Események

Since the invention of laser wakefields, generated by high intensity, femtosecond pulses in gaseous targets, the electron acceleration in dilute plasmas has been investigated both theoretically and experimentally. This scheme looks extremely promising to partially replace the conventional accelerators and to generate high quality relativistic electron bunches reaching several GeV maximum energies. However, in the case of ultrashort pulses new physical effects emerge, which are not yet fully understood, or not explored in the literature. Since the propagation of ultrashort laser pulses in plasma is highly nonlinear, it is necessary to model the interaction by means of numerical simulations. With the help of such (particle-in-cell) simulations I studied the electron acceleration process driven by very short (few-cycle) pulses and identified several negative effects which are not so important (or not present) in the case of longer pulses. Based on the knowledge acquired in the last two years I designed a three-component target, which is suitable for very efficient electron acceleration and allows for high energy gain within 2-millimeter distance. In my talk I will present the theoretical description of the short-pulse propagation in the proposed millimeter-long, three-stage target and I will show that, theoretically, GeV-class electron bunches can be accelerated by a half-Joule laser pulse in this new scheme.

In the second part of my talk, I will briefly discuss the possibility of proton (or deuteron) acceleration from high density gas jets using ~ 100 mJ laser pulses, which is highly relevant to the SYLOS-2 laser installed at ELI ALPS. I will present a realistic 3D simulation which indicates that 1 MeV mono-energetic proton bunch can be generated by such ultra-short laser pulses at ~kHz repetition rate.

Recent progresses in development of broad-band laser systems lead to the stable production of nearly single-cycle pulses at high repetition rates which then require tight focusing optics in order to reach highly relativistic intensities, needed for laser-plasma experiments. Most of the laser-driven particle acceleration schemes rely on particle-in-cell simulations where the laser pulses are usually initialized with Gaussian transverse profiles, employing the paraxial approximation at the beginning of the interaction. For tightly focused ultrashort pulses, however, a more accurate description is needed, otherwise the arising numerical artifacts may detrimentally affect the simulation outcome.

We present a general analytical-numerical framework going beyond the paraxial description for the laser electric and magnetic fields valid up to the near single-cycle pulse durations and focused beam spot sizes. We introduce corrections regarding spatial-temporal coupling, and corrections for the vector components of the electric- and magnetic-fields that could give precise initial fields for existing Maxwell-solvers ready to be used in particle-in-cell simulations. We combine this framework with beams based on the multimodal decomposition on the real Laguerre-Gaussian mode basis, to model pulses that have - more realistic- high order super-Gaussian profiles away from the focus in the same way.

Light induced chemical processes are mediated by electronic interactions, which happens from atto-femto-pico second timescales, and are sensitive to the molecular structure. With advances in femto-second laser technology it has become possible to reach electric field values similar to the atomic/molecular binding potential. When an atom/molecule is exposed to such intense electromagnetic fields the potential barrier of the atom/molecule is considerably modified by the electromagnetic field. This modification is a dynamical process (see Fig 1.), occurring as the electromagnetic field oscillates, i.e. on the attosecond timescale (it takes only ~667 as for a visible electric field to go from its peak to zero). At the maximum of the laser field (Fig 1. a), the molecular potential barrier is lowered significantly and the electrons can tunnel out of this reduced barrier into the continuum (Fig 1. a 1). These tunnelled electrons are then driven by the oscillating laser field and can follow different trajectories (Fig 1. a 2). Some of them can be driven back to the ionic core, leading to a variety of processes: re-scattering, or recombination back to the ion emitting an XUV photon, or even diffraction from the molecular potential itself (Fig 1. b). These phenomena, referred to as “self-imaging”, enable measuring structural and dynamics information with unprecedented resolutions – Angströms and attoseconds. However, as the complexity of the target increases, deciphering the information becomes more difficult, such that the majority of self-imaging measurements have up to now been restricted to small systems (diatomics, triatomics).

In this work, we investigate the sensitivity of self-imaging to molecular chirality. We measure the 3D photoelectron angular distributions resulting from the photoionization of fenchone and alpha-pinene molecules by a strong infrared laser field. When the field is circularly polarized, the electron distribution is asymmetric relative to the laser propagation axis: more electrons are ejected forward or backward, depending on the handedness of the molecule and the incident light. This chiroptical process, called Photo-Electron Circular Dichroism, is a pure electric dipole effect, leading to asymmetries in the few % range. When we switch the polarization state to elliptical, we observe the emergence of much higher energy electrons, which have been driven back towards their parent ion by the laser field before diffracting on the potential. We observe a strong forward-backward asymmetry in these diffracted electrons, and we show that this chiral laser-induced electron diffraction is very sensitive to the molecular structure. Last, we switch to linearly polarized laser pulses, and measure a chirosensitive rotation of the photoelectron angular distribution around the light propagation direction. This effect is interpreted as the result of the action of the laser magnetic field on the electron trajectories.

Figure 1. Dynamical processes involved in strong-field ionization: a) At peak electric field the electrons tunnels out of the modified potential barrier, b) when the electric field reverses sign in the next half cycle these electrons maybe driven back to ionic core leading to re-scattering, recombination or diffraction.

We discuss the exact relativistic description of both the classical and the quantum mechanical motion of charged particles interacting with a laser field of arbitrary intensity. This subject gives us also a good opportunity to celebrate the centenary of Compton’s discovery [1], which is an important ingredient of quantum electrodynamics (QED). First, in a brief historical overview we shall highlight the wave-particle duality and simultaneity in Compton scattering [2], [3].

The exact solutions of the Lorentz and Dirac equations of a charged particle in a plane electromagnetic wave in vacuum are represented by the well-known figure-8 motion and the Volkov states, respectively. These solutions have been extensively used in describing high-harmonic emission and attosecond pulse generation in the Compton or Thomson scattering processes [4]. They also have a role in the physics of free electron lasers [5]. Here we point out the surprising mathematical connection between the relativistic figure-8 motion in a monochromatic radiation and the classical Kepler-Coulomb trajectories in a central field [6].

By going beyond the external field approximation, the Dirac (Klein-Gordon or Schrödinger) equation of the joint system of a charged particle interacting with quantized radiation modes in vacuum can also be solved exactly in various cases [7], [8]. The photon part of the single-mode stationary states are squeezed (coherent) number states. The photon statistics has been determined quite recently in terms of Gegenbauer polynomials [9], and this is now used for a refined analysis of high-harmonic generation in a quantized radiation field, which was first studied long ago [7].

Finally we discuss the interaction of a charged Dirac particle with two co-propagating circularly polarized quantized modes. On the basis of the recently found exact solutions, we shall see that entangled photon pairs naturally appear in this system, like in the quantum optical non-degenerate parametric down-conversion process. In a special case the probability amplitudes of the distribution of these photon pairs reduce to Zernike functions, which are well-kown in the theory of aberration in classical optical imaging. Accordingly, it is justified to introduce the concepts of aberration and Zernike moments on quantum phase space, which may give a new aspect in the theoretical study of high-order QED and parametric processes in laser-matter interactions.

References.

[1] Compton A H 1922 The spectrum of secondary X-rays. Phys. Rev. 19, 267-268 (1922).

[2] Compton A H and Simon A W 1925 Directed quanta of scattered X-rays. Phys. Rev. 26, 289-299 (1925).

[3] Bay Z, Henri V P and Mc Lernon F 1955 Simultaneity in the Compton effect. Phys. Rev. 97, 1710-1712 (1955).

