics of each instrument may be used to inform interpretation, and the instrument-specific pianistic techniques that are needed if interpretation is to be optimised. This study explores issues of interpretation and performance as applied to Beethovenâs Piano Sonata in Ab major, op. 110. Three different performative interpretations of the sonata are constructed, each relating to a specific grand pianoââmade by, respectively, Conrad Graf (1819), John Broadwood & Sons (1824), and Paolo Fazioli (2013). The interpretations are created within the context of âhands onâ experience with each of the pianos, and are formed through both reflective practice andâin the case of the Graf and Broadwood instrumentsâthe investigation of historical sources that include pertinent comments regarding performance practice. For the interpretation expressed using the Fazioli piano, the study draws upon Daniel Leech-Wilkinsonâs notion that fidelity to the written score is not a governing protocol, and that a performative interpretation may depart not only from the score, but also from commonly held interpretative and aesthetic pre-conceptions and expectations. Through its reflective approach to interpretation and performance, this study aims to contribute to the unveiling of meaning in Beethovenâs op. 110, and to be a catalyst for deeper interpretative insights
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