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Arxiv.org
by J. G. H. Franssen; T. L. I. Frankort; E. J. D. Vredenbregt; O. J. Luiten
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We present measurements of the pulse length of ultracold electron bunches generated by near-threshold two-photon photoionization of a laser-cooled gas. The pulse length has been measured using a resonant $3$ GHz deflecting cavity in TM$_{110}$ mode. We have measured the pulse length in three ionization regimes. The first is direct two-photon photoionization using only a $480$ nm femtosecond laser pulse, which results in short ($\sim 15$ ps) but hot ($\sim 10^{4}$ K) electron bunches. The second...
Topics: Atomic Physics, Accelerator Physics, Physics, Plasma Physics
Source: http://arxiv.org/abs/1701.07686
Arxiv.org
by Alexandre Gondran; Michel Gondran
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Playing the game of heads or tails in zero gravity demonstrates that there exists a contextual "measurement" in classical mechanics. When the coin is flipped, its orientation is a continuous variable. However, the "measurement" that occurs when the coin is caught by clapping two hands together gives a discrete value (heads or tails) that depends on the context (orientation of the hands). It is then shown that there is a strong analogy with the spin measurement of the...
Topics: Physics, Physics Education, Quantum Physics, Classical Physics
Source: http://arxiv.org/abs/1703.07550
Arxiv.org
by Manaka Okuyama; Kazutaka Takahashi
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We formulate the theory of shortcuts to adiabaticity in classical mechanics. For a reference Hamiltonian, the counterdiabatic term is constructed from the dispersionless Korteweg-de Vries (KdV) hierarchy. Then the adiabatic theorem holds exactly for an arbitrary choice of time-dependent parameters. We use the Hamilton-Jacobi theory to define the generalized action. The action is independent of the history of the parameters and is directly related to the adiabatic invariant. The dispersionless...
Topics: Physics, Quantum Physics, Classical Physics
Source: http://arxiv.org/abs/1701.07927
Arxiv.org
by Eugene Surdutovich; Alexey Verkhovtsev; Andrey V. Solov'yov
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An instability of a liquid droplet traversed by an energetic ion is explored. This instability is brought about by the predicted shock wave induced by the ion. An observation of multifragmentation of small droplets traversed by ions with high linear energy transfer is suggested to demonstrate the existence of shock waves. A number of effects are analysed in effort to find the conditions for such an experiment to be signifying. The presence of shock waves crucially affects the scenario of...
Topics: Biological Physics, Physics, Medical Physics
Source: http://arxiv.org/abs/1702.06801
Arxiv.org
by T. A. Haase; D. H. White; D. J. Brown; I. Herrera; M. D. Hoogerland
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We report on the implementation of a novel optical setup for generating high-resolution customizable potentials to address ultracold bosonic atoms in 2D. Two key features are developed for this purpose. The customizable potential is produced with a direct image of a spatial light modulator, conducted with an in-vacuum imaging system of high numerical aperture. Custom potentials are drawn over an area of 600 $\times$ 400 {\mu}m with a spot-size of 1 {\mu}m. The second development is a...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.01860
Arxiv.org
by Daiju Nakayama; Kin-ya Oda
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We present how to implement the special relativity in computer games. The resultant relativistic world exactly shows the time dilation and Lorentz contraction, not only for the player but also for all the non-player characters, who obey the correct relativistic equation of motion according to their own accelerations. The causality is explicitly maintained in our formulation by use of the covariant velocities, proper times, worldlines, and light cones. Far-away relativistic scenes can be...
Topics: Physics, Computational Physics, Classical Physics
Source: http://arxiv.org/abs/1703.07063
Arxiv.org
by Gianluca Geloni; Vitali Kocharyan; Evgeni Saldin
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It is generally accepted that the dynamics of relativistic particles in the lab frame can be described by taking into account the relativistic dependence of the particles momenta on the velocity, with no reference to Lorentz transformations. The electrodynamics problem can then be treated within a "single inertial frame" description. To evaluate radiation fields from moving charged particles we need their velocities and positions as a function of the lab frame time t. The relativistic...
Topics: Accelerator Physics, Physics, Plasma Physics, Classical Physics
Source: http://arxiv.org/abs/1704.01843
Arxiv.org
by C. A. Downing
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We present analytical solutions to a quantum-mechanical three-body problem in three dimensions, which describes a helium-like two-electron atom. Similarly to Hooke's atom, the Coulombic electron-nucleus interaction potentials are replaced by harmonic potentials. The electron-electron interaction potential is taken to be both screened (decaying faster than the inverse of the interparticle separation) and regularized (in the limit of zero separation). We reveal the exactly solvable few-electron...
Topics: Physics, Quantum Physics, Mathematical Physics, Chemical Physics, Mathematics
Source: http://arxiv.org/abs/1702.03960
Arxiv.org
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We investigate laser-induced quantum interference phenomena in superradiance processes and in an ensemble of initially excited $\Lambda-$type closely packed three-level emitters. The lower doublet levels are pumped with a coherent laser field. Due to constructive quantum interference effects, the superradiance occurs on a much weaker atomic transition which is not the case in the absence of the coherent driving. This result may be of visible relevance for enhancing ultraweak transitions in...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1704.05723
Arxiv.org
by Olov Pettersson; Tim Byrnes
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We analyze a similar scheme for producing light-mediated entanglement between atomic ensembles, as first realized by Julsgaard, Kozhekin and Polzik [Nature {\bf 413}, 400 (2001)]. In the standard approach to modeling the scheme, a Holstein-Primakoff approximation is made, where the atomic ensembles are treated as bosonic modes, and is only valid for short interaction times. In this paper, we solve the time evolution without this approximation, which extends the region of validity of the...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.07974
Arxiv.org
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We have calculated the ground state spectroscopic constants and the molecular properties, of a molecular ion BeLi + , such as dipole moment, quadrupole moment and dipole polarizability at different levels of correlation: many-body perturbation theory (MP2), coupled cluster method with single and double excitations (CCSD) and CCSD with perturbative triples (CCSD(T)). The correlation consistent polarized valence cc-pVXZ (X=D, T, Q) basis sets and also their augmented counterparts are used...
Topics: Atomic Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1702.07218
Arxiv.org
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The Wannier localization problem in quantum physics is mathematically analogous to finding a localized representation of a subspace corresponding to a nonlinear eigenvalue problem. While Wannier localization is well understood for insulating materials with isolated eigenvalues, less is known for metallic systems with entangled eigenvalues. Currently, the most widely used method for treating systems with entangled eigenvalues is to first obtain a reduced subspace (often referred to as...
