The disease that remains reconstruction of the wasteland mythin ian mcewan’s machines like me

En las letras inglesas, el mito de la Tierra Baldía, célebre sobre todo por su inscripción en las narrativas del ciclo artúrico, se convirtió en un claro ejemplo de mito con un gran peso moral. Y, como todo mito, la Tierra Baldía ha evolucionado y el Grial que la restituiría en paraíso, ha abandona la función curativa y se convierte en un imposible. En Machines Like Me ( Charlie hace frente a la adopción de un androide, Adam, que desde el comienzo se definirá como «el Grial de la Ciencia» y que, poco a poco, adquirirá un comportamiento más humano que el de su padre adoptivo. Las frustraciones de Charlie y la consecuente devastación de su vida personal, con Adam como eje motor, le embarcarán en la búsqueda de su propio paraíso en una Tierra Baldía asol ada por la guerra de las Malvinas, donde Reino Unido será derrotado.In British literature, the Wasteland myth, famous due to its appearance in the Arthurian cycle, became a clear example of myth with great moral content. And like all myths, the Wasteland has evolved and the Grail, which would restore it to paradise, has ab andoned the curative function and became unattainable. In Machines Like Me ( Charlie faces the adoption of an android, Adam, who from the beginning will be defined as « the Grail of Science » and who will gradually acquire a more human behaviour than t hat of his adoptive father. Charlie’s frustrations and the consequent devastation of his personal life, with Adam as the driving force, will embark him on the search for his paradise in a Wasteland ravaged by the Falklands war, where the United Kingdom wil l be defeated

Scalable sub-cycle pulse generation by soliton self-compression in hollow capillary fibers with a decreasing pressure gradient

Advances in the generation of the shortest optical laser pulses down to the sub-cycle regime promise to break new ground in ultrafast science. In this work, we theoretically demonstrate the potential scaling capabilities of soliton self-compression in hollow capillary fibers with a decreasing pressure gradient to generate near-infrared sub-cycle pulses in very different dispersion and nonlinearity landscapes. Independently of input pulse, gas and fiber choices, we present a simple and general route to find the optimal self-compression parameters which result in high-quality pulses. The use of a decreasing pressure gradient naturally favors the self-compression process, resulting in shorter and cleaner sub-cycle pulses, and an improvement in the robustness of the setup when compared to the traditional constant pressure approach

Influence of the spatial confinement on the self-focusing of ultrashort pulses in hollow-core fibers

The collapse of a laser beam propagating inside a hollow-core fiber is investigated by numerically solving different nonlinear propagation models. We have identified that the fiber confinement favors the spatial collapse, especially in case of pulses with the input peak power close to the critical value. We have also observed that when using pulses in the femtosecond range, the temporal dynamics plays an important role, activating the spatial collapse even for pulses with input peak powers below the critical value. The complex self-focusing dynamics observed in the region below the critical power depends on the temporal evolution of the pulse and, also, on the interaction between the different spatial modes of the hollow-core fiber.The authors thank support from Spanish Ministerio de Economía y Competitividad (FIS2016-75652-P) and from Junta de Castilla y León (SA287P18). A.C. is funded by the FPI grant program of Spanish Ministerio de Economía y Competitividad and European Social Fund (BES-2017-080280)

Extreme ultraviolet fractional orbital angular momentum beams from high harmonic generation

We investigate theoretically the generation of extreme-ultraviolet (EUV) beams carrying fractional orbital angular momentum. To this end, we drive high-order harmonic generation with infrared conical refraction (CR) beams. We show that the high-order harmonic beams emitted in the EUV/soft x-ray regime preserve the characteristic signatures of the driving beam, namely ringlike transverse intensity profile and CR-like polarization distribution. As a result, through orbital and spin angular momentum conservation, harmonic beams are emitted with fractional orbital angular momentum, and they can be synthesized into structured attosecond helical beams –or “structured attosecond light springs”– with rotating linear polarization along the azimuth. Our proposal overcomes the state of the art limitations for the generation of light beams far from the visible domain carrying non-integer orbital angular momentum and could be applied in fields such as diffraction imaging, EUV lithography, particle trapping, and super-resolution imaging

Ultrashort Extreme Ultraviolet Vortices

Optical vortices are very attractive because they transport a well-defined orbital angular momentum (OAM) associated with the singularity of the beam. These singular beams, commonly generated in the optical regime, are used in a wide range of applications: communication, micromanipulation, microscopy, among others. The production of OAM beams in the extreme ultraviolet (XUV) and X-ray regimes is of great interest as it allows to extend the applications of optical vortices down to the nanometric scale. Several proposals have been explored in order to generate XUV vortices in synchrotrons and FEL facilities. Here, we study the generation of XUV vortices through high-order harmonic generation (HHG). HHG is a unique source of coherent radiation extending from the XUV to the soft X-ray regime, emitted in the form of attosecond pulses. When driving HHG by OAM beams, highly charged XUV vortices with unprecedented spatiotemporal properties are emitted in the form of helical attosecond beams. In this chapter, we revise our theoretical work in the generation of XUV vortices by HHG. In particular, we illustrate in detail the role of macroscopic phase matching of high-order harmonics when driven by OAM beams, which allows to control the production of attosecond beams carrying OAM

