Dissipative solitons which cannot be trapped

In this paper we study the behavior of dissipative solitons in systems with high order nonlinear dissipation and show how they cannot survive under the effect of trapping potentials both of rigid wall type or asymptotically increasing ones. This provides an striking example of a soliton which cannot be trapped and only survives to the action of a weak potential

Non-Equilibrium Dynamics and Weakly Broken Integrability

Motivated by dynamical experiments on cold atomic gases, we develop a quantum kinetic approach to weakly perturbed integrable models out of equilibrium. Using the exact matrix elements of the underlying integrable model we establish an analytical approach to real-time dynamics. The method addresses a broad range of timescales, from the intermediate regime of pre-thermalization to late-time thermalization. Predictions are given for the time-evolution of physical quantities, including effective temperatures and thermalization rates. The approach provides conceptual links between perturbed quantum many-body dynamics and classical Kolmogorov-Arnold-Moser (KAM) theory. In particular, we identify a family of perturbations which do not cause thermalization in the weakly perturbed regime.Comment: v4: Improved discussion of perturbed Lieb-Liniger model and interactions. 5+10 pages, 3+7 figures. v3: New discussion of perturbed Lieb-Liniger model, mentioned in text and new section in SM. 5+10 pages, 3+7 figures. v2: references added and discussion of nearly-integrable perturbations improved. 5+9 pages, 3+5 figure

Generation of the second-harmonic Bessel beams via nonlinear Bragg diffraction

We generate conical second-harmonic radiation by transverse excitation of a two-dimensional annular periodically-poled nonlinear photonic structure with a fundamental Gaussian beam. We show that these conical waves are the far-field images of the Bessel beams generated in a crystal by parametric frequency conversion assisted by nonlinear Bragg diffraction.Comment: 4 pages, 5 figures. submitte

Plague, Crisis, and Scientific Authority during the London Caterpillar Outbreak of 1782

This is the final version. Available on open access from Cambridge University Press via the DOI in this recordIn the summer of 1780, anti-Catholic riots led by Lord George Gordon in London left hundreds dead and stretches of the city burnt and destroyed. Eighteen months later, during a tense period in the city's history, London was invaded by brown-tail moth caterpillars. The metropolis and surrounding countryside disappeared behind the tents and nests of the insects, prompting widespread fear of famine and plague. With the memory of the riots still fresh, philanthropists such as Jonas Hanway and entomologists like William Curtis sought to assuage the public's fear, insisting that the brown-tail moth outbreak was part of the normal operations of nature, that the infestation bore no danger to the public, and that efforts to alarm the public or describe them as dangerous were contemptuous. At the same time, the conjurer and philosopher Gustavus Katterfelto, performing in the city, sought to profit from the public agitation, developing spectacles and performances that promised the insects would soon deliver famine, plague, and ruin on the city. This article examines the intersection of scientific authority, public fear, and performance, showing that the outbreak placed tremendous stress on the relationship between scientific authority and security in the metropolis

Long Distance Transport of Ultracold Atoms using a 1D optical lattice

We study the horizontal transport of ultracold atoms over macroscopic distances of up to 20 cm with a moving 1D optical lattice. By using an optical Bessel beam to form the optical lattice, we can achieve nearly homogeneous trapping conditions over the full transport length, which is crucial in order to hold the atoms against gravity for such a wide range. Fast transport velocities of up to 6 m/s (corresponding to about 1100 photon recoils) and accelerations of up to 2600 m/s2 are reached. Even at high velocities the momentum of the atoms is precisely defined with an uncertainty of less than one photon recoil. This allows for construction of an atom catapult with high kinetic energy resolution, which might have applications in novel collision experiments.Comment: 15 pages, 8 figure

Entangled Bessel beams

Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Having a readily adjustable radial scale, BG modes provide a more favourable basis for OAM entanglement over Laguerre-Gaussian (LG) modes. The OAM bandwidth in terms of BG modes can be increased by selection of particular radial modes and leads to a flattening of the spectrum. The flattening of the spectrum allows for higher entanglement. We demonstrate increased entanglement in terms of BG modes by performing a Bell-type experiment and violating the appropriate Clauser Horne Shimony Holt (CHSH) inequality. In addition, we reconstruct the quantum state of BG modes entangled in high-dimensions.Comment: 8 pages, 4 figure

Biochemical adaptations in early starvation: observations on sex difference.

Twenty-two students, eleven male and eleven female, volunteered to fast for 3 d. Twenty-four hour urine collections were obtained over the period of study, and total nitrogen, urea, and 3-hydroxybutyrate (3-OH-butyrate) were determined in each

A New Concept for a Laser-Based Ultrasonic Phased Array Receiver Using Photo-emf Detection

The virtues of laser-based ultrasound [1], LBU, in general, and phased-array generation and detection in particular, have been appreciated for many years. The ability to improve the spatial resolution of an imaging system, coupled with the potential reduction in local laser intensity at a given location on a component to avoid surface damage while still realizing enhanced performance, represent but two motivating factors that have driven the community to seek methods by which to realize phased-array processing. There has been much activity in demonstrating that phased-array generation of ultrasound can lead to an enhanced directivity of the ultrasound as well as to a decrease (or, increase) in the bandwidth of the generated ultrasound (if desired), be it in the bulk or along the surface of components. Examples of such phased-array generationtechniques (either in the thermoelastic or ablative regimes) include illumination of several discrete spots or locus of points with pulsed lasers [1] on the surface of a workpiece (simultaneously or sequentially), be it a line, an annular ring, or a plurality of spots — or illumination of a scanning pattern of lines along the surface of a sample, the so-called phase-velocity scanning technique [2]. By extension of the phased-array generation concept, one is led to consider the notion of laser-based, phased-array detectionof ultrasound [3]. By reciprocity, this can lead to a receiver of higher resolution relative to a single location for the optical sensing of the ultrasound, as well as to a reduction in the local laser fluence required to achieve a given spatial performance. Moreover, one can, in principle, combine the two modes of phased-array excitation and detection to realize even greater resolution capabilities, which one may refer to as “product processing.” In this case, one has, in essence, a focusing transmitter and an imaging detector, both functioning in concert

Diffraction-free beams in thin films

The propagation and transmission of Bessel beams through nano-layered structures has been discussed recently. Within this framework we recognize the formation of unguided diffraction-free waves with the spot size approaching and occasionally surpassing the limit of a wavelength when a Bessel beam of any order n is launched onto a thin material slab with grazing incidence. Based on the plane-wave representation of cylindrical waves, a simple model is introduced providing an exact prescription of the transverse pattern of this type of diffraction-suppressed localized waves. Potential applications in surface science are put forward for consideration