Topics: Physics, Computational Physics, Chemical Physics
Source: http://arxiv.org/abs/1703.06958
Arxiv.org
by Jie Yao; Cameron L. Williams; Fazle Hussain; Donald J. Kouri
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The solution of a nonlinear diffusion equation is numerically investigated using the generalized Fourier transform method. This equation includes fractal dimensions and power-law dependence on the radial variable and on the diffusion function. The generalized Fourier transform approach is the extension of the Fourier transform method used for normal diffusion equation. The feasibility of the approach is validated by comparing the numerical result with the exact solution for point-source. The...
Topics: Physics, Computational Physics, Classical Physics
Source: http://arxiv.org/abs/1701.03488
Arxiv.org
by Giorgio Colangelo; Ferran Martin Ciurana; Lorena C. Bianchet; Robert J. Sewell; Morgan W. Mitchell
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We show how simultaneous, back-action evading tracking of non-commuting observables can be achieved in a widely-used sensing technology, atomic interferometry. Using high-dynamic-range dynamically-decoupled quantum non-demolition (QND) measurements on a precessing atomic spin ensemble, we track the collective spin angle and amplitude with negligible effects from back action, giving steady-state tracking sensitivity 2.9 dB beyond the standard quantum limit and 7.0 dB beyond Poisson statistics.
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.08888
Arxiv.org
by Matt G Hall; Gemma Nedjati-Gilani; Daniel C Alexander
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To synthesize diffusion MR measurements from Monte-Carlo simulation using tissue models with sizes comparable to those of scan voxels. Larger regions enable restricting structures to be modeled in greater detail and improve accuracy and precision in synthesized diffusion-weighted measurements. We employ a localized intersection checking algorithm during substrate construction and dynamical simulation. Although common during dynamics simulation, a dynamically constructed intersection map is also...
Topics: Physics, Computational Physics, Medical Physics
Source: http://arxiv.org/abs/1701.03634
Arxiv.org
by Ari Le; William Daughton; Li-Jen Chen; Jan Egedal
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Electron heating and mixing during asymmetric reconnection are studied with a 3D kinetic simulation that matches plasma parameters from Magnetospheric Multiscale (MMS) spacecraft observations of a magnetopause diffusion region. The mixing and heating are strongly enhanced across the magnetospheric separatrix compared to a 2D simulation. The transport of particles across the separatrix in 3D is attributed to lower-hybrid drift turbulence excited at the steep density gradient near the...
Topics: Plasma Physics, Physics, Space Physics
Source: http://arxiv.org/abs/1703.10246
Arxiv.org
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We present a generalization of the Debye-H\"uckel free-energy-density functional of simple fluids to the case of two-component systems with arbitrary interaction potentials. It allows one to obtain the two-component Debye-H\"uckel integral equations through its minimization with respect to the pair correlation functions, leads to the correct form of the internal energy density, and fulfills the virial theorem. It is based on our previous idea, proposed for the one-component...
Topics: Plasma Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.06502
Arxiv.org
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We have developed the first laser damage simulation algorithm capable of determining crater and surface modification morphology from microscopic physics. Rapid progress in the field of high intensity ultrafast lasers has enabled its utility in a myriad of applications. Simulation plays an important role in this research by allowing for closer analysis of the physical mechanisms involved, but current techniques struggle to meet both the spatial scope or resolution requirements for modeling such...
Topics: Applied Physics, Physics, Computational Physics
Source: http://arxiv.org/abs/1704.07482
Arxiv.org
by Gleb Maslennikov; Shiqian Ding; Roland Hablutzel; Jaren Gan; Alexandre Roulet; Stefan Nimmrichter; Jibo Dai; Valerio Scarani; Dzmitry Matsukevich
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Thermodynamics is one of the oldest and well-established branches of physics that sets boundaries to what can possibly be achieved in macroscopic systems. While it started as a purely classical theory, it was realized in the early days of quantum mechanics that large quantum devices, such as masers or lasers, can be treated with the thermodynamic formalism. Remarkable progress has been made recently in the miniaturization of heat engines all the way to the single Brownian particle as well as to...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.08672
Arxiv.org
by Pablo de Vera; Eugene Surdutovich; Nigel J. Mason; Andrey V. Solov'yov
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Energetic ions lose their energy in tissue mainly by ionising its molecules. This produces secondary electrons which transport this energy radially away from the ion path. The ranges of most of these electrons do not exceed a few nanometres, therefore large energy densities (radial doses) are produced within a narrow region around the ion trajectory. Large energy density gradients correspond to large pressure gradients and this brings about shock waves propagating away from the ion path....
Topics: Medical Physics, Physics, Biological Physics
Source: http://arxiv.org/abs/1703.04602
Arxiv.org
by Thomas Lauprêtre; Rasmus B. Linnet; Ian D. Leroux; Aurélien Dantan; Michael Drewsen
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We demonstrate light-induced localization of Coulomb-interacting particles in multi-dimensional structures. Subwavelength localization of ions within small multi-dimensional Coulomb crystals by an intracavity optical standing wave field is evidenced by measuring the difference in scattering inside symmetrically red- and blue-detuned optical lattices and is observed even for ions undergoing substantial radial micromotion. These results are promising steps towards the structural control of ion...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.05089
Quantitative nuclear magnetic resonance imaging (MRI) shifts more and more into the focus of clinical research. Especially determination of relaxation times without/and with contrast agents becomes the foundation of tissue characterization, e.g. in cardiac MRI for myocardial fibrosis. Techniques which assess longitudinal relaxation times rely on repetitive application of readout modules, which are interrupted by free relaxation periods, e.g. the Modified Look-Locker Inversion Recovery = MOLLI...
Topics: Biological Physics, Physics, Medical Physics
Source: http://arxiv.org/abs/1704.06898
Arxiv.org
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We evaluate the practical performance of the zero-multiple summation method (ZMM), a method for approximately calculating electrostatic interactions in molecular dynamics simulations. The performance of the ZMM is compared with that of the smooth particle mesh Ewald method (SPME). Even though the ZMM uses a larger cutoff distance than the SPME does, the performance of the ZMM is found to be comparable to or better than that of the SPME. In particular, the ZMM with quadrupole or octupole...
Topics: Physics, Computational Physics, Biological Physics
Source: http://arxiv.org/abs/1704.07071
Arxiv.org
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The way Quantum Mechanics (QM) is introduced to people used to Classical Mechanics (CM) is by a complete change of the general methodology despite QM historically stemming from CM as a means to explain experimental results. Therefore, it is desirable to build a bridge from CM to QM. This paper presents a generalization of CM to QM. It starts from the generalization of a point-like object and naturally arrives at the quantum state vector of quantum systems in the complex valued Hilbert space,...