[4] Hack Sz, Varró S and Czirják A 2018 Carrier-envelope phase controlled isolated attosecond pulses in the nm wavelength range, based on coherent nonlinear Thomson back-scattering. New Journal of Physics 20, 073043 (2018).

[5] Varró S 2012 (Ed.) Free Electron Lasers.  (Rijeka, InTech, 2012).

[6] Varró S 2010 Intensity effects and absolute phase effects in nonlinear laser-matter interactions. In Laser Pulse Phenomena and Applications. (Duarte F J (Ed.); Rijeka, InTech, 2010). Chapter 12.

[7] Bergou J and Varró 1981 Nonlinear scattering processes in the presence of a quantised radiation field: II. Relativistic treatment. Journal of Physics A: Math. Gen. 14, 2281-2303 (1981).

[8] Varró S 2021 Quantum optical aspects of high-harmonic generation. Photonics 8, 269 (2021).         

[9] Varró S 2022 Coherent and incoherent superposition of transition matrix elements of the squeezing operator. New Journal of Physics 24, 053035 (2022).

This seminar will provide a general overview of the U.S. federal science funding landscape with a focus on physical sciences.  The U.S. federal science funding is allocated by the U.S. Congress via several federal agencies, including the National Science Foundation, the Department of Energy, the National Institute of Health, the National Aeronautics and Space Administration, and many others.  It is a uniquely complex system where federal agencies responsible for support of fundamental research interact with the applied mission-focused agencies that pursue specific societal, technological, and/or national security goals.  I will provide an in-depth look into the functioning of my own agency, the National Science Foundation, and will use the field of plasma science and engineering as a prime example of a research field where inter-agency and international cooperation play an essential role in the science funding landscape.

Program:

9:30 – 9:40         Gábor Szabó (ELI ALPS) - Welcome notes

9:40 – 10:30       Pulickel M. Ajayan (Rice University) - Materials Design through NanoEngineering

The last two decades in engineering sciences have been dominated by spectacular discoveries in nanotechnology. This talk will focus on some of these developments and in particular the challenges and opportunities in designing and synthesizing functional nanoengineered materials. The talk will discuss several classes of materials, for example, carbon-based nanostructures and two-dimensional structures, and the impact of bottom-up engineering on the design of material systems relevant to many areas of applications including energy, structural, chemical, and electronics. Several aspects that include synthesis, processing and manufacturing of materials will be broadly discussed to convey the goals of achieving functional nanoengineered materials.

10:30 – 11:20    Róbert Vajtai (Rice University) - sp2 to sp3 Materials for Ultrawide- Bandgap Electronics

State-of-the-art electronics is one of the driving forces in materials development. While the development of the most widely appreciated new materials target mini(nano)aturization and low energy dissipation, some applications request development in the opposite direction: developing devices for high-power and high-frequency electronics. In this talk, I summarize the properties of the most important UWBG materials and talk about our work on the growth and characterization of diamond and boron nitride for applications in advanced electronics.

11:20 – 12:10    Levente Tapasztó (Centre for Energy Research) - Engineering the Properties of 2D TMC Crystals by Structural Modifications down to Atomic Level

Transition metal chalcogenides (TMCs) are among the most widely studied two-dimensional (2D) materials, second only to graphene. In this talk, I will discuss our various contributions to the field of 2D TMC materials: their large-area exfoliation, revealing their intrinsic defect structure, and how it affects the electronic structure, strain engineering of their band gap, as well as their atomic-level structural modification for engineering their properties.

12:10 – 13:00    Katalin Varjú (ELI ALPS) - Commissioning Progress and User Access at the ELI ALPS Research Institute

The primary mission of the ELI ALPS research facility in Szeged, Hungary is to provide laser and secondary light and particle sources in the form of ultrashort bursts with high repetition rates. Energetic coherent light pulses of few optical cycles are available from the terahertz (1012 Hz) to the X-ray (1018 — 1019 Hz) frequency range. ELI ALPS will be dedicated to study extremely fast dynamics by taking snapshots in the attosecond scale of the electron dynamics in atoms, molecules, plasmas and solids. The parallel existence of these secondary sources and state of the art lasers including PW-class lasers within the same facility, offers unique time-resolved investigation possibilities for both nonrelativistic and relativistic interaction of light with all the four phases of matter. ELI ALPS will also pursue research with ultrahigh intensity lasers.

The constructed buildings house the laser equipment, secondary sources, target areas, laser preparation and other special laboratories, including 4.000m2 of clean rooms. It also provides sufficient administration space for approximately 250 researchers and support staff. There are seminar, meeting and conference rooms. There are also electrical, mechanical and optical workshops. These state-of-the-art facilities require specialised engineering design and cutting-edge implementation of the latest technology for vibration levels, thermal stability, relative humidity, clean room facilities and radiation protection conditions. The ELI-ALPS is approaching the end of the construction phase for the main priority being the installation and commissioning of the remaining research technology.

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In the first part of the talk we attempt to give a brief exposition of the scientific background of the subject we are discussing. The following points will be highlighted: The coherent and squeezed states of a quantum-mechanical harmonic oscillator (which may also represent a photon mode of the electromagnetic radiation) have already been  known immediately after the invention of wave mechanics. Not much later, in 1935, Schrödinger introduced the concept of entanglement (“Verschränkung”), when the quanta are distributed coherently among several degrees of freedom. His analysis was motivated by the critics due to Einstein, Podolsky and Rosen (EPR, 1935), of the quantum description, in general. The experimental investigations of such fundamental questions became possible after the invention of the laser. From the sixthies of the last century the quantum states of light have played an important role in the theory and practice of lasers and parametric processes in quantum optics and quantum imaging [1], [2], [3]. The study and application of entanglement have become one of the main ingredients of quantum information science [4]. The non-classical states also naturally appear in the non-perturbative description of the minimal coupling interaction of radiation fields with charges, e.g. in the non-linear Compton process or in high-order harmonic generation [5], [6], [7], so they have a role in attosecond physics, too. 

Recently we have derived the probability amplitudes of general squeezing transitions, in terms of Gegenbauer polynomials [8]. On the basis of this result we have also determined the photon statistics of thermal noise (black-body radiation) amplification in a degenerate parametric amplifier. In the meantime we have applied an analogous mathematical procedure for the non-degenerate process producing EPR-type entangled photon pairs. In the second half of the talk we shall discuss the results of the latter study. The photon statistics of the entangled photon pairs have been calculated, in a close connection with the quantum phase formalism, which we have already introduced earlier [9]. It will be shown that in a special case, the derived probability amplitudes reduce to the Zernike functions (polynomials), well-kown in the classical theory of aberration in optical imaging. The quantum Zernike polynomials depend on the phase-space variables, and they form a complete set of orthogonal aberration functions. Thanks to these results, it is possible to quantitatively assess the parametric photon sources, for example, in terms of the corresponding Zernike moments. 

References.

[1] Lugiato L A, Gatti A and Brambilla E, Quantum imaging. J. Opt. B: Quantum Semiclass. Opt. 4 (2002) S176–S183.

[2] Dodonov V V, Nonclassical states in quantum optics: a squeezed review of the first 75 years. J. Opt. B: Quantum Semiclass. Opt. 4,R1–R33 (2002). 

[3] Andersen U L et al, 30 years of squeezed light generation. Phys. Scr. 91, 053001 (2016). 

