Split-sideband spectroscopy in slowly modulated optomechanics

Optomechanical coupling between the motion of a mechanical oscillator and a cavity represents a new arena for experimental investigation of quantum effects on the mesoscopic and macroscopic scale.The motional sidebands of the output of a cavity offer ultra-sensitive probes of the dynamics. We introduce a scheme whereby these sidebands split asymmetrically and show how they may be used as experimental diagnostics and signatures of quantum noise limited dynamics. We show split-sidebands with controllable asymmetry occur by simultaneously modulating the light-mechanical coupling $g$ and $\omega_M$ - slowly and out of-phase. Such modulations are generic but already occur in optically trapped set-ups where the equilibrium point of the oscillator is varied cyclically. We analyse recently observed, but overlooked, experimental split-sideband asymmetries; although not yet in the quantum regime, the data suggests that split sideband structures are easily accessible to future experiments

Cavity cooling a single charged nanoparticle

The development of laser cooling coupled with the ability to trap atoms and ions in electromagnetic fields, has revolutionised atomic and optical physics, leading to the development of atomic clocks, high-resolution spectroscopy and applications in quantum simulation and processing. However, complex systems, such as large molecules and nanoparticles, lack the simple internal resonances required for laser cooling. Here we report on a hybrid scheme that uses the external resonance of an optical cavity, combined with radio frequency (RF) fields, to trap and cool a single charged nanoparticle. An RF Paul trap allows confinement in vacuum, avoiding instabilities that arise from optical fields alone, and crucially actively participates in the cooling process. This system offers great promise for cooling and trapping a wide range of complex charged particles with applications in precision force sensing, mass spectrometry, exploration of quantum mechanics at large mass scales and the possibility of creating large quantum superpositions.Comment: 8 pages, 5 figures Updated version includes additional references, new title, and supplementary information include

Conditions for the onset of the current filamentation instability in the laboratory

Current Filamentation Instability (CFI) is capable of generating strong magnetic fields relevant to explain radiation processes in astrophysical objects and lead to the onset of particle acceleration in collisionless shocks. Probing such extreme scenarios in the laboratory is still an open challenge. In this work, we investigate the possibility of using neutral $e^{-}$ $e^{+}$ beams to explore the CFI with realistic parameters, by performing 2D particle-in-cell simulations. We show that CFI can occur unless the rate at which the beam expands due to finite beam emittance is larger than the CFI growth rate and as long as the role of competing electrostatic two-stream instability (TSI) is negligible. We also show that the longitudinal energy spread, typical of plasma based accelerated electron-positron fireball beams, plays a minor role in the growth of CFI in these scenarios

Slow down of a globally neutral relativistic e−e+e^-e^+ beam shearing the vacuum

The microphysics of relativistic collisionless sheared flows is investigated in a configuration consisting of a globally neutral, relativistic $e^-e^+$ beam streaming through a hollow plasma/dielectric channel. We show through multidimensional PIC simulations that this scenario excites the Mushroom instability (MI), a transverse shear instability on the electron-scale, when there is no overlap (no contact) between the $e^-e^+$ beam and the walls of the hollow plasma channel. The onset of the MI leads to the conversion of the beam's kinetic energy into magnetic (and electric) field energy, effectively slowing down a globally neutral body in the absence of contact. The collisionless shear physics explored in this configuration may operate in astrophysical environments, particularly in highly relativistic and supersonic settings where macroscopic shear processes are stable

Micromechanisms of inelastic deformation in sandstones: An insight using x-ray micro-tomography

This study investigates the grain-scale mechanisms that lead to failure by strain localisation in specimens of Fontainebleau sandstone with different degrees of cementation. While the effects of inter-particle bonding on the mechanical behaviour of granular geomaterials, including soft rocks, have been largely studied, the physical micro-scale mechanisms governing the material deformation are still poorly understood. In this study, laboratory techniques have been developed to allow a non-invasive investigation of the internal deformation of sandstones during triaxial compression to failure. The material investigated was Fontainebleau sandstone, a quartzite formation from the Paris basin (France), which can be found as very hard, tightly cemented sandstone or more porous and less cemented material. Specimens with porosities of 6 and 21% were investigated. Triaxial compression tests at confining pressures of 2 and 7 MPa were conducted on dry cylindrical specimens of 11 mm diameter and 22 mm height. Three-dimensional (3D) images of the full specimens were obtained by carrying out x-ray micro-tomography scans at key points throughout the test. The high-resolution 3D tomographic images have a voxel size of 8.5 μm (0.033d50), allowing clear identification of the grains. This analysis suggests that dilatancy of the material, which depends on the degree of bonding between grains, plays a fundamental role in the failure mode of granular media. Insights into bonding rupture mechanisms and grain damage by inter- and intra-granular cracking are presented