Topics: Physics, Quantum Physics, General Physics
Source: http://arxiv.org/abs/1701.04698
Arxiv.org
by Daniel Cellucci; Benjamin Jenett; Kenneth C. Cheung
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It is widely assumed that human exploration beyond Earth's orbit will require vehicles capable of providing long-duration habitats that simulate an Earthlike environment: consistent artificial gravity, breathable atmosphere, and sufficient living space- while requiring the minimum possible launch mass. This paper examines how the qualities of digital cellular solids - high-performance, repairability, reconfigurability, tunable mechanical response - allow the accomplishment of long-duration...
Topics: Physics, Space Physics, Popular Physics
Source: http://arxiv.org/abs/1703.00044
Arxiv.org
by E. G. Drukarev; A. I. Mikhailov
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We show that the theoretical predictions on high energy behavior of the photoionization cross section of fullerenes depends crucially on the form of the function $V(r)$ which approximates the fullerene field. The shape of the high energy cross section is obtained without solving of the wave equation. The cross section energy dependence is determined by the analytical properties of the function $V(r)$.
Topics: Atomic Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1703.07712
Arxiv.org
by Samuel M. Blau; Doran I. G. Bennett; Christoph Kreisbeck; Gregory D. Scholes; Alán Aspuru-Guzik
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Mechanisms controlling excitation energy transport (EET) in light-harvesting complexes remain controversial. Following the observation of long-lived beats in two-dimensional electronic spectroscopy of PC645, vibronic coherence, the delocalization of excited states between pigments supported by a resonant vibration, has been proposed to enable direct down-conversion from the highest-energy states to the lowest-energy pigments. Here, we instead show that for phycobiliprotein PC645 an incoherent...
Topics: Physics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.05449
Arxiv.org
by Eugene Surdutovich; Andrey V. Solov'yov
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The problem of variable cell survival probability along the spread-out Bragg peak is one of the long standing problems in planning and optimisation of ion-beam therapy. This problem is considered using the multiscale approach to the physics of ion-beam therapy. The physical reasons for this problem are analysed and understood on a quantitative level. A recipe of solution to this problem is suggested using this approach. This recipe can be used in the design of a novel treatment planning and...
Topics: Biological Physics, Physics, Medical Physics
Source: http://arxiv.org/abs/1703.00596
Arxiv.org
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Coherent control of chaotic molecular systems, using laser-assisted alignment of sulphur dioxide (SO$_2$) molecules in the presence of a static electric field as an example, is considered. Conditions for which the classical version of this system is chaotic are established, and the quantum and classical analogs are shown to be in very good correspondence. It is found that the chaos present in the classical system does not impede the alignment, neither in the classical nor the quantum system....
Topics: Physics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1701.04448
Arxiv.org
by Arash Tirandaz; Farhad Taher Ghahramani; Afshin Shafiee
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We examine the olfactory discrimination of left- and right-handed enantiomers of chiral odorants based on the odorant-mediated electron transport from a donor to an acceptor of the olfactory receptors embodied in a biological environment. The chiral odorant is effectively described by an asymmetric double-well potential whose minima are associated to the left- and right-handed enantiomers. The introduced asymmetry is considered as an overall measure of chiral interactions. The biological...
Topics: Physics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.08129
Arxiv.org
by J. J. Bowen; V. M. Dwyer; I. W. Phillips; M. J. Everitt
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Due to the exponential growth of the state space of coupled quantum systems it is not possible, in general, to numerically store the state of a very large number of quantum systems within a classical computer. We demonstrate a method for modelling the dynamical behaviour of measurable quantities for very large numbers of interacting quantum systems. Our approach makes use of a symbolic non-commutative algebra engine that we have recently developed in conjunction with the well-known Ehrenfest...
Topics: Physics, Quantum Physics, Computational Physics
Source: http://arxiv.org/abs/1702.01723
Arxiv.org
by Alexandra Koulouri; Ville Rimpiläinen; Mike Brookes; Jari P Kaipio
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In electroencephalography (EEG) source imaging, the inverse source estimates are depth biased in such a way that their maxima are often close to the sensors. This depth bias can be quantified by inspecting the statistics (mean and co-variance) of these estimates. In this paper, we find weighting factors within a Bayesian framework for the used L1/L2 sparsity prior that the resulting maximum a posterior (MAP) estimates do not favor any particular source location. Due to the lack of an analytical...
Topics: Physics, Computational Physics, Medical Physics
Source: http://arxiv.org/abs/1703.09044
Arxiv.org
by Ritayan Roy; Paul C. Condylis; Vindhiya Prakash; Daniel Sahagun; Björn Hessmo
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We report the design and performance of a micro-fabricated conveyor belt for the precise and adiabatic transportation of rubidium (Rb) cold atoms. A theoretical model is presented to determine the least number of conveyor conductors are required as well as for the optimisation of current through them for an adiabatic transportation of atoms. We experimentally demonstrate with as few as three conveyor conductors an adiabatic transportation of $^{87}$Rb cold atoms with minimal loss. This novel...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1704.03030
Quantum-mechanical investigation is presented to study single attosecond pulse generation by gating high-order harmonic emission from H$_2^+$ molecule in intense laser pulses with time-dependent ellipticity. The high-order harmonic generation from H$_2^+$ molecule in superposition of a left and a right-hand circularly polarized Gaussian pulse is studied and the effect of time duration and carrier-envelope phase of laser field on single attosecond pulse generation is investigated. Using laser...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.02888
Arxiv.org
by Christian Seiler; Josef A. Agner; Pierre Pillet; Frédéric Merkt
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Supersonic beams of hydrogen atoms, prepared selectively in Rydberg-Stark states of principal quantum number $n$ in the range between 25 and 35, have been deflected by 90$^\circ$, decelerated and loaded into off-axis electric traps at initial densities of $\approx 10^6$ atoms/cm$^{-3}$ and translational temperatures of 150 mK. The ability to confine the atoms spatially was exploited to study their decay by radiative and collisional processes. The evolution of the population of trapped atoms was...
Topics: Atomic Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.03278
Arxiv.org
by M. Tassi; A. Morphis; K. Lambropoulos; C. Simserides
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We employ Real-Time Time-Dependent Density Functional Theory to study hole oscillations within a B-DNA monomer (one base pair) or dimer (two base pairs). Placing the hole initially at any of the bases which make up a base pair, results in THz oscillations, albeit of negligible amplitude. Placing the hole initially at any of the base pairs which make up a dimer is more interesting: For dimers made of identical monomers, we predict oscillations with frequencies in the range $f \approx$ 20-80 THz,...
Topics: Physics, Chemical Physics, Biological Physics
Source: http://arxiv.org/abs/1704.07413
Extensive information can be obtained on wave-particle interactions and wave fields by direct measurement of perturbed ion distribution functions using laser-induced fluorescence (LIF). For practical purposes, LIF is normally performed on metastable states. If laser intensity is increased to obtain a better LIF signal, then optical pumping produces systematic effects depending on the collision rates which control metastable population and lifetime. We numerically simulate the ion velocity...