[4] > The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2022 to Alain Aspect, John F. Clauser and Anton Zeilinger; “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”. https://www.nobelprize.org/uploads/2022/10/press-physicsprize2022-2.pdf  <

[5] Varró S : Entangled photon-electron states and the number-phase minimum uncertainty states of the photon field. New Journal of Physics 10, 053028 (2008)

[6] Varró S : Entangled states and entropy remnants of a photon-electron system. Physica Scripta T140, 014038 (2010).

[7] Varró S, Quantum optical aspects of high-harmonic generation. Photonics 2021, 8, 269 (2021).  

[8] Varró S, Coherent and incoherent superposition of transition matrix elements of the squeezing operator. New Journal of Physics 24, 053035 (2022). 

[9] Varró S : Regular phase operator and SU(1,1) coherent states of the harmonic oscillator. Physica Scripta 90 (7) 074053 (2015).

Directly observing electron dynamics at surfaces is required to understand and control the material properties that determine efficiency of many applications including efficient energy conversion as well as ultrafast information processing.  Toward this goal, we have developed extreme ultraviolet reflection-absorption (XUV-RA) spectroscopy as a surface-specific analog of XUV transient absorption.  This method combines the benefits of traditional X-ray absorption spectroscopy, such as element, oxidation, and spin state resolution, with surface sensitivity and ultrafast time resolution.  Using this technique, we investigate charge and spin dynamics in materials with applications ranging from photocatalysis to optical control of magnetic switching.  In one example, we describe a systematic comparison of surface and bulk electron polaron formation in hematite showing that surface self-trapping dynamics differ significantly from bulk and that these dynamics can be systematically tuned by surface molecular functionalization offering the possibility for design of photocatalytic interfaces with enhanced carrier transport based on earth abundant materials.  In a second example, we highlight evolving applications of XUV-RA spectroscopy to study spin dynamics at surfaces.  Applications include understanding ultrafast spin crossover in magnetic semiconductors as well as control of spin polarized electron dynamics at chiral photochemical interfaces.  Last, I will describe capabilities that will soon become available at the NSF National eXtreme Ultrafast Science Facility (NeXUS) that is currently under development at Ohio State University.

Spectroscopy provides our main window on the Universe about us. The detection of many exoplanets orbiting nearby stars has led to the desire to characterize these planets by looking at their spectra. The ERC-funded ExoMol project which I lead provides the  spectroscopic data needed for this activity; given that many of the observed planets are hot these datasets are huge. The seminar will discuss how we compute spectroscopic line lists and the extension of the methodology to photodissociation, and the use of these data in both astrophysical and terrestrial applications. Procedures to compute photodissociation spectra will also be outlined.

In the framework of the established series of Users’ Workshops the Extreme Light Infrastructure – Attosecond Light Pulse Source (ELI ALPS)  is organizing its ninth User Workshop on November 3 and 4, 2022. This year the Users’ Workshop is organized as an ELI ERIC (https://eli-laser.eu/) joint event.

In the framework of the established series of Users’ Workshops the Extreme Light Infrastructure – Attosecond Light Pulse Source (ELI ALPS)  is organizing its ninth User Workshop on November 3 and 4, 2022. This year the Users’ Workshop is organized as an ELI ERIC (https://eli-laser.eu/) joint event.

I start with brief introduction of the present status of Institute Laser Engineering (ILE) of Osaka University. Then, the topics on Laser Driven Ion Acceleration (LDIA) and Laser Driven Neutron Source (LDNS) researches at ILE are presented. Since early 1990’s, various schemes of LDIA are investigated as one of the applications of the intense short-pulse-laser interaction with plasmas [1]. The LDIA has been applied for radiography, medical application, neutron source and so on. In this seminar, I overview the researches at ILE Osaka Univ. on LDIA, laser driven neutron source (LDNS) [2]and its application to nuclear resonance absorption (NRA) [3] .

The LDNS is unique because the number of neutrons per micro pulse is very large and the source size and the pulse width are small. Therefore, the extensive research and development of LDNS are going on in the world. A scheme of LDNS (Pitcher- catcher) by the LDIA is described, which is the Pitcher-Catcher Scheme (PCS). The characteristics of the LDNS by PCS are compared with those of the accelerator driven neutron source (ADNS). Then, I explain a unique application of LDNS such as the nuclear resonance absorption (NRA) imaging. Namely, by the LDNS, the NRA imaging is possible with a relatively short beam line in comparison with that of the ADNS, since the neutron pulse width and the source size of LDNS are small. The future prospect of the R&D of the NRA imaging with LDNS [4] is also discussed.

[1] A. Macchi, P.59-P.92, Chap.5 Laser Driven Ion Acceleration, “Application of Laser-Driven Particle Acceleration”, Edited by P.R. Bolton, K. Parodi, and J. Schreiber, CRC press, Taylor &  Francis Group, 2018, (M. Borghesi will present this topic on LDIA in this seminar.)

[2] Lancaster, K.L., Karsch, S., Habara, H., et al., Characterization of 7Li(p,n)7Be neutron yields from laser produced ion beams for fast neutron radiography, Physics of Plasmas, 11.3404(2004)

[3] S. Kar, A. Green, H. Ahmed, A. Alejo, A.P.L. Robinson, M. Cerchez, R. Clarke, D. Doria, S. Dorkings, J. Fernandez, S.R. Mirfayzi1, P. McKenna5, K. Naughton1, D. Neely2, P. Norreys2,6, C. Peth3, H. Powell, J. A. Ruiz, J. Swain, O. Willi and M. Borghesi, “Beamed neutron emission driven by laser accelerated light ions” New J. Phys. 18, 053002 (2016).

[4] A.Yogo, et al., “Laser-driven neutron generation realizing single-shot resonance Spectroscopy”, to be published in PRX, 2022.

In our earlier studies [1-3] we have shown that the Planck-Bose distribution of black-body radiation can be derived from the exponential  distribution, by splitting the continuous random energy into its integer and fractional part [3]. The binary digits (0 and 1) of the fractional part (which may also be considered as a sort of rounding-off error in energy measurements) inherit the randomness, and they are independent random variables [4]. According to our recent investigations, the variance of the  fractional part is the sum of particle-like and a wave-like fluctuations [1-2]. In the first part of the talk we discuss some features of the associated ‘particles’ which may be called ‘dark quanta’ or ‘grey photons’, since at large temperatures their energy is 2kT, where k is the Boltzmann constant and T is the absolute temperature. 

In the second part of the talk we shall discuss the statistics of a two-level system being in thermal equilibrium with the black-body radiation. By associating the numbers 0 and 1 to the ground state and to the excited state, respectively, the outcomes of a series of measurements of the population can be mapped to the continuum of numbers (like x = 0.10010110010...) of the unit interval. The relative frequencies of digits 0 and 1 tend to the corresponding probabilities, namely to 1 – b and b, respectively, where b is the Boltzmann factor of the upper state.  If b = 1/2, then the points corresponding to the realizations in the measurements visit the whole unit interval, except for a set of (Lebesgue) measure zero. In order to compare the sizes of sets of measure zero, the use of Hausdorff fractional dimensions has first been worked out by Besicovitch [5], and generalized later by others. By applying the mathematical results in [5], it turns out that the entropy of the two-level system is k(log2) times the Hausdorff fractional dimension d of the set of average populations in the unit interval. For instance,  in cases of b=1/2 and b=1/5 we have d=1 and d=0.721928, respectively. The Planck entropy of the corresponding spectral component of the black-body radiation can also be expressed by the Hausdorff dimension [6]. Our results contribute to the mathematics of digital processing measurement results, and may also be useful in describing some physical systems generating random numbers. 

