arXiv subjects

Antonio Picón

Publications and source records attributed to Antonio Picón.

26 records · Page 2Linked to original sources

arXiv2015

Optically-dressed resonant Auger processes induced by high-intensity x rays

We have unveiled coherent multiphoton interferences originating from different quantum paths taken by the Auger electron induced by a high-intensity x-ray/XUV pulse under the presence of a strong optical field. These interferences give rise to a clear signature in the angle-resolved Auger electron spectrum: an asymmetry with respect to the energy of the Auger decay channel. In order to illustrate this effect we have considered the resonant Auger decay of the transition $2p^{5} \!\leftrightarrow\! 1s^{-1}2p^{6}$ in Ne$^{+}$. The simulations show that these interferences are very sensitive to the parameters of the x-ray and optical fields.

quant-ph↗

arXiv2013

Optical control of resonant Auger processes

We theoretically show that core-excited state populations can be efficiently manipulated with strong optical fields during their decay, which takes place in a few femtoseconds. We focus on the $1s^{-1}3p$ resonant excitation in neon, where the $1s^{-1}3p$ and $1s^{-1}3s$ core-excited states are coupled by an optical field. By analyzing the Auger electron spectrum we observe the inner-shell population transfer induced by the optical coupling. We also show that the angular anisotropy of the Auger electron is imprinted in the multipeak structure induced by the optical-dressed continuum, namely sidebands.

physics.optics↗

arXiv2011

Spin and Orbital angular momentum propagation in anisotropic media: theory

This paper is devoted to study the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with a general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing the space-variant-optical-axis phase plates.

physics.optics↗

arXiv2010

Atomtronics with holes: Coherent transport of an empty site in a triple well potential

We investigate arrays of three traps with two fermionic or bosonic atoms. The tunneling interaction between neighboring sites is used to prepare multi-site dark states for the empty site, i.e., the hole, allowing for the coherent manipulation of its external degrees of freedom. By means of an ab initio integration of the Schrödinger equation, we investigate the adiabatic transport of a hole between the two extreme traps of a triple-well potential. Furthermore, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to get physical insight into the transport process. Finally, we discuss the use of the hole for the construction of a coherent single hole diode and a coherent single hole transistor.

quant-ph↗

arXiv2010

Transferring orbital and spin angular momenta of light to atoms

Light beams carrying orbital angular momentum, such as Laguerre-Gaussian beams, give rise to the violation of the standard dipolar selection rules during the interaction with matter yielding, in general, an exchange of angular momentum larger than hbar per absorbed photon. By means of ab initio 3D numerical simulations, we investigate in detail the interaction of a hydrogen atom with intense Gaussian and Laguerre-Gaussian light pulses. We analyze the dependence of the angular momentum exchange with the polarization, the orbital angular momentum, and the carrier-envelope phase of light, as well as with the relative position between the atom and the light vortex. In addition, a quantum-trajectory approach based on the de Broglie-Bohm formulation of quantum mechanics is used to gain physical insight into the absorption of angular momentum by the hydrogen atom.

quant-ph↗

arXiv2008

Measuring the Complete Transverse Spatial Mode Spectrum of a Wave Field

We put forward a method that allows the experimental determination of the entire spatial mode spectrum of any arbitrary monochromatic wave field in a plane normal to its propagation direction. For coherent optical fields, our spatial spectrum analyzer can be implemented with a small number of benchmark refractive elements embedded in a single Mach-Zehnder interferometer. We detail an efficient setup for measuring in the Hermite-Gaussian mode basis. Our scheme should also be feasible in the context of atom optics for analyzing the spatial profiles of macroscopic matter waves.

quant-ph↗

arXiv2008

Manipulation of single-photon states encoded in transverse spatial modes: possible and impossible tasks

Controlled generation and manipulation of photon states encoded in their spatial degrees of freedom is a crucial ingredient in many quantum information tasks exploiting higher-than-two dimensional encoding. Here, we prove the impossibility to arbitrarily modify $d$-level state superpositions (qu$d$its) for $d>2$, encoded in the transverse modes of light, with optical components associated to the group of symplectic transforms (Gaussian operations). Surprisingly, we also provide an explicit construction of how non-Gaussian operations acting on mode subspaces do enable to overcome the limit $d=2$. In addition, this set of operations realizes the full SU(3) algebra.

quant-ph↗

arXiv2007

Spin-induced angular momentum switching

When light is transmitted through optically inhomogeneous and anisotropic media the spatial distribution of light can be modified according to its input polarization state. A complete analysis of this process, based on the paraxial approximation, is presented, and we show how it can be exploited to produce a spin-controlled-change in the orbital angular momentum of light beams propagating in patterned space-variant-optical-axis phase plates. We also unveil a new effect. The development of a strong modulation in the angular momentum change upon variation of the optical path through the phase plates.

quant-ph↗