Topics: Plasma Physics, Physics, Computational Physics
Source: http://arxiv.org/abs/1704.00242
Arxiv.org
by Jon Drobny; Davide Curreli; Alyssa Hayes; David N. Ruzic
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Fractal TRIDYN (F-TRIDYN) is a modified version of the widely used Monte Carlo, Binary Collision Approximation code TRIDYN that includes an explicit model of surface roughness and additional output modes for coupling to plasma edge and material codes. Surface roughness plays an important role in ion irradiation processes such as sputtering; roughness can significantly increase the angle of maximum sputtering and change the maximum observed sputtering yield by a factor of 2 or more. The complete...
Topics: Plasma Physics, Physics, Computational Physics
Source: http://arxiv.org/abs/1703.00315
Arxiv.org
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The test particle Monte-Carlo models for neutral particles are often used in the tokamak edge modelling codes. The drawback of this approach is that the self-consistent solution suffers from random error introduced by the statistical method. A particular case where the onset of nonphysical solutions can be clearly identified is violation of the global particle balance due to non-converged residuals. There are techniques which can reduce the residuals - such as internal iterations in the code...
Topics: Plasma Physics, Physics, Computational Physics
Source: http://arxiv.org/abs/1703.03733
Arxiv.org
by Ondřej Tkáč; Matija Žeško; Josef Anton Agner; Hansjürg Schmutz; Frédéric Merkt
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A spectroscopic study of Rydberg states of helium ($n$ = 30 and 45) in magnetic, electric and combined magnetic and electric fields with arbitrary relative orientations of the field vectors is presented. The emphasis is on two special cases where (i) the diamagnetic term is negligible and both paramagnetic Zeeman and Stark effects are linear ($n$ = 30, $B \leq$ 120 mT and $F$ = 0 - 78 V/cm ), and (ii) the diamagnetic term is dominant and the Stark effect is linear ($n$ = 45, $B$ = 277 mT and...
Topics: Atomic Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1701.01638
Arxiv.org
by James P. McGilligan; Paul F. Griffin; Rachel Elvin; Stuart J. Ingleby; Erling Riis; Aidan S. Arnold
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We have laser cooled 3$\times10^6$ $^{87}$Rb atoms to 3$\mu$K in a micro-fabricated grating magneto-optical trap (GMOT), enabling future mass-deployment in highly accurate compact quantum sensors. We magnetically trap the atoms, and use Larmor spin precession for magnetic sensing in the vicinity of the atomic sample. Finally, we demonstrate an array of magneto-optical traps with a single laser beam, which will be utilised for future cold atom gradiometry.
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.04150
Arxiv.org
by Theo Cremers; Simon Chefdeville; Niek Janssen; Edwin Sweers; Sven Koot; Peter Claus; Sebastiaan Y. T. van de Meerakker
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We present a new concept for a multi-stage Zeeman decelerator that is optimized particularly for applications in molecular beam scattering experiments. The decelerator consists of a series of alternating hexapoles and solenoids, that effectively decouple the transverse focusing and longitudinal deceleration properties of the decelerator. It can be operated in a deceleration and acceleration mode, as well as in a hybrid mode that makes it possible to guide a particle beam through the decelerator...
Topics: Atomic Physics, Accelerator Physics, Physics
Source: http://arxiv.org/abs/1702.05477
Arxiv.org
by L. Podlecki; R. Glover; J. Martin; T. Bastin
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The mechanical action of light on atoms is nowadays a tool used ubiquitously in cold atom physics. In the semiclassical regime where the atomic motion is treated classically, the computation of the mean force acting on a two-level atom requires in the most general case numerical approaches. Here we show that this problem can be tackled in a pure analytical way. We provide an analytical yet simple expression of the mean force that holds in the most general case where the atom is simultaneously...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.05410
Arxiv.org
by Ronaldo M Evaristo; Antonio M Batista; Ricardo L Viana; Kelly C Iarosz; José D Szezech; Moacir F de Godoy
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The cardiovascular system is composed of the heart, blood and blood vessels. Regarding the heart, cardiac conditions are determined by the electrocardiogram, that is a noninvasive medical procedure. In this work, we propose autoregressive process in a mathematical model based on coupled differential equations in order to model electrocardiogram signals. Our results are compared with experimental tachogram by means of Poincar\'e plot and dentrended fluctuation analysis. We verify that the...
Topics: Physics, Computational Physics, Medical Physics
Source: http://arxiv.org/abs/1703.07383
Arxiv.org
by C. A. Gonzalez; P. Dmitruk; P. D. Mininni; W. H. Matthaeus
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In this paper we analyze the effect of dynamical three-dimensional MHD turbulence on test particle acceleration, and compare how this evolving system affects particle energization by current sheets interaction, against frozen-in-time fields. To do this we analize the ensamble particle acceleration for static electromagnetic fields extracted from direct numerical simulations of the MHD equations, and compare with the dynamical fields. We show that a reduction in particle acceleration in the...
Topics: Plasma Physics, Physics, Space Physics
Source: http://arxiv.org/abs/1704.02642
Arxiv.org
by Shiqian Ding; Gleb Maslennikov; Roland Hablutzel; Dzmitry Matsukevich
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State measurement of a quantum harmonic oscillator is essential in quantum optics and quantum information processing. In a system of trapped ions, we experimentally demonstrate the projective measurement of the state of the ions' motional mode via an effective cross-Kerr coupling to another motional mode. This coupling is induced by the intrinsic nonlinearity of the Coulomb interaction between the ions. We spectroscopically resolve the frequency shift of the motional sideband of the first mode...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.00251
Arxiv.org
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The phenomenological universalities (PU) are extended to include time-depended quantum oscillatory phenomena, coherence and supersymmetry. It will be proved that this approach generates minimum uncertainty coherent states of time-dependent oscillators, which in the dissociation (classical) limit reduce to the functions describing growth (regression) of the systems evolving over time. The results obtained reveal existence of a new class of macroscopic quantum (or quasi-quantum) phenomena, which...
Topics: Biological Physics, Physics, General Physics
Source: http://arxiv.org/abs/1702.00300
Arxiv.org
by Hao Jiang; Guanghan Cao
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A continuous energy transfer method that the boundary condition is no longer needed as the solving prerequisite which will be satisfied spontaneously, is built based on transfer matrix method to solve the eigenfunction of arbitrary energy. This kind of eigenstates is generally divergent, and diverging with informations about convergent states. The divergent state will inevitably reach convergent state by self-tuning and exchanging energy with outside in an efficient and concise way. The...
