arXiv subjects

Humberto Michinel

Publications and source records attributed to Humberto Michinel.

At least 37 records · Page 2Linked to original sources

arXiv2009

Dripping, pressure and surface tension of self-trapped laser beams

We show that a laser beam which propagates through an optical medium with Kerr (focusing) and higher order (defocusing) nonlinearities displays pressure and surface-tension properties yielding capillarity and dripping effects totally analogous to usual liquid droplets. The system is reinterpreted in terms of a thermodynamic grand potential, allowing for the computation of the pressure and surface tension beyond the usual hydrodynamical approach based on Madelung transformation and the analogy with the Euler equation. We then show both analytically and numerically that the stationary soliton states of such a light system satisfy the Young-Laplace equation, and that the dynamical evolution through a capillary is described by the same law that governs the growth of droplets in an ordinary liquid system.

nlin.PS↗

arXiv2008

Nonlinear Propagation of Crossing Electromagnetic Waves in Vacuum due to Photon-Photon Scattering

We review the theory for photon-photon scattering in vacuum, and some of the proposals for its experimental search, including the results of our recent works on the subject. We then describe a very simple and sensitive proposal of an experiment and discuss how it can be used at the present (HERCULES) and the future (ELI) ultrahigh power laser facilities either to find the first evidence of photon-photon scattering in vacuum, or to significantly improve the current experimental limits.

physics.optics↗

arXiv2008

Supersolitons: Solitonic excitations in atomic soliton chains

We show that, by appropriately tuning physically relevant interactions in two-component nonlinear Schrodinger equations, it is possible to achieve a regime with particle-like solitonic collisions. This allows us to construct an analogue of the Newton's cradle and also to create localized collective excitations in solitary-wave chains which are quasi-integrable solitons, i.e. supersolitons. We give a physical explanation of the phenomenon, support it with a perturbative analysis, and confirm our predictions by direct simulations.

nlin.PS↗

arXiv2008

Non-quantum liquefaction of coherent gases

We show that a gas-to-liquid phase transition at zero temperature may occur in a coherent gas of bosons in the presence of competing nonlinear effects. This situation can take place both in atomic systems like Bose-Einstein Condensates in alkalii gases with two and three-body interactions of opposite signs, as well as in laser beams which propagate through optical media with Kerr (focusing) and higher order (defocusing) nonlinear responses. The liquefaction process takes place in absence of any quantum effect and can be formulated in the frame of a mean field theory, in terms of the minimization of a thermodynamic potential. We also show numerically that the effect of linear gain and three-body recombination also provides a rich dynamics with the emergence of self-organization behaviour.

nlin.PS↗

arXiv2008

Detecting photon-photon scattering in vacuum at exawatt lasers

In a recent paper, we have shown that the QED nonlinear corrections imply a phase correction to the linear evolution of crossing electromagnetic waves in vacuum. Here, we provide a more complete analysis, including a full numerical solution of the QED nonlinear wave equations for short-distance propagation in a symmetric configuration. The excellent agreement of such a solution with the result that we obtain using our perturbatively-motivated Variational Approach is then used to justify an analytical approximation that can be applied in a more general case. This allows us to find the most promising configuration for the search of photon-photon scattering in optics experiments. In particular, we show that our previous requirement of phase coherence between the two crossing beams can be released. We then propose a very simple experiment that can be performed at future exawatt laser facilities, such as ELI, by bombarding a low power laser beam with the exawatt bump.

physics.optics↗

arXiv2007

Nonlinear phase shift from photon-photon scattering in vacuum

We show that QED nonlinear effects imply a phase correction to the linear evolution of electromagnetic waves in vacuum. We provide explicit solutions of the modified Maxwell's equations for the propagation of a superposition of two plane waves, and calculate analytically and numerically the corresponding phase shift. This provides a new framework for the search of all-optical signatures of photon-photon scattering in vacuum. In particular, we propose an experiment for measuring the phase shift in projected high-power laser facilities.

physics.optics↗

arXiv2007

Laser tweezers for atomic solitons

We describe a controllable and precise laser tweezers for Bose-Einstein condensates of ultracold atomic gases. In our configuration, a laser beam is used to locally modify the sign of the scattering length in the vicinity of a trapped BEC. The induced attractive interactions between atoms allow to extract and transport a controllable number of atoms. We analyze, through numerical simulations, the number of emitted atoms as a function of the width and intensity of the outcoupling beam. We also study different configurations of our system, as the use of moving beams. The main advantage of using the control laser beam to modify the nonlinear interactions in comparison to the usual way of inducing optical forces, i.e. through linear trapping potentials, is to improve the controllability of the outcoupled solitary wave-packet, which opens new possibilities for engineering macroscopic quantum states.

cond-mat.other↗

arXiv2006

A ring accelerator for matter-wave solitons

We describe a new technique to accelerate and control a confined cloud of ultracold neutral atoms. In our configuration, a Bose-Einstein Condensate trapped in a ring is accelerated by using an amplitude-modulated optical potential. The spreading of the atomic cloud is avoided by an adequate tuning of the scattering length. We also discuss other variations that offer new possibilities of robust control of atomic solitons. Our numerical results show that this cold matter accelerator is easily accessible in the frame of current experiments.