An experimental study of micro-scale deformation in a soft sandstone

This study investigates the grain scale mechanisms that lead to failure by strain localisation in a slightly cemented sandstone. While the effects of interparticle bonding on the mechanical behaviour of granular geomaterials, including soft rocks, have been largely studied, the physical micro-scale mechanisms governing the material deformation are still poorly understood. In this study, laboratory techniques have been developed to allow a non-invasive investigation of the internal deformation of a soft sandstone during triaxial compression to failure. The material studied is Fontainebleau sandstone, a quartzite formation from the Paris Basin, with a porosity of 21 %. Fontainebleau sandstone is a uniformly graded material with a mean grain size of 260 m. Triaxial compression tests at confining pressures of 2 MPa and 7 MPa were conducted on dry cylindrical specimens of 11 mm diameter by 22 mm height. Three-dimensional images of the full specimen were obtained by carrying out x-ray micro-tomography scans at key points throughout the test. The high-resolution tomographic images have a voxel size of 8.5 m (0.033d50) allowing a clear identification of the grains. A preliminary analysis has suggested that the failure mechanisms can be different for the samples tested at different confining pressures, which has a direct implication on the permeability of the material

Caracterización y Tipificación De La Cadena Agroproductiva Del Cultivo De Maracuyá (passiflora edulis L) Pedernales, Manabí, Ecuador/Characterization and Typification of the Agroproductive Chain of Maracuya Cultivation (passiflora edulis L) Pedernales, M

La cadena agroproductiva de maracuyá (passiflora edulis L), se desarrolla en la costa ecuatoriana, destacando la calidad de producto en sus dos variedades amarilla y roja. El objetivo de esta investigación es realizar la caracterización y tipificación, analizando aspectos agroproductivos, socioeconómicos y comercio en las parroquias 10 de Agosto, Atahualpa y Cojimíes pertenecientes al cantón Pedernales, en cual cuenta con 266 productores de Maracuyá, abarcando una extensión de 532 hectáreas, la muestra constituye 20 fincas productoras, aplicando la metodología exploratoria, descriptiva y analítica, de evaluación insitú, obteniendo que el género masculino es el predominante en el manejo y responsabilidad de finca (100%), (90%) residen en la finca, cuentan con un nivel de estudios mayormente de escolaridad (75%), nivel sociorganizativo (15%) pertenecen alguna organización constituida legalmente, la tenencia de tierra representa un (25%) 1 - 5 ha, (25%) más de 26 ha, (20%) 6 - 10 ha, (15%) 11 - 15 ha y (15%) 16 - 25 ha, utilizan mano de obra adicional (40%), el tipo agricultura (90%) convencional, (10%) manejo orgánico, (55%), posee más de 3 cultivos en producción, ocupando el (75%) agua de rio, un (50%) realizan riego por surcos, la producción anual en Cojimíes representa (19 ha), con 27000 kg/ano, 10 de agosto (14 ha), con 24200 kg/año, Atahualpa (6 ha), con 5900 kg/año, el (74%) cultiva la variedad amarillo, (26%) variedad rojo morado, (100%) realizan actividades de pos cosecha el (85%) los ingresos mensuales provienen de agricultura (75%), (20%) crianza de animales; y (5%) del comercio. The agro-productive chain of passion fruit (passiflora edulis L), is developed on the Ecuadorian coast, highlighting the quality of the product in its two yellow and red varieties. The objective of this research is to characterize and typify, analyzing agroproductive, socioeconomic and trade aspects in the parishes 10 de Agosto, Atahualpa and Cojimíes belonging to the canton Pedernales, which has 266 Maracuyá producers, covering an area of 532 hectares, the sample constitutes 20 producing farms, applying the exploratory, descriptive and analytical methodology, of insitu evaluation, obtaining that the masculine gender is the predominant one in the management and responsibility of the farm (100%), (90%) they reside in the farm, they count With a level of education mostly of schooling (75%), socio-organizational level (15%) belong some legally constituted organization, land ownership represents one (25%) 1 - 5 ha, (25%) more than 26 ha, (20%) 6 - 10 ha, (15%) 11 - 15 ha and (15%) 16 - 25 ha, use additional labor (40%), the agriculture type (90%) conventional, (10%) management organic, (55%), owns more than 3 crops in production, occupying (75%) river water, one (50%) irrigate by furrows, the annual production in Cojimies represents (19 ha), with 27000 kg / year, August 10 (14 ha), with 24200 kg / year, Atahualpa (6 ha), with 5900 kg / year, (74%) cultivates the yellow variety, (26%) purple red variety, (100%) carry out post-harvest activities (85%) the monthly income comes from agriculture (75%), (20%) raising animals; and (5%) of commerce. Palabras clave: Caracterización, Tipificación, Cadena, Agro productiva, Maracuyá. Keywords: Characterization, Typification, chain, agro productive, passion fruit

Electron trapping and acceleration by the plasma wakefield of a self-modulating proton beam

It is shown that co-linear injection of electrons or positrons into the wakefield of the self-modulating particle beam is possible and ensures high energy gain. The witness beam must co-propagate with the tail part of the driver, since the plasma wave phase velocity there can exceed the light velocity, which is necessary for efficient acceleration. If the witness beam is many wakefield periods long, then the trapped charge is limited by beam loading effects. The initial trapping is better for positrons, but at the acceleration stage a considerable fraction of positrons is lost from the wave. For efficient trapping of electrons, the plasma boundary must be sharp, with the density transition region shorter than several centimeters. Positrons are not susceptible to the initial plasma density gradient.Comment: 9 pages, 9 figures, 1 table, 44 reference