Coherent light sources and optical techniques for Thomson scattering and Laser-Plasma experiments

Recent progress in accelerators and lasers technology opens new perspectives in terms of particle-photon colliders luminosity: low cross section processes can be therefore utilized to create specific radiation sources. Indeed, exploiting the inverse Compton scattering or Thomson back-scattering process, the interaction between relativistic electron beams (γ >> 1) and near-infrared laser pulses (λ ≈ 1μm) yields electromagnetic waves in the X-ray and γ-ray range. The energy, the flux and the spectrum of such kind of generated radiation are suitable for many purposes, e.g. dynamical studies and imaging of solid, molecular and biological systems. Nevertheless, the big development in the high power laser field, begun in the ’80s thanks to the chirped pulse amplification (CPA) scheme [66], has provided systems to be employed in the study of the laser wakefield acceleration (LWFA). As stated by Tajima and Dawson in 1979, an intense laser pulse, propagating through a plasma, can stimulate plasma waves able to accelerate electrons with accelerating gradients greater than 100 GV/m, i.e. some orders of magnitude more than the conventional RF-based LINAC. Moreover, with TW-class laser systems and intensity more than 10^18 W/cm^2, the relativistic regime occurs and electrons can be self-injected into the plasma accelerating structure. This opens the possibility to build much more compact particle accelerators, even though the beam quality, in terms of emittance and energy spread, is not yet comparable to the standard linear accelerator. In this work, the activity related to Thomson back-scattering and laser-plasma interaction pursued at SPARC_LAB Facility in Frascati (Italy) will be presented. SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) is a multi-disciplinary facility aiming to test new radiation source (THz, XUV, X-Ray) exploiting different phenomena such Free Electron Laser (FEL), Coherent Transition Radiation (CTR) and Thomson back-scattering, thank to the high brightness electron beam that it can provide. The peculiarity of SPARC_LAB is the presence of 300 TW FLAME laser together with the high brightness LINAC. This kind of laser represents a powerful tool to study Thomson back-scattering, when combining it with the linear accelerator, as well as the interaction with the matter, mainly to perform experiments related to LWFA, both in self-injection and external-injection regime. Furthermore, a development of a new diagnostics tool able to measure electron beam emittance in a single shot way will be presented. This novel technique seems to be very useful for beam from plasma accelerators, since they suffer shot-by-shot instabilities. Therefore, a statistical measurement would me meaningless while a single shot diagnostics can provide a more useful description of electron beam parameters. Simulations and some preliminary results will be provided. In addiction, also a research activity on interaction with solid target has been conducted in order to study the possibility to optimize the ion acceleration without increasing the laser energy but opportunely shaping the target itself

Device-independent certification of high-dimensional quantum systems

An important problem in quantum information processing is the certification of the dimension of quantum systems without making assumptions about the devices used to prepare and measure them, that is, in a device-independent manner. A crucial question is whether such certification is experimentally feasible for high-dimensional quantum systems. Here we experimentally witness in a device-independent manner the generation of six-dimensional quantum systems encoded in the orbital angular momentum of single photons and show that the same method can be scaled, at least, up to dimension 13.Comment: REVTeX4, 5 pages, 2 figure

Resilience of hybrid optical angular momentum qubits to turbulence

Recent schemes to encode quantum information into the total angular momentum of light, defining rotation-invariant hybrid qubits composed of the polarization and orbital angular momentum degrees of freedom, present interesting applications for quantum information technology. However, there remains the question as to how detrimental effects such as random spatial perturbations affect these encodings. Here, we demonstrate that alignment-free quantum communication through a turbulent channel based on hybrid qubits can be achieved with unit transmission fidelity. In our experiment, alignment-free qubits are produced with q-plates and sent through a homemade turbulence chamber. The decoding procedure, also realized with q-plates, relies on both degrees of freedom and renders an intrinsic error-filtering mechanism that maps errors into losses

Simultaneous observation of ultrafast electron and proton beams in TNSA

The interaction of ultra-intense high-power lasers with solid-state targets has been largely studied for the past 20 years as a future compact proton and ion source. Indeed, the huge potential established on the target surface by the escaping electrons provides accelerating gradients of TV/m. This process, called target normal sheath acceleration, involves a large number of phenomena and is very difficult to study because of the picosecond scale dynamics. At the SPARC_LAB Test Facility, the high-power laser FLAME is employed in experiments with solid targets, aiming to study possible correlations between ballistic fast electrons and accelerated protons. In detail, we have installed in the interaction chamber two different diagnostics, each one devoted to characterizing one beam. The first relies on electro-optic sampling, and it has been adopted to completely characterize the ultrafast electron components. On the other hand, a time-of-flight detector, based on chemical-vapour-deposited diamond, has allowed us to retrieve the proton energy spectrum. In this work, we report preliminary studies about simultaneous temporal resolved measurements of both the first forerunner escaping electrons and the accelerated protons for different laser parameters

Ray optics hamiltonian approach to relativistic self focusing of ultraintense lasers in underdense plasmas

The relativistic self focusing of an ultraintense laser propagating through an underdense plasma is analyzed from a geometrical optics point of view, exploiting the classical hamiltonian formalism. The distribution of the laser intensity along the self-generated plasma channel is studied and compared to measurements

Ray optics hamiltonian approach to relativistic self focusing of ultraintense lasers in underdense plasmas

The relativistic self focusing of an ultraintense laser propagating through an underdense plasma is analyzed from a geometrical optics point of view, exploiting the classical hamiltonian formalism. The distribution of the laser intensity along the self-generated plasma channel is studied and compared to measurements

An ultra short pulse reconstruction software applied to the GEMINI high power laser system

The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class