Topics: Physics, Quantum Physics, Computational Physics
Source: http://arxiv.org/abs/1703.03703
Arxiv.org
by Goulven Quéméner
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This paper deals with the theory of collisions between two ultracold particles with a special focus on molecules. It describes the general features of the scattering theory of two particles with internal structure, using a time-independent quantum formalism. It starts from the Schr\"odinger equation and introduces the experimental observables such as the differential or integral cross sections, and rate coefficients. Using a partial-wave expansion of the scattering wavefunction, the radial...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.09174
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by Michael Swaddle; Lyle Noakes; Liam Salter; Harry Smallbone; Jingbo Wang
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A new method for compiling quantum algorithms is proposed and tested for a three qubit system. The proposed method is to decompose a a unitary matrix U, into a product of simpler U j via a neural network. These U j can then be decomposed into product of known quantum gates. Key to the effectiveness of this approach is the restriction of the set of training data generated to paths which approximate minimal normal subRiemannian geodesics, as this removes unnecessary redundancy and ensures the...
Topics: Physics, Quantum Physics, Computational Physics
Source: http://arxiv.org/abs/1703.10743
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by Dorothea Golze; Niels Benedikter; Marcella Iannuzzi; Jan Wilhelm; Jürg Hutter
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An integral scheme for the efficient evaluation of two-center integrals over contracted solid harmonic Gaussian functions is presented. Integral expressions are derived for local operators that depend on the position vector of one of the two Gaussian centers. These expressions are then used to derive the formula for three-index overlap integrals where two of the three Gaussians are located at the same center. The efficient evaluation of the latter is essential for local...
Topics: Physics, Computational Physics, Chemical Physics
Source: http://arxiv.org/abs/1701.06588
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by Maxence Lepers; Olivier Dulieu
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The term "long-range interactions" refers to electrostatic and magnetostatic potential energies between atoms and molecules with mutual distances ranging from a few tens to a few hundreds Bohr radii. The involved energies are much smaller than the usual chemical bond energies. However, they are comparable with the typical kinetic energies of particles in an ultracold gas ($T\ll 1K$), so that the long-range interactions play a central role in its dynamics. The progress of research...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1703.02833
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Advances in time resolved spectroscopy have provided new insight into the energy transmission in natural photosynthetic complexes. Novel theoretical tools and models are being developed in order to explain the experimental results. We provide a model calculation for the two-dimensional electronic spectra of Cholorobaculum tepidum which correctly describes the main features and transfer time scales found in recent experiments. From our calculation one can infer the coupling of the antenna...
Topics: Physics, Chemical Physics, Biological Physics
Source: http://arxiv.org/abs/1702.06948
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by Yangchao Shen; Joonsuk Huh; Yao Lu; Junhua Zhang; Kuan Zhang; Shuaining Zhang; Kihwan Kim
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Molecules are the most demanding quantum systems to be simulated by quantum computers because of their complexity and the emergent role of quantum nature. The recent theoretical proposal of Huh et al. (Nature Photon., 9, 615 (2015)) showed that a multi-photon network with a Gaussian input state can simulate a molecular spectroscopic process. Here, we report the first experimental demonstration of molecular vibrational spectroscopy of SO$_{2}$ with a trapped-ion system. In our realization, the...
Topics: Atomic Physics, Physics, Optics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1702.04859
We present the results of our calculations of the parity nonconserving electric dipole amplitudes ($E1_{PNC}$) for the $6s ~ ^2S_{1/2} - 5d ~ ^2D_{3/2;5/2}$ transitions of $^{133}$Cs employing a relativistic coupled-cluster (RCC) method. $E1_{PNC}$ values for the nuclear spin independent (NSI) and nuclear spin dependent (NSD) parity non-conservation (PNC) effects for different hyperfine levels of the $6s ~ ^2S_{1/2} - 5d ~ ^2D_{3/2}$ transition and only due to the NSD PNC interaction...
Topics: Atomic Physics, Physics, Optics, Computational Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.04340
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by Angel Garcia-Chung; Daniel Gutiérrez Ruiz; J. David Vergara
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The Dirac's method for constrained systems is applied to the analysis of time-dependent Hamiltonians in the extended phase space. Our analysis provides a conceptually complete description and offers a different point of view of earlier works. We show that the Lewis invariant is a Dirac's observable and in consequence, it is invariant under time-reparametrizations. We compute the Feynman propagator using the extended phase space description and show that the quantum phase of the Feynman...
Topics: Physics, Mathematical Physics, Quantum Physics, Classical Physics, Mathematics
Source: http://arxiv.org/abs/1701.07120
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by S. K. Ruddell; K. E. Webb; I. Herrera; A. S. Parkins; M. D. Hoogerland
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We experimentally demonstrate a ring geometry all-fiber cavity system for cavity quantum electrodynamics with an ensemble of cold atoms. The fiber cavity contains a nanofiber section which mediates atom-light interactions through an evanescent field. We observe well-resolved, vacuum Rabi splitting of the cavity transmission spectrum in the weak driving limit due to a collective enhancement of the coupling rate by the ensemble of atoms within the evanescent field, and we present a simple...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.07413
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by Ville Rimpiläinen; Alexandra Koulouri; Felix Lucka; Jari P Kaipio; Carsten H Wolters
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Knowing the correct skull conductivity is crucial for the accuracy of EEG source imaging, but unfortunately, its true value, which is inter- and intra-individually varying, is difficult to determine. In this paper, we propose a statistical method based on the Bayesian approximation error approach to compensate for source imaging errors related to erroneous skull conductivity. We demonstrate the potential of the approach by simulating EEG data of focal source activity and using the dipole scan...
Topics: Physics, Computational Physics, Medical Physics
Source: http://arxiv.org/abs/1703.09031
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Bell inequalities are usually derived by assuming locality and realism, and therefore violations of the Bell-CHSH inequality are usually taken to imply violations of either locality or realism, or both. But, after reviewing an oversight by Bell, in the Corollary below we derive the Bell-CHSH inequality by assuming only that Bob can measure along vectors b and b' simultaneously while Alice measures along either a or a', and likewise Alice can measure along vectors a and a' simultaneously while...
Topics: Physics, Quantum Physics, General Physics
Source: http://arxiv.org/abs/1704.02876
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by Zhongkai Huang; Lipeng Chen; Nengji Zhou; Yang Zhao
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Following the Dirac-Frenkel time-dependent variational principle, transient dynamics of a one-dimensional Holstein polaron with diagonal and off-diagonal exciton-phonon coupling in an external electric field is studied by employing the multi-D$_2$ {\it Ansatz}, also known as a superposition of the usual Davydov D$_2$ trial states. Resultant polaron dynamics has significantly enhanced accuracy, and is in perfect agreement with that derived from the hierarchy equations of motion method. Starting...
Topics: Physics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.06914
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by Onur Pusuluk; Tristan Farrow; Cemsinan Deliduman; Vlatko Vedral
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Several experimental and theoretical studies report instances of concerted or correlated multiple proton tunneling in solid phases of water. Here, we construct a pseudo-spin model for the quantum motion of protons in a hexameric H$_2$O ring and extend it to open system dynamics that takes environmental effects into account. We approach the problem of correlations in tunneling using quantum information theory in a departure from previous studies. Our results show that one of the principal...