[1] Varró S, Einstein's fluctuation formula. A historical overview. Fluctuation and Noise Letters, 6, R11-R46 (2006). arXiv: quant-ph/0611023 . 

[2] Varró S, A study on black-body radiation: classical and binary photons. Acta Physica Hungarica B 26, 365-389 (2006). arXiv: quant-ph/0611010 .

[3] Varró S, Irreducible decomposition of Gaussian distributions and the spectrum of black-body radiation. Physica Scripta 75, 160-169 (2007). arXiv: quant-ph/0610184 . 

[4] Varró S, The digital randomness of black-body radiation. Journal of Physics Conference Series 414, 012041 (2013). arXiv:1301.1997 [quant-ph] .

[5] Besicovitch A S, On the sum of digits of real numbers represented in the dyadic system. (On sets of fractional dimensions II.) Mathematische Annalen 110, 321-330 (1935). 

[6] Varró S, Planck entropy expressed by the Hausdorff dimension of the set of average excitation degrees of a two-level atom in thermal equilibrium. Talk S7.4.1.  presented at LPHYS’18  [27th International Laser Physics Workshop, 16-20 July 2018., Nottingham, UK]

OPTOMAN will present latest developments in IBS coatings for extreme applications – new type of mirrors without discoloration for ultrafast laser applications, mirrors for multi-pass cell applications. New developments in UV and mid-IR ranges.

The high-intensity light pulses used in mutiphoton experiments come from amplifiers, and these pulses contain quite strong (unwanted) pre-pulses, or ‘pedestals’. The main source of the pedestal is said to be the amplified spontaneous emission (ASE) of the amplifying medium. Since the photon statistics of the ASE is different from that of the main pulse, the study of multiphoton processes taking place in a pedestal may be interesting, both in theory and in experiments. This is even so, because in the last couple of years there has been a growing activity in investigating how, and to what extent the quantum nature of light manifest itself in strong-field laser-matter interactions? It seems that quantum optical considerations will receive an increasing importance in the interpretation of certain experimental results on high-order processes, like quantum correlations and photon counting measurements [1-5]. 

Recently we have worked out a general quantum optical theory of multiphoton processes [6], which seems to be capable of answering the above question in several cases. In the present talk we shall briefly explain the main ingredients of this theory, and deal with the possible role of photon statistics in high-harmonic generation. 

On the basis of this general theory [6], and with the help of our new results on squeezing transitions [7], we have also calculated the transition probabilities of electron excitation and scattering in the field of a ‘pedestal’. The larger part of the talk will be devoted to the discussion of the main characteristics of such multiphoton processes. 

References.

[1] Tsatrafyllis N, Kühn S, Dumergue M, Földi P, Kahaly S, Cormier E, Gonoskov I A, Kiss B, Varjú K, Varró S and Tzallas P, Sub-cycle quantum electrodynamics in strongly laser-driven semiconductors. Physical Review Letters 122, 193602 (2019).

[2] Gorlach, A.; Neufeld, O.; Rivera, N.; Cohen, O.; Kaminer, I. The quantum-optical nature of high harmonic generation. Nat. Commun. 2020, 11, 4598.

[3] Lewenstein, M.; Ciappina, M.F.; Pisanty, E.; Rivera-Dean, J.; Lamprou, T.; Tzallas, P. The quantum nature of light in high harmonic generation. (2020). arXiv: 2008.10221.

[4] Földi P, Magashegyi I, Gombkötő Á and Varró S, Describing high-order harmonic generation using quantum optical models. Photonics 2021, 8, 263. (2021).

[5] Gombkötő Á, Földi P, Varró S, A quantum optical description of photon statistics and cross-correlations in high harmonic generation. Physical Review A 104, 033703 (2021). 

[6] Varró S, Quantum optical aspects of high-harmonic generation. Photonics 8, 269 (2021) [https://doi.org/10.3390/photonics8070269 ]. 

[7] Varró S, Coherent and incoherent superposition of transition matrix elements of the squeezing operator.  Journal of Physics Conf. Ser. (2022). E-print: arXiv: 2112.08430 [quant-ph].

A long awaiting dream for researchers in the field of chemistry, material science and biology is understanding of the ultrafast charge migration in molecular systems. The extracted information on charge migration dynamics, will ultimately assist in engineering of new materials for photo-voltaic applications, photo-responsive drugs, photo-catalysis, determining fragmentation channel and understand radiation damage or photo-protective response to radiation therapy. To move in this direction, using the single particle Green's function Non-dyson ADC(3) method [1], we study the influence of tautomeric sites and methyl group on the charge migration dynamics in Uracil and Thymine nucleobases. Our results manifest that, the charge migration dynamics can be influenced and tailored by the site of tautomeric hydrogen, presence of methyl group and by targeting highly correlated molecular orbitals. Tautomerisation is important for the biologically important systems as it is interpreted to be one of the photo-protective response mechanism to radiation [2], in living organisms. The analysis also reveal that the maximum flux time (within 100 as) i.e., time when atomic site starts to donate or receive electronic density, shows the influence of electronegativity of atoms in the molecular systems. Thus, present study could be utilized to understand the possible response to post-radiation, and could be of interest to design photo-responsive materials.

[1] J. Schirmer, A. B. Trofimov, and G. Stelter. J. Chem. Phys. 109.12 (1998), pp. 4734–4744.

[2] D. Lapotko, E. Lukianova, M. Potapnev, O. Aleinikova, A. Oraevsky, Cancer Lett., 239, (2006), pp. 36 - 45

The problems of tunneling time and tunnel exit momentum in strong-field ionization are of outstanding importance regarding both quantum theory and attosecond metrology. Based on a phase space analysis and the relevant energy distribution, we reveal the importance of quantum interference between tunneling and over-the-barrier pathways of escape during the liberation of a single atomic electron by a linearly polarized laser pulse, which explains experimentally measured non-zero values of the tunnel exit momentum. We suggest and justify improved initial conditions for a classical particle approximation of strong-field ionization, based on the quantum momentum function, and we show how to reconstruct them from the detected momentum of an escaped electron.

Hexagonal boron nitride (h-BN) has attracted a vivid interest, partly because this material is a very good insulating support for graphene nanoelectronics (and is also a graphene analogue), only weakly influencing the properties of graphene. Due to the weak metal-nitride interaction, the h-BN monolayer is planar on the close-packed surfaces of coinage metals (Cu, Ag, Au). Thereby, between gold and h-BN it was not possible to grow a continuous monolayer of the BN before the onset of the second layer. On the other hand, the h-BN monolayer has a periodically corrugated structure on Rh(111), so-called ‘‘nanomesh’’ due to the lattice mismatch and the relatively strong interaction between h-BN and the metal. It has two specific regions, pores and wires depending on the layer distance from the surface. The nanomesh surface is a good template for metal nanoclusters and organic molecules. Since literature data about h-BN growth on alloys is very scarce, in the present study we prepared h-BN on gold-rhodium surface alloys with a different gold content (0, 0.95, 1.15, 1.8 monolayers). The central aim was to measure and analyze the valence band k-space region of these surfaces with the NanoESCA, using its internal light sources. The Au layer was prepared on the clean Rh(111) surface by metal evaporation and annealing (1050 K). Then hexagonal BN was synthetized on top, decomposing borazine (B₃N₃H₆) at 1050 K. The formation of the nanomesh structure resulted in the splitting of the s and p bands of h-BN into various branches, and this phenomenon was influenced by the Au content. Interestingly, rhodium features were influenced by the presence of h-BN even in the energy range close to the Fermi level, where the insulating h-BN has no states: replicas of the original features appear on constant energy slices shifted by the superlattice reciprocal vector. With the help of X-ray photoelectron spectroscopy (XPS) we revealed the h-BN can act as a template not only for species adsorbed on top of it but also for the interfacing layer below it.