cond-mat.soft↗

arXiv2006

Lattice hyper-solitons in photorrefractive materials

We show a novel kind of nonlinear waves in two-dimensional photonic lattices. This waves take the form of light clusters that may fill an arbitrary number of lattice sites. We have demonstrated by numerical simulations that stable propagation can be achieved under adequate conditions and we have described the unstable patterns developed otherwise. Our results show that these new kind of nonlinear waves can be easily found in current experiments.

nlin.PS↗

arXiv2006

Analysis of an atom laser based on the spatial control of the scattering length

In this paper we analyze atom lasers based on the spatial modulation of the scattering length of a Bose-Einstein Condensate. We demonstrate, through numerical simulations and approximate analytical methods, the controllable emission of matter-wave bursts and study the dependence of the process on the spatial dependence of the scattering length along the axis of emission. We also study the role of an additional modulation of the scattering length in time.

cond-mat.other↗

arXiv2005

Turning light into a liquid via atomic coherence

We study a four level atomic system with electromagnetically induced transparency with giant $χ^{(3)}$ and $χ^{(5)}$ susceptibilities of opposite signs. This system would allow to obtain multidimensional solitons and light condensates with surface tension properties analogous to those of usual liquids.

nlin.PS↗

arXiv2005

Controllable soliton emission from a Bose-Einstein condensate

We demonstrate, through numerical simulations, the controllable emission of matter-wave bursts from a Bose-Einstein Condensate in a shallow optical dipole trap. The process is triggered by spatial variations of the scattering length along the trapping axis. In our approach, the outcoupling mechanism are atom-atom interactions and thus, the trap remains unaltered. Once emitted, the matter wave forms a robust soliton. We calculate analytically the parameters for the experimental implementation of this atomic soliton machine gun.

cond-mat.other↗

arXiv2005

Spatial vector solitons in nonlinear photonic crystal fibers

We study spatial vector solitons in a photonic crystal fiber (PCF) made of a material with the focusing Kerr nonlinearity. We show that such two-component localized nonlinear waves consist of two mutually trapped components confined by the PCF linear and the self-induced nonlinear refractive indices, and they bifurcate from the corresponding scalar solitons. We demonstrate that, in a sharp contrast with an entirely homogeneous nonlinear Kerr medium where both scalar and vector spatial solitons are unstable and may collapse, the periodic structure of PCF can stabilize the otherwise unstable two-dimensional spatial optical solitons. We apply the matrix criterion for stability of these two-parameter solitons, and verify it by direct numerical simulations.

nlin.PS↗

arXiv2004

n-body dynamics of stabilized vector solitons

In this work we study the interactions between stabilized Townes solitons. By means of effective Lagrangian methods, we have found that the interactions between these solitons are governed by central forces, in a first approximation. In our numerical simulations we describe different types of orbits, deflections, trapping and soliton splitting. Splitting phenomena are also described by finite dimensional reduced models. All these effects could be used for potential applications of stabilized solitons.

nlin.PS↗

arXiv2004

Controllable matter-wave switchers with vector Bose-Einstein solitons

We show the possibility of producing matter-wave switching devices by using Manakov interactions between matter wave solitons in two-species Bose-Einstein Condensates (BEC). Our results establish the experimental parameters for three interaction regimes in two-species BECs: symmetric and asymmetric splitting, down-switching and up-switching. We have studied the dependence upon the initial conditions and the kind of interaction between the two components of the BECs.

cond-mat.soft↗

arXiv2004

Stable propagation of pulsed beams in Kerr focusing media with modulated dispersion

We propose the modulation of dispersion to prevent collapse of planar pulsed beams which propagate in Kerr-type self-focusing optical media. As a result, we find a new type of two-dimensional spatio-temporal solitons stabilized by dispersion management. We have studied the existence and properties of these solitary waves both analytically and numerically. We show that the adequate choice of the modulation parameters optimizes the stabilization of the pulse.

nlin.PS↗

arXiv2004

Square vortex solitons with a large angular momentum

We show the existence of square shaped optical vortices with a large value of the angular momentum hosted in finite size laser beams which propagate in nonlinear media with a cubic-quintic nonlinearity. The light profiles take the form of rings with sharp boundaries and variable sizes depending on the power carried. Our stability analysis shows that these light distributions remain stable when propagate, probably for unlimited values of the angular momentum, provided the hosting beam is wide enough. This happens if the peak amplitude approaches a critical value which only depends on the nonlinear refractive index of the material. A variational approach allows us to calculate the main parameters involved. Our results add extra support to the concept of surface tension of light beams that can be considered as a trace of the existence of a liquid of light.

nlin.PS↗

arXiv2004

Stabilized vortex solitons in layered Kerr media

In this letter we demonstrate the possibility of stabilizing beams with angular momentum propagating in Kerr media. Large propagation distances without filamentation can be achieved in layered media with alternating focusing and defocusing nonlinearities. Stronger stabilization can be obtained with the addition of an incoherent beam.

nlin.PS↗