Topics: Physics, Quantum Physics, Chemical Physics
Source: http://arxiv.org/abs/1703.01335
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We present the fully general time-dependent multiconfiguration self-consistent-field method to describe the dynamics of a system consisting of arbitrary different kinds and numbers of interacting fermions and bosons. The total wave function is expressed as a superposition of different configurations constructed from time-dependent spin-orbitals prepared for each particle kind. We derive equations of motion followed by configuration-interaction (CI) coefficients and spin-orbitals for general,...
Topics: Atomic Physics, Physics, Chemical Physics
Source: http://arxiv.org/abs/1704.04583
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Entangled photon pairs-discrete light quanta that exhibit non-classical correlations-play a central role in quantum information and quantum communication technologies. It is a natural demand from technological applications on the intensity of the entangled photon pairs, such that sufficient signal strength can be achieved. Here we propose approaches based on klystron tubes that could potentially achieve stable amplification of the entangled photon pairs generated by spontaneous parametric down...
Topics: Accelerator Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.08477
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by Ye Wang; Mark Um; Junhua Zhang; Shuoming An; Ming Lyu; Jing -Ning Zhang; L. -M. Duan; Dahyun Yum; Kihwan Kim
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A long-time quantum memory capable of storing and measuring quantum information at the single-qubit level is an essential ingredient for practical quantum computation and com-munication. Recently, there have been remarkable progresses of increasing coherence time for ensemble-based quantum memories of trapped ions, nuclear spins of ionized donors or nuclear spins in a solid. Until now, however, the record of coherence time of a single qubit is on the order of a few tens of seconds demonstrated...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1701.04195
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by L. Price; M. Swisdak; J. F. Drake; J. L. Burch; P. A. Cassak; R. E. Ergun
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We present detailed analysis of the turbulence observed in three-dimensional particle-in-cell simulations of magnetic reconnection at the magnetopause. The parameters are representative of an electron diffusion region encounter made by the Magnetospheric Multiscale (MMS) mission. The turbulence is found to develop around both the magnetic x-line and separatrices, is electromagnetic in nature, is characterized by a wavevector $k$ given by $k\rho_e\sim(m_e/m_i)^{0.25}$ with $\rho_e$ the electron...
Topics: Plasma Physics, Physics, Space Physics
Source: http://arxiv.org/abs/1704.01543
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by Santosh Kumar; Haoquan Fan; Harald Kübler; Akbar J. Jahangiri; James P. Shaffer
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Rydberg atom-based electrometry enables traceable electric field measurements with high sensitivity over a large frequency range, from gigahertz to terahertz. Such measurements are particularly useful for the calibration of radio frequency and terahertz devices, as well as other applications like near field imaging of electric fields. We utilize frequency modulated spectroscopy with active control of residual amplitude modulation to improve the signal to noise ratio of the optical readout of...
Topics: Atomic Physics, Physics, Quantum Physics
Source: http://arxiv.org/abs/1702.00494
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by Alexandra Tambova; Mikhail Litsarev; Georgy Guryev; Athanasios G. Polimeridis
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A set of fully numerical algorithms for evaluating the four-dimensional singular integrals arising from Galerkin surface integral equation methods over conforming quadrilateral meshes is presented. This work is an extension of DIRECTFN, which was recently developed for the case of triangular patches, utilizing in a same fashion a series of coordinate transformations together with appropriate integration re-orderings. The resulting formulas consist of sufficiently smooth kernels and exhibit...
Topics: Physics, Computational Physics
Source: http://arxiv.org/abs/1703.08146
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by Henry Keith Moffatt; Krzysztof Andrzej Mizerski
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The relaxation of a helical magnetic field ${\bf B}({\bf x}, t)$ in a high-conductivity plasma contained in the annulus between two perfectly conducting coaxial cylinders is considered. The plasma is of low density and its pressure is negligible compared with the magnetic pressure; the flow of the plasma is driven by the Lorentz force and and energy is dissipated primarily by the viscosity of the medium. The axial and toroidal fluxes of magnetic field are conserved in the perfect-conductivity...
Topics: Plasma Physics, Physics
Source: http://arxiv.org/abs/1703.00708
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Random phase approximation ground state contains electronic configurations where two (and more) identical electrons can occupy the same molecular spin-orbital in apparent violation of the Pauli exclusion principle. This unphysical overcounting of electronic configurations happens due to quasiboson approximation in the treatment of electron-hole pair creation and annihilation operators. We describe the method to restore the Pauli principle in the random phase approximation wavefunction and...
Topics: Physics, Chemical Physics
Source: http://arxiv.org/abs/1702.03395
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by Marcin Witkowski; Bartlomiej Nagoorny; Rodolfo Munoz-Rodriguez; Roman Ciurylo; Piotr Szymon Zuchowski; Slawomir Bilicki; Marcin Piotrowski; Piotr Morzynski; Michal Zawada
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We present a two-species laser cooling apparatus capable of simultaneously collecting Rb and Hg atomic gases into a magneto-optical trap (MOT). The atomic sources, laser system, and vacuum set-up are described. While there is a loss of Rb atoms in the MOT due to photoionization by the Hg cooling laser, we show that it does not prevent simultaneous trapping of Rb and Hg. We also demonstrate interspecies collision-induced losses in the ${}^{87}$Rb-${}^{202}$Hg system.
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1702.04119
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by A. Chen; M. Kübel; B. Bergues; M. F. Kling; A. Emmanouilidou
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A three-dimensional semiclassical model is used to study double ionization of Ar when driven by a near-infrared and near-single-cycle laser pulse for intensities ranging from 0.85$\times$10$^{14}$ W/cm$^{2}$ to 5$\times$10$^{14}$ W/cm$^{2}$. Asymmetry parameters, distributions of the sum of the two electron momentum components along the direction of the polarization of the laser field and correlated momenta are computed as a function of intensity and of the carrier envelope phase. A very good...
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1702.04232
An organism's ability to move freely is a fundamental behaviour in the animal kingdom. To understand animal locomotion requires a characterisation of the material properties, as well as the biomechanics and physiology. We present a biomechanical model of C. elegans locomotion together with a novel finite element method. We formulate our model as a nonlinear initial-boundary value problem which allows the study of the dynamics of arbitrary body shapes, undulation gaits and the link between the...
Topics: Physics, Biological Physics
Source: http://arxiv.org/abs/1702.04988
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by Armen Sargsyan; Aram Papoyan; Ifan G. Hughes; Charles S. Adams; David Sarkisyan
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We have studied the peculiarities of selective reflection from Rb vapor cell with thickness $L $ 2 kG).