Hot electron generation upon the excitation of surface plasmon polaritons plays a key role in emerging applications such as photocatalysis, light harvesting and sensorics. In this seminar talk, we will discuss the time evolution and in depth distribution of such hot carriers. For this purpose, we demonstrate an experimental method to directly measure plasmon-associated changes in dielectric properties of metallic surfaces utilizing spectroscopic ellipsometry. Monitoring these changes in the dielectric function allows us to follow changes in the electron distribution. Pump-probe and continuous wave experiments revealed different aspects of plasmon generation. Pump-probe ellipsometric approach with <100 fs resolution enabled us to identify the different stages of plasmon decay through which electrons are scattered among each other and interact with the lattice. For continuous wave illumination, hot electrons are always present in the system, therefore the spectral signature of a hot electron population and its spatial location within the plasmonic thin film can be determined using the retrieved dielectric function from cw measurements.

The study of the physical bases of stimulated emission and black-body radiation have been closely related from the very beginning. We feel it justified to devote some time for their joint analysis, in particular, in the present year, when we celebrate the 60th anniversary of the invention of the LASER (Light Amplification by Stimulated Emission of Radiation). Moreover, one should also keep in mind that in the course of his work on black-body radiation,  the elementary quantum of action h was discovered by Planck just 120 years ago. In the present talk, though we shall highlight some moments in the development of the laser during the past 60 years, but the emphasis shall be put on the fundamental aspects. Our purpose is twofold; on one hand we discuss some lesser known historical facts concerning the stimulated emission of radiation as appeared in the works of Planck (1911) and Einstein (1916). On the other hand, we present our recent results; the first of which is a new phenomenological derivation of the entropy of a Planckian oscillator. Concerning the probabilistic description,  we will show how to build up a correspondence between entropy and the fractal dimension of the relative frequencies of the excitation of a Bohr atom in thermal equilibrium.

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Recently the generation of trains [1] and isolated[2] attosecond pulses was demonstrated at Free Electron Lasers (FELs) operating in the extreme ultraviolet (XUV) and soft X-ray spectral

range. FEL-driven attosecond sources present important advantages with respect to table-top

attosecond sources based on high-order harmonic generation, including high-energies per pulse (typically in the microjoule range), tunability of the photon energy and shaping capability (in the case of train of attosecond pulses). On the other hand, these sources present significant drawbacks such as temporal jitter between the XUV waveform and the optical/infrared laser and lowrepetition

rates. In this talk I will show how the control of the relative phase between the harmonics

achieved at FERMI [3] gives access to its characterization, by implementing a correlation-based analysis of the photoelectron spectra generated by the combination of the attosecond and infrared pulses. I will also present novel ideas on how to extend the correlation-analysis tools for extending attosecond metrology to situations in which sub-cycle synchronization between the attosecond waveform and the infrared field is not guaranteed.

References

[1] P. K. Maroju et al. Attosecond pulse shaping using a seeded free-electron Laser, Nature 578, 386-391 (2020).

[2] J. Duris et al. Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser, Nature Photon. 14, 30-36 (2020).

[3] K. C. Prince et al. Coherent control with a short-wavelength free-electron laser, Nature Photon. 10, 176-179 (2016).

Plasma oscillation is attractive as a radiation source, since the frequency can be easily controlled just by changing the plasma density and the amplitude can be made arbitrarily high (up to the wavebreaking limit) as there is no damage threshold in plasmas. Unfortunately it is never trivial to convert the electrostatic plasma oscillation to an electromagnetic wave. There are several physical reasons for that; for an instance, the plasma oscillation usually appears as a traveling wave (wakefield or Langmuir wave), which does not phase-match with the electromagnetic waves inside the plasma. With the aid of external magnetic field or non-uniformity of the plasma or linear and nonlinear scattering processes, the energy of the plasma wave can be partially converted to electromagnetic energy. Recently we reported a totally different approach to obtain an electromagnetic emission from the plasma oscillation. The idea is generating a localized bunch of electrons that oscillate in-phase, which we identify as a plasma dipole oscillator (PDO), by colliding two detuned laser pulses in plasma. From one-, two- and three-dimensional particle-in-cell (PIC) simulations, it is verified that the PDO oscillates at the local plasma frequency and emits a strong dipole radiation at the same frequency. The electrostatic-electromagnetic energy conversion does not require any complicated linear and nonlinear processes or external magnetic field. This property of the PDO makes it useful as a light source in the terahertz band (Kwon et al., Sci. Rep. 2018) and also as a novel diagnostic method for non-uniform plasma density (Kylychbekov et al., PSST 2020).  The PDO in a strongly magnetized plasma has even richer physics; diverse spectral modes such as upper-hybrid and R, L cutoffs of X-modes exist together, and the polarization of the radiation also changes with direction of the emission.  As the spectral density can be made high at a desired frequency, the PDO-THz can be potentially useful in THz electron acceleration, and other applications where narrowband THz is required. It is found that the PDO-emission and coherent cosmic radio bursts share several common features, making the PDO an interesting subject of lab-spacephysics or lab-astrophysics.

Optosigma Europe -  part of the Optosigma Group - is specialised in manufacturing of optics, optomechanics and translation stages. The Company’s products include optics, optomechanics, manual and motorised stages, optical tables, fiber optics, light sources, laser analytics, and laser safety products. Standard and customised (shape, coatings, assembies, substrates, systems, etc) pruduct are available to find the best solution for the customer.

I.             Company facts

II.            Scientific CCD Cameras/ Sensor Basics

III.          Scientific cameras for NIR, VIS and UV applications

IV.          Scientific cameras for X-ray, EUV, and VUV applications

V.           New Sensor Technologies - Superresolution Cameras & sCMOS

VI.          greateyes inspection systems

Georg Korn - Opening (2-5 mins)

Minister László Palkovics - Greetings (2-5 mins)

Gerard Mourou - Greetings (2-5 mins) 

Toshi Tajima - Summary of the Project (10 mins)

Karoly Osvay / Gabor Szabo  - Proton acceleration from ultrathin foils with 11 fs pulses – preliminary results (15 mins)

Allen Weeks - EU level initiative (10mins)

Georg Korn - Future Plan (10mins)

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High power and high repetition rate lasers are critical for many applications in the physical, chemical, and biological sciences. Previously, laser sources from x-ray to THz were driven from Ti:Sapphire lasers at 800 nm with limited bandwidth (Fourier limited pulse of ~20 fs), and  more importantly limited power levels; power levels ~40 W and above require large complex cooling systems. Optical parametric chirped-pulse amplification (OPCPA) together with bulk crystal white-light-generation (WLG) opens up the possibility high power lasers (well above 100 W), with wavelength tunable and broadband (for example, < 10 fs at 800 nm), requiring no complex cooling with a compact design. Previous thermal studies of nonlinear crystals – BBO, LBO and KTA – demonstrated the possibility of using these crystals for high power applications at 800 nm and 1.5 µm. Recently, 100 W-level OPCPAs are now commercially available from Class 5 Photonics GmbH using BBO at 800 nm and KTA with a tunable range 1.45 – 2 µm.