Optimization of pulse self-compression in hollow capillary fibers using decreasing pressure gradients

The improvement of techniques for the generation of near-infrared (NIR) few-cycle pulses is paving the way for new scenarios in time-resolved spectroscopy and the generation of ultrashort extreme-ultraviolet pulses through high-harmonic generation. In this work, we numerically study how to optimize the self-compression of NIR pulses using decreasing pressure gradients in hollow capillary fibers (HCFs). We identify a moderate nonlinear regime in which sub-cycle pulses are obtained with very good temporal quality from an input 30 fs pulse centered at a 800 nm wavelength and coupled as the fundamental mode of an argon-filled HCF fully evacuated at the output end. Surprisingly, we observe that there is a relatively broad region of parameters for which the optimum self-compression takes place, defined by a simple relation between the input pulse energy and the initial gas pressure.This work was supported by grant PID2019-106910GB-I00, funded by the Spanish Ministry of Science and Innovation, MCIN/AEI/ 10.13039/501100011033

Tools for numerical modelling of nonlinear propagation in hollow capillary fibres and their application.

[EN]The development of new coherent and ultrashort light sources is of great relevance for exploring fundamental processes and different applications in science. The most successful technique for generating ultrashort laser pulses, in terms of energy and pulse duration, is using hollow capillary fibre (HCF) compressors. The different strategies to further increase the pulse energy and to achieve shorter pulses at non-conventional wavelengths, lead to continuous improvement of this technique. In this work, we present the theoretical framework of the nonlinear propagation in HCFs through the propagation equation and the spatio-temporal effects that appear in the nonlinear dynamics. To numerically study the nonlinear propagation of the pulse in the HCF, we present different numerical models considering only the spatial effects, (1 + 1)D model, the full spatio-temporal dynamics and ionization, (2 + 1)D model, or the case with lack of cylindrical symmetry, (3 + 1)D model. To show the performance of some of these models in a particular case, we study the generation of ultrashort and energetic dispersive waves (DWs) inside the HCF. We show that the emission of a DW at a fixed wavelength for different pump wavelengths is possible by parameter scaling

Nonperturbative Twist in the Generation of Extreme-Ultraviolet Vortex Beams

High-order harmonic generation (HHG) has been recently proven to produce extreme-ultraviolet (XUV) vortices from the nonlinear conversion of infrared twisted beams. Previous works have demonstrated a linear scaling law of the vortex charge with the harmonic order. We demonstrate that this simple law hides an unexpectedly rich scenario for the buildup of orbital angular momentum (OAM) due to the nonperturbative behavior of HHG. The complexity of these twisted XUV beams appears only when HHG is driven by nonpure vortex modes, where the XUV OAM content is dramatically increased. We explore the underlying mechanisms for this diversity and derive a general conservation rule for the nonperturbative OAM buildup. The simple scaling found in previous works corresponds to the collapse of this scenario for the particular case of pure (single-mode) OAM driving fields.C.H.-G. acknowledges support by a Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007–2013), under REA Grant Agreement No. 328334. We acknowledge support from Junta de Castilla y León (Projects No. SA116U13 and No. SA046U16) and Ministerio de Economía y Competitividad (FIS2013-44174- P, FIS2016-75652-P). A. P. acknowledges support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division under Contract No. DE-AC02- 06CH11357

Ultrashort visible energetic pulses generated by nonlinear propagation of necklace beams in capillaries

The generation of ultrashort visible energetic pulses is investigated numerically by the nonlinear propagation of infrared necklace beams in capillaries. We have developed a (3+1)D model that solves the nonlinear propagation equation, including the complete spatio-temporal dynamics and the azimuthal dependence of these structured beams. Due to their singular nonlinear propagation, the spectrum broadening inside the capillary extends to the visible region in a controlled way, despite the high nonlinearity, avoiding self-focusing. The results indicate that the features of these necklace beams enable the formation of visible pulses with pulse duration below 10 fs and energies of 50 μJ by soliton self-compression dynamics for different gas pressures inside the capillary.Junta de Castilla y León (SA287P18); Ministerio de Economía y Competitividad (BES-2017-080280, FIS2016-75652-P); Ministerio de Ciencia e Innovación (PID2019-106910GB-I00)

Attosecond twisted beams from high-order harmonic generation driven by optical vortices

Optical vortices are structures of the electromagnetic field with a spiral phase ramp about a point-phase singularity, carrying orbital angular momentum (OAM). Recently, OAM has been imprinted to short-wavelength radiation through high-order harmonic generation (HHG), leading to the emission of attosecond twisted beams in the extreme-ultraviolet (XUV) regime. We explore the details of the mapping of the driving vortex to its harmonic spectrum. In particular, we show that the geometry of the harmonic vortices is convoluted, arising from the superposition of the contribution from the short and long quantum paths responsible of HHG. Finally, we show how to take advantage of transverse phase-matching to select twisted attosecond beams with different spatiotemporal properties.C.H.-G. acknowledges support from the Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007–2013), under REA grant Agreement No. 328334. The authors acknowledge support from Junta de Castilla y León (Projects SA116U13, SA046U16) and MINECO (Projects FIS2013-44174-P, FIS2016-75652-P). A.P. acknowledges support from the US Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division under the contract no. DE-AC02-06CH11357 and support from the European Unions Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 702565