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1702.07871
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It is suggested that the observed scale-free correlations of speed fluctuations in flocks of birds are a consequence of the spontaneous breakdown of translational symmetry to a discrete group, and not an indication that the system is near a critical point in phase space. The observed long-range correlation length could then be attributed to the presence of a phonon mode in the flock.
Topics: Physics, Biological Physics
Source: http://arxiv.org/abs/1702.08067
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The ability of the mammalian ear in processing high frequency sounds, up to $\sim$100 kHz, is based on the capability of outer hair cells (OHCs) responding to stimulation at high frequencies. These cells show a unique motility in their cell body coupled with charge movement. With this motile element, voltage changes generated by stimuli at their hair bundles drives the cell body and that, in turn, amplifies the stimuli. In vitro experiments show that the movement of these charges significantly...
Topics: Physics, Biological Physics
Source: http://arxiv.org/abs/1703.05188
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Benchmark reactions involving molecular hydrogen, such as H$_2$+D or H$_2$+Cl, provide the ideal platforms to investigate the effect of Near Threshold Resonances (NTR) on scattering processes. Due to the small reduced mass of those systems, shape resonances due to particular partial waves can provide features at scattering energies up to a few Kelvins, reachable in recent experiments. We explore the effect of NTRs on elastic and inelastic scattering for higher partial waves $\ell$ in the case...
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1703.07913
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Photoionization using attosecond pulses can lead to the formation of coherent superpositions of the electronic states of the parent ion. However, ultrafast electron ejection triggers not only electronic but also nuclear dynamics---leading to electronic decoherence, which is typically neglected on time scales up to tens of femtoseconds. We propose a full quantum-dynamical treatment of nuclear motion in an adiabatic framework, where nuclear wavepackets move on adiabatic potential energy surfaces...
Topics: Physics, Chemical Physics
Source: http://arxiv.org/abs/1703.09462
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by H. Asorey; L. A. Núñez; C. Y. Pérez Arias; S. Pinilla; F. Quiñonez; M. Suárez-Durán
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Incident cosmic ray fluxes over flying aircrafts are compared with those in Bucaramanga, Colombia and very significant differences are observed for proton and neutron fluxes. We also obtained that major contributions in the deposited energy by Cherenkov photons on blood plasma is in the UV-C band.
Topics: Physics, Space Physics
Source: http://arxiv.org/abs/1704.03419
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by Ahmed Khebir; Paweł Dłotko; Bernard Kapidani; Ammar Kouki; Ruben Specogna
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This paper extends the $T$-$\Omega$ formulation for eddy currents based on higher order hierarchical basis functions so that it can deal with conductors of arbitrary topology. To this aim we supplement the classical hierarchical basis functions with non-local basis functions spanning the first de Rham cohomology group of the insulating region. Such non-local basis functions may be efficiently found in negligible time with the recently introduced D{\l}otko--Specogna (DS) algorithm.
Topics: Physics, Computational Physics
Source: http://arxiv.org/abs/1704.03694
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The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. The industrial fabrication of cavities for the European X-Ray Free Electron Laser (XFEL) and the International Linear Collider (ILC) HiGrade Research Project allowed for an investigation of this interplay. For the serial inspection of the inner surface, the optical inspection robot OBACHT was constructed and to analyze the large amount of data, represented in the images of...
Topics: Accelerator Physics, Physics
Source: http://arxiv.org/abs/1704.06080
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The entropy principle in the formulation of M\"{u}ller and Liu is a common tool used in constitutive modelling for the development of restrictions on the unknown constitutive functions describing material properties of various physical continua. In the current work, a symbolic software implementation of the Liu algorithm, based on \verb|Maple| software and the \verb|GeM| package, is presented. The computational framework is used to algorithmically perform technically demanding symbolic...
Topics: Physics, Computational Physics
Source: http://arxiv.org/abs/1704.02292
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Recent studies have introduced a new class of two-dimensional acoustic metamaterials whose dispersion and propagation properties results from the use of geometric inhomogeneities in the form of Acoustic Black Holes (ABH). The ABH is an element able to smoothly bend and slow down elastic waves, therefore providing a variety of unconventional dispersion and propagation properties typically observed in more complex multi-material and locally resonant designs. This approach enables thin-walled...
Topics: Physics, Classical Physics
Source: http://arxiv.org/abs/1701.03445
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Recently, a general expression for Eckart-frame Hamilton operators has been obtained by the gateway Hamiltonian method ({\it J. Chem. Phys.} {\bf 142}, 174107 (2015); {\it ibid.} {\bf 143}, 064104 (2015)). The kinetic energy operator in this general Hamiltonian is nearly identical with that of the Eckart-Watson operator even when curvilinear vibrational coordinates are employed. Its different realizations correspond to different methods of calculating Eckart displacements. There are at least...
Topics: Physics, Chemical Physics
Source: http://arxiv.org/abs/1701.01823
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Synchronizations of processing elements (PEs) in massively parallel simulations, which arise due to communication or load imbalances between PEs, significantly affect the scalability of scientific applications. We have recently proposed a method based on finite-difference schemes to solve partial differential equations in an asynchronous fashion -- synchronization between PEs is relaxed at a mathematical level. While standard schemes can maintain their stability in the presence of asynchrony,...
Topics: Physics, Computational Physics
Source: http://arxiv.org/abs/1702.00496
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We demonstrate how students' use of modeling can be examined and assessed using student notebooks collected from an upper-division electronics lab course. The use of models is a ubiquitous practice in undergraduate physics education, but the process of constructing, testing, and refining these models is much less common. We focus our attention on a lab course that has been transformed to engage students in this modeling process during lab activities. The design of the lab activities was guided...
Topics: Physics Education, Physics
Source: http://arxiv.org/abs/1702.04043
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by S. Schippers; A. L. D. Kilcoyne; R. A. Phaneuf; A. Müller
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The photon-ion merged-beams technique for the photoionization of mass/charge selected ionized atoms, molecules and clusters by x-rays from synchrotron radiation sources is introduced. Examples for photoionization of atomic ions are discussed by going from outer-shell ionization of simple few-electron systems to inner-shell ionization of complex many-electron ions. Fundamental ionization mechanisms are elucidated and the importance of the results for applications in astrophysics and plasma...
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1702.06317
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by Nick Laskin
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A time fractional quantum framework has been introduced into quantum mechanics. A new version of the space-time fractional Schr\"odinger equation has been launched. The introduced space-time fractional Schr\"odinger equation has a new scale parameter, which is a fractional generalization of Planck's constant in quantum physics. It has been shown that the presence of a time fractional time derivative in the space-time fractional Schr\"odinger equation significantly impacts quantum...