Femtosecond direct laser writing, also known as two-photon polymerization, is a photolithographic method that enables the fabrication of 3D microstructures with submicron resolution. The possibility of creating arbitrary shaped 3D microstructures provides a general advantage for studying the physics and biology of the microworld in more detail. In this talk I will present experiments and applications relying on microstructures created with two-photon polymerization [1,2,3].

[1] Hydrodynamic synchronization of light driven microrotors, R Di Leonardo, A Búzás, L Kelemen, G Vizsnyiczai, L Oroszi, P Ormos, Physical review letters 109 (3), 034104

[2] Multiview microscopy of single cells through microstructure-based indirect optical manipulation, Vizsnyiczai, G., Búzás, A., Aekbote, B. L., Fekete, T., Grexa, I., Ormos, P., & Kelemen, L. (2020). Biomedical Optics Express, 11(2), 945-962.

[3] A transition to stable 1D swimming enhances E. coli motility through narrow channels, G Vizsnyiczai, G Frangipane, F Saglimbeni, S Bianchi, D Dell’Arciprete, and R Di Leonardo, Under review in Nature Communications.

Nowadays, ion acceleration driven by super intense laser pulses is one of the most interesting fields of research because of potential applications such as cancer therapy, fast ignition, ion imagining etc. Intense laser pulses, due to possessing very strong electric and magnetic fields, are capable of accelerating ions to high energies over very short distances (the acceleration gradients obtained in plasmas are 100–1000 GeV/m, orders of magnitude higher than 10–100 MeV/m typical values of conventional accelerators), allowing for what is called as a tabletop ion accelerator. This paper is an experimental study of the interaction of the DRACO high power laser with solid targets. Since the temporal structure of the laser pulse affects the laser–matter interaction and change the condition of the main pulse interaction with the target, cleaning laser pulse and enhancing temporal laser contrast is necessary before starting experiment. Then, in the experiment, the intrinsic temporal contrast of the laser pulses was improved (two to three orders of magnitude) by using a re-collimating single plasma mirror before the pulses were focused onto thin plastic and gold foil targets under oblique incidence. Results show proton and carbon ions, accelerated in the target normal sheath acceleration (TNSA) regime. Origin of accelerating protons is contaminant  layers of water vapor or hydrocarbon behind the surface of target or oil. The highest proton cut-off energy was 32 MeV obtained from 95nm thin plastic targets and 25 MeV from 50 nm gold targets. Experimental evidence have not shown any heavy gold ions acceleration during experiment, which is due to screening effect of light ions acceleration.

OPTOMAN as a supplier for highly customized and application optimized IBS coated components will be introduced. Various coating technologies, advantages of IBS versus other available options. Having successfully collaborated with various research centers, such as DESY in Germany, HiLASE in Check Republic etc., there is hope to find common projects with ELI-ALPS as well.

-              Research and Intellectual Property („IP”)

-              Why to protect IP ?

-              The case of Rubic’ s cube

-              Types of IP Publication of the scientific results or/and getting IP protection

-              What is a patent?

-              What can be patented? What cannot be patented?

-              General patentability criteria  (novelty, inventive step, industrial applicability)

-              Preventing the re-invention of the existing inventions (Patent Information the huge collection of technical and scientific knowledge)

Micrometer scale metasurfaces are widely explored as various devices and components serving the terahertz technology. Because of the excellent design flexibility, these metasurface based terahertz devices have uniques advantages and general design methodology, which continuously attracts researchers attention. This talk will present the series of terahertz metasurfaces designed to control the amplitude and phase of terahertz waves, which were conducted in Center for Terahertz Waves, Tianjin University.  These devices include terahertz lenses, modulators, cloak carpets and slow wave components based on plasmon induced transparency (PIT). In addition, recent results on metamaterial assisted photoconductive antennas will be discussed. 

The Centro de Láseres Pulsados is a key Spanish User facility founded by the Ministry of Science, the region of Castilla y León and the University of Salamanca; it is included in the strategic Roadmap of Unique Scientific and Technical Infrastructures (ICTS) in Spain  and its main mission is to promote scientific and technological development by offering national and international user access.

The Uniqueness of CLPU is the multi Terawatt laser system VEGA composed by three independent and synchronised 30 fs long, Ti:Sa based laser pulses of 1 PW (VEGA-3), 200 TW (VEGA-2) and 20 TW (VEGA-1) working at a repetition rate up to 10 Hz.

The VEGA2 laser system has been successfully commissioned in 2016-2017 in two different configurations respectively for electron and proton. The first call for user has been run in 2018 with several International recognised research teams. The PW laser (VEGA-3) is now fully operative, and commissioning experiments will start in 2019. A new call for users has been issued offering VEGA-2, VEGA-3, and VEGA-2-based secondary sources (electrons, protons and X-rays).  The first VEGA-3 experiment is planned for September 2019.

The combination of laser intensity, short duration and repetition rate offered by VEGA pave the way for new exiting experiments but also represent a scientific and technological challenge for what concern Targetry and Diagnostic techniques.

Here a first report on the scientific activities of the last years at CLPU is presented focused on:

i)             The first  commissioning campaign

ii)            The  first user access campaign

iii)           The scientific program for targetry and diagnostic development @ HRR

Overview of propsed transmutator driven by fusion neutrons (at 14.1 MeV) in a solution of molten salt (FLiBe/FLiNaK), with a further focus on neutronics simulation. Seminar to cover: A brief review of the state of nuclear waste policy and the need to develop waste management technologies (toilet science). The proposed transmutator, utilizing laser driven ion acceleration triggered fusion neutron sources, and transmutation in minor actide carrying molten salt medium. Basics of nuclear simulation through transport and depletion. Linkage code development and future directions with an emphasis on AI optimization.

Substrate-transferred crystalline coatings exhibit tenfold decrease in Brownian noise and 30 times higher thermal conductivity (20-30 Wm^-1K^-1) compared to IBS coatings. The ultra-low noise character of these semiconductor coatings is especially used for laser stabilization in optical clocks. Additionally, crystalline coatings have superior performance in the mid-IR spectral range exhibiting excess losses down to 50 ppm. Coupled with direct bonding to thermally-optimized substrates, this technology enables significant performance enhancements in high-power solid-state disk and semiconductor laser systems. In collaborative efforts we show that our direct bonding technology can not only enhance the thermal management of high-power laser systems, but also the mechanical rigidity and surface quality of the bonded elements.

-          About Springer Nature

-          Copyright, Authors’ Right, Open Access

-          Journal Publishing

-          Publication Ethics – Research Integrity

-          Book Publishing

In the first part we have shown that the four potential of electromagnetic fields in a plasma medium can be considered as a massive vector field, where the mass is proportional with the plasma frequency. The plane waves of this »Lánczos-Proca fields« have three orthogonal polarizatons, whose amplitudes satisfy the Klein-Gordon equation. The expression „Klein-Gordon radio” in the title of our talks has been borrowed from the paper by Crandall and Wheeler [1], devoted to the study on a dynamical bound of photon mass. These authors presented the peculiarities of wave propagation in free space, such as the appearance of wake-fields and the special Doppler effect of radio signals from a rapidly receding massy-photon transmitter. We have indicated that similar phenomena are also relevant in the so-called laser wake-field accelerators and in the generation of high harmonics (and attosecond pulses) in a plasma environment. In this second part of the presentation, on the basis of recently found new exact solutions of the relativistic wave equations of charged particles [2], we also show that very high contrast density modulations are generated, serving as »quantum bubbles« to accelerate electrons [3]. We also consider exact analytic solutions of the relativistic equation of motion of a point electron interacting with a high-intensity laser field in vacuum and in a plasma medium [4], and compare the particle dynamics and the radiation properties [5] in these two cases. 
 