Topics: Physics, General Physics
Source: http://arxiv.org/abs/1703.00301
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by Matteo Valerio Falessi
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Predicting the dynamics of a thermonuclear plasma during a magnetic confinement experiment is fundamental in order to make nuclear fusion a reliable source of energy. The development of a set of equations describing the plasma evolution on a given time scale is the main requirement to reach this goal. A limited amount of works have studied in a self-consistent way collisional transport and fluctuation induced transport. The motivation of this work stems from the fundamental importance of the...
Topics: Plasma Physics, Physics
Source: http://arxiv.org/abs/1701.02202
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by Sandip Ghosal; John D. Sherwood
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The screened Coulomb interaction between a pair of infinite parallel planes with spatially varying surface charge is considered in the limit of small electrical potentials for arbitrary Debye lengths. A simple expression for the disjoining pressure is derived in terms of a two dimensional integral in Fourier space. The integral is evaluated for periodic and random charge distributions and the disjoining pressure is expressed as a sum over Fourier-Bloch reciprocal lattice vectors or in terms of...
Topics: Physics, Classical Physics
Source: http://arxiv.org/abs/1702.06815
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An example of the non-equilibrium phase transition is the formation of lanes when one kind of particles is driven against the other. According to experimental observation, lane formation in binary complex plasmas occurs when the smaller particles are driven through the stationary dust cloud of the larger particles. We calculate the driving force acting on a probe particle that finds itself in a quiescent cloud of particles in complex plasma of the low-pressure radio frequency discharge under...
Topics: Plasma Physics, Physics
Source: http://arxiv.org/abs/1703.05789
A simple junior-level electrodynamics problem is used to illustrate the interference between a source-free standing plane wave and a wave generated by a pulse in a current sheet. Depending upon the relative phases between the standing wave and the current pulse and also upon the relative magnitudes, we can find quite different patterns of emitted energy and momentum. If the source gives a large radiation pulse so that the source-free plane wave can be neglected, then the radiation spreads out...
Topics: Physics, Classical Physics
Source: http://arxiv.org/abs/1703.06309
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by Kai Huang
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The Bayreuth Festspielhaus is well known for its architecture because its design is heavily influenced by composer Richard Wagner. Due to the special acoustic design, the reverberation time (i.e., time scale for the sound pressure level to decay $60$~dB) is larger than usual opera houses. Using hand-claps and smart phone recordings, I measured the impulse response of the Bayreuth Festspielhaus in the auditorium, on the stage, as well as in the orchestra pit. The measured reverberation time...
Topics: Physics, Popular Physics
Source: http://arxiv.org/abs/1703.07080
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by Tim Gould; Sébastien Lebègue; János G. Ángyán; Tomáš Bučko
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By explicitly including fractionally ionic contributions to the polarizability of a many-component system we are able to significantly improve on previous atom-wise many-body van der Waals approaches with essentially no extra numerical cost. For non-ionic systems our method is comparable in accuracy to existing approaches. However, it offers substantial improvements in ionic solids, e.g. producing better polarizabilities by over 65% in some cases. It has particular benefits for two-dimensional...
Topics: Physics, Chemical Physics
Source: http://arxiv.org/abs/1703.08786
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by Irina Barzykina
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A physical model is developed, which suggests a pathway to determining the optimal release conditions for a basketball free throw. Theoretical framework is supported by Monte Carlo simulations and a series of free throws performed and analysed at Southbank International School. The model defines a smile-shaped success region in angle-velocity space where a free throw will score. A formula for the minimum throwing angle is derived analytically. The optimal throwing conditions are determined...
Topics: Physics, Popular Physics
Source: http://arxiv.org/abs/1702.07234
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by Herman Telkamp
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It is argued that many of the problems and ambiguities of standard cosmology derive from a single one: violation of the conservation of energy in the standard paradigm. From a relational expression of the kinetic energy between two particles, due to Schroedinger, one can derive a Machian energy equation of the expanding Universe [1], which in fact is the Friedmann equation. It turns out that conservation of total Machian energy has some intriguing consequences. It yields a set of only four...
Topics: Physics, General Physics
Source: http://arxiv.org/abs/1703.06013
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by A. A. Mihajlov; Lj. M. Ignjatovic; V. A. Sreckovic
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Within the problem of the finding of the mean potential energy of the charged particle in the plasma in this work a classification of physical systems (electrolytes, dusty plasmas, plasmas) is made based on consideration, or lack thereof, of a few special additional conditions. The system considered here, as well as other systems which are described with those additional conditions imposed are treated as the systems of the "closed" type, while the systems where those conditions are...
Topics: Plasma Physics, Physics
Source: http://arxiv.org/abs/1703.07613
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by Sabine Auer; Florian Steinke; Wang Chunsen; Andrei Szabo; Rudolf Sollacher
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Power generation in Germany is currently transitioning from a system based on large, central, thermal power plants to one that heavily relies on small, decentral, mostly renewable power generators. This development poses the question how transmission grids' reactive power demand for voltage management, covered by central power plants today, can be supplied in the future. In this work, we estimate the future technical potential of such an approach for the whole of Germany. For a 100% renewable...
Topics: Applied Physics, Physics
Source: http://arxiv.org/abs/1704.06568
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by Azer Trimeche; Mehdi Langlois; Sébastien Merlet; Franck Pereira dos Santos
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Wavefront aberrations are identified as a major limitation in quantum sensors. They are today the main contribution in the uncertainty budget of best cold atom interferometers based on two-photon laser beam splitters, and constitute an important limit for their long-term stability, impeding these instruments from reaching their full potential. Moreover, they will also remain a major obstacle in future experiments based on large momentum beam splitters. In this article, we tackle this issue by...
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1704.07088
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by Hyok Sang Han; Hyun Gyung Lee; Seokchan Yoon; Donghyun Cho
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We demonstrate in situ fluorescence detection of $^7$Li atoms in a 1D optical lattice with single atom precision. Even though illuminated lithium atoms tend to boil out, when the lattice is deep, molasses beams without extra cooling retain the atoms while producing sufficient fluorescent photons for detection. When the depth of the potential well at an antinode is 2.4 mK, an atom remains trapped for 30 s while scattering probe photons at the rate of $1.7 \times 10^5$ s$^{-1}$. We propose a...
Topics: Atomic Physics, Physics
Source: http://arxiv.org/abs/1703.07084
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by I. Agapov; G. Geloni; S. Tomin; I. Zagorodnov
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Existing FEL facilities often suffer from stability issues: so electron orbit, transverse electron optics, electron bunch compression and other parameters have to be readjusted often to account for drifts in performance of various components. The tuning procedures typically employed in operation are often manual and lengthy. We have been developing a combination of model-free and model-based automatic tuning methods to meet the needs of present and upcoming XFEL facilities. Our approach has...
Topics: Accelerator Physics, Physics
Source: http://arxiv.org/abs/1704.02335