References:
[1] Crandall R E, Wheeler N A, Klein-Gordon radio and the problem of photon mass. Nuovo Cim. 80B, 231 (1984).
[2] Varró S, New exact solutions of the Klein-Gordon and Dirac equations of a charged particle propagating in a strong laser field in an underdense plasma. Nucl. Instr. and Methods in Phys. Research A  740, 280-283 (2014).
[3] Varró S, Quantum description of relativistic charged particles interacting with a strong laser field in a plasma, represented by Lanczos-Proca vector bosons. Talk presented at EUCALL Joint Foresight Topical Workshop: Theory and Simulation of Photon-Matter Interactions [ELI-ALPS, 1-6 July 2018, Szeged, Hungary].
[4]Pocsai M A, Varró S and Barna I F, Electron acceleration in underdense plasmas described with a classical effective theory. Laser and Particle Beams 33, 307-313 (2015). E-print: arXiv: 1406.6310 [nucl-th].
[5] Hack Sz, Varró S and Czirják A, Carrier-envelope phase controlled isolated attosecond pulses in the nm wavelength range, based on coherent nonlinear Thomson backscattering. New J. Phys. 20, 073043 (2018).

Web of Science Core Collection is the largest editorially curated citation database.  During this presentation we will show, how Web of Science can help you identify discoveries and research useful to advance your own path to innovation and discovery. We will also show how you can optimize the use of Web of Science, Endnote, Kopernio and other tools available to experience a more efficient workflow, from reading to publishing papers.

In the present talk,  first we show that the four potential of electromagnetic fields in a plasma medium can be considered as a massive vector boson field, where the mass is proportional with the plasma frequency. Similar vector fields has long been known in quantum electrodynamics from the works of Lánczos [1] and Proca [2], but these do not rely on plasma considerations. The „mass-generation mechanism” has been described by Anderson [3] in solid state physics, and the research in particle physics on this subject has recently culminated in the detection of the Higgs particle [4].

The plane waves of the »Lánczos-Proca fields« have three orthogonal polarizatons, whose amplitudes satisfy the Klein-Gordon equation. The expression „Klein-Gordon radio” in the title of the present talk has been borrowed from the paper by Crandall and Wheeler [5], devoted to the study of a dynamical bound on photon mass. These authors presented the peculiarities of wave propagation in free space, such as the appearance of wake-fields and the special Doppler effect of radio signals from a rapidly receding massy-photon transmitter. We show that similar phenomena are also relevant in the so-called laser wake-field accelerators and in the generation of high harmonics (and attosecond pulses) by relativistic electrons, interacting with extremely high intensity laser fields in a plasma environment. On the basis of recently found new exact solutions of the relativistic wave equations of charged particles [6], we also show that very high contrast density modulations are generated, serving as »quantum bubbles« to accelerate electrons [7]. In the last part of the talk we consider exact analytic solutions of the relativistic equation of motion of a point electron interacting with a high-intensity laser field in vacuum [8] and in a plasma medium, and compare the particle dynamics (laser acceleration) and the radiation properties (attosecond light pulse generation) in these two cases. 

 

References.

[1] Lánczos C, Die tensoranalytischen Beziehungen der Diracschen Gleichung. Z. für Physik 57, 447 (1929).

[2] Proca A, Sur la théorie ondulatoire des électrons positifs et négatifs. J. Phys. Radium 7, 347-353 (1936).

[3] Anderson P W, Plasmons, gauge invariance, and mass. Phys. Rev. 130, 439-442 (1963).

[4] Higgs P W, Evading the Goldstone theorem. Ann. Phys. (Berlin) 526, 211-213 (2014). [Nobel Lecture, 8 December 2013.]

[5] Crandall R E, Wheeler N A, Klein-Gordon radio and the problem of photon mass. Nuovo Cim. 80B, 231-242 (1984).

[6] Varró S, New exact solutions of the Klein-Gordon and Dirac equations of a charged particle propagating in a strong laser field in an underdense plasma. Nucl. Instr. and Methods in Phys. Research A  740, 280-283 (2014).

[7] Varró S, Quantum description of relativistic charged particles interacting with a strong laser field in a plasma, represented by Lanczos-Proca vector bosons. Talk presented at EUCALL Joint Foresight Topical Workshop: Theory and Simulation of Photon-Matter Interactions [ELI-ALPS, 1-6 July 2018, Szeged, Hungary].

[8] Hack Sz, Varró S and Czirják A, Carrier-envelope phase controlled isolated attosecond pulses in the nm wavelength range, based on coherent nonlinear Thomson backscattering. New J. Phys. 20, 073043 (2018).

Have you ever wondered who writes the description on the wine label sold in supermarkets? If done by experts, they are called sommeliers. They are professional wine experts with wide range of knowledge about wine service and pairing it with food.

One of the hardest things is to master blind tasting. Blind tasting is when a person is served a glass of wine (or other alcohol) and his task is to describe its characteristics, like color, body, acidity, taste, smell etc. Depending on the difficulty of the tasting the person might be further requested to guess the grape variety, vintage, country of origin etc. of that wine based on the features he just described.

This sounds much like a machine learning task: based on a given description of wine characteristics decide what grape was used to produce the wine, in which country, what vintage etc.

The seminar will present a simple application of how data mining and simple supervised machine learning techniques can be applied to create a simple but still powerful code to guess the grape variety of which a bottle of wine was made from.

This work presents an analytic angular differential cross section formula for the electromagnetic radiation field-assisted electron scattering on impurities in semiconductors. These impurities are approximated with various model potentials. The scattered electrons are described with the well-known Volkov wave function, which has been used to describe strong laser field matter interaction for more than half a century, which exactly describes the interaction of the electron with the external oscillating field. These calculations show that the electron conductance in a semiconductor could be enhanced by an order of magnitude if an infrared electromagnetic field is present with 10^11 W/cm^2 < I <10^13 W/cm2^ intensity.

Reference: Imre Ferenc Barna, Mihály András Pocsai, and Sándor Varró, Eur. Phys. J. Appl. Phys. 84, 20101 (2018) https://www.kfki.hu/~barnai/semicond_barna_ApplPhys2018.pdf

SG-II facility consists of four sets of lasers, including the nanosecond, picosecond and femtosecond duration pulses. Researchers can conduct varies physical experiments, such as Inertial Confinement Fusion, laboratory astrophysics and particle acceleration. In the first part of the presentation, we mainly describe our experiments conducted on the SGII facility. It includes the study of suprathermal electrons produced by laser-plasma instabilities, the evolution of filaments and associated magnetic fields produced by Weibel instability in two counterstreaming laser plasmas and proton imaging by the picosecond petawatt laser pulse. In the second part, we will describe our target chamber size and the current diagnostics at the facility, which will help external research teams carry out experiments.

Refractive lenses cannot be applied to short-wavelength region by their inherent strong absorption. Relatively, diffractive optical element (DOE) can be used for EUV and soft X-ray focusing and imaging. As a representative of classical DOE, photon sieve derived from the traditional Fresnel zone plate was first proposed in 2001. Furthermore, it can achieve higher resolution on the same component scale. Compared with the monofocal photon sieve, we proposed Greek-ladder sieves to generate three-dimensional array diffraction-limited foci in 2015. Based on Greek-ladder sieve, we here give a brief overview of our recent research on the phase-shifting X-ray digital holography, multiplanar imaging with different point spread functions and phase-contrast imaging, and do some exploration and research on the meter-scale wavefront measurement.

As the major pioneer devoted to high-power laser technology and inertial confinement fusion (ICF) research in China, the National Laboratory on High Power Laser and Physics (NLHPLP) in Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences has established a multifunctional high power laser experimental platform, which can provide important experimental capabilities by combining different pulse widths of nanosecond, picosecond, and femtosecond scales. We will introduce this multifunctional experimental platform, including the SG-II laser facility, SG-II 9th beam, SG-II upgrade (SG-II UP) facility, and SG-II 5 PW facility, and present the key technologies for the eight-beam nanosecond laser system, the picosecond petawatt system, and femtosecond multi-petawatt system, which have been developed to ensure the performance of the facilities. The multifunctional high power laser experimental platform at NLHPLP is operational and available for interested scientists studying ICF and a broad range of high-energy-density physics. Both the physics experiment cooperation and the laser technology collaboration are welcomed at NLHPLP.

Finite terms Hylleraas- and Kinoshita-type variational wave functions are considered for three-body systems.

For calculation of the energies the stochastic variational method is applied. This approach leads to significant decrease of the number of terms present in the trial wave function.

In Coulombic case local properties of wave functions are restricted by the Kato's cusp conditions. It is showed that Kato's cusp conditions restrict the possible terms in variational calculations. Constraints for the linear expansion coefficients are also derived and a recursion type solution is given. Local and global properties of wave functions with correct cusp conditions are studied, finally the double-electron photoionization is considered.

In our latest study new sets of functions with arbitrary large finite cardinality are constructed for two-electron atoms. Functions from these sets exactly satisfy the Kato's cusp conditions. The new functions are special linear combinations of Hylleraas- and/or Kinoshita-type terms. Standard variational calculation, leading to matrix eigenvalue problem,  can be carried out to calculate the energies of the system.

There is no need for optimization with constraints to satisfy the cusp conditions.

Today’s materials research is unthinkable without the analytical tools that allow studying structure and dynamics from the subatomic to the macroscopic level.

Among those tools neutron scattering occupies a prominent position given the particular properties of the neutron as a probe.

Recent progress in instrumentation has contributed to reinforcing the role of neutron scattering making it accessible to an even wider range of users.

In this presentation modern neutron scattering as a tool for materials investigations will be briefly introduced. Then, by highlighting recent scientific results, the scientific potential of neutron scattering will be illustrated. The topics will range from fundamental questions in magnetism to structural biology.

In order to make the talk accessible to a broad audience the accent will be placed on the scientific impact of the experiments avoiding technical details.

Ultrafast Coherent Multidimensional Electronic Spectroscopic belongs to the family of ultrafast nonlinear optical spectroscopy, and is an improvement over conventional ultrafast pump probe (transient absorption) spectroscopy, as it has the ability to resolve both the excitation and detection frequencies in an ultrafast experiment while still maintaining femtosecond time resolution. We will describe our efforts in the development and applications of these techniques to the study of excitation energy transfer (EET) processes in photosynthetic light-harvesting antenna systems.

Laser-plasma particle acceleration is a non-traditional acceleration technique that could lead to a significant downsizing of future high-energy accelerators [1-2].  Recently we conducted laser-plasma electron acceleration research in Shanghai, China. Experiments were based upon a newly-installed 200 TW 30 fs Ti:sapphire laser. We performed a few types of laser wakefield acceleration (LWFA) experiments; the first was based on the self-injection of electrons in 4 mm long He plasma interacted with 30 TW laser pulses (a0 ~1.2). We observed ~120 MeV electron beams with ~ 40 % energy-spread [3]. In order to improve the electron beams we conducted a second type of experiments where we employed the ionization-injection mechanism, by which we observed a significant enhancement of the beam energy up to 400 MeV and a reduction of the energy-spread to 4% [4]. In a follow-up experiment on ionization injection, and in order to boost the electron energy and quality, we employed ~ 120 TW laser pulses and 1 cm-scale plasma. Here we observed narrow energy-spread beams (7 %) with 1.2 giga-electron volts peak energy; see Fig. 1 [5]. The experimental results and the involved physics were all verified by 3D-PIC simulations using OSIRIS code. Additionally, we have measured the emission of synchrotron x-rays (due to the betatron oscillations) from the accelerated relativistic electrons; few mrad, hard x-ray beams with energy up to 100 keV were observed [6]. Finally, by the electrodynamics process of bremsstrahlung we have observed electron-position pairs with energies of 100 MeV and 10 MeV gamma ray beams [7]. In my talk, some of those topics [8] will be discussed in details.

The catalytic activity of proteins is a function of structural changes. Very often these are as minute as protonation changes, hydrogen bonding changes and amino acid side chain reorientations. To resolve these, a methodology is afforded that not only provides the molecular sensitivity but allows to trace the sequence of these hierarchical reactions at the same time. I will showcase results from time-resolved IR spectroscopy [1,2] which was applied to channelrhodopsin [3].  Channelrhodopsin represents the first light-activated ion channel to found the basis of the new and exciting field of optogenetics [4]. I shall also provide an outlook towards novel experimental approaches like THz pump / IR probe spectroscopy or near-field IR nanoscopy (see figure below) that are currently developed in my lab [5]. We believe that some of these approaches have the potential to provide new science.

FERMI is an externally seeded FEL source, based on the high-gain harmonic generation scheme (HGHG). FERMI has two FEL line, FEL-1, which covers the wavelength range between 100 and 17 nm and FEL-2 in the range between 17 and 4 nm. The shortest pulses delivered by FEL-1 ad FEL-2 have respectively a duration of 40-90 fs and 20-30 fs according to pulse duration scaling with the wavelength.

Controlling pulse duration, and, more generally, the temporal intensity profile of free-electron laser (FEL) pulses, would permit to resolve faster processes, as electronic rearrangements and exploration of electronic motions and nuclear phenomena. This possibility would extend the experiments targeted by FERMI.

In this talk I present the methods that could be used to reduce the pulse length in FERMI and explain how we measure the pulse shape of an extreme ultraviolet externally seeded FEL operating in high-gain harmonic generation mode.

Nanoplasmas formed from doped helium nanodroplets by irradiation with intense laser pulses feature peculiar properties. In the NIR range, a helium ionization avalanche is triggered by tunnel ionization of the dopant cluster at comparatively low light intensities (~1014 W/cm2). Subsequent light absorption is enhanced by resonances due to nanoplasma anisotropies [PRL 107, 173402 (2011)] and expansion [NJP 14 075016 (2012)]. Consequently, dopant and helium atoms charge up to high charge states [J. Mod. Opt. 64, 1061 (2017)], and energetic ions and electrons are emitted by Coulomb explosion. Surprisingly, recent single-shot velocity-map images of nanoplasma electrons display sharp electron energies peaked at ~1 eV energies. Prospects for probing helium nanoplasmas driven by intense MIR and XUV laser pulses are discussed.

An existing CPA high power laser pulse such as a commercially available PW laser could be readily converted into a single-cycled laser pulse in the 10PW regime without significant loss of energy through the compression. We will describe a way to attain this goal heralding a new set of fascinating applications to science, including medicine, environmental and material science. These include a laser ion accelerator, called single-cycle laser acceleration (SCLA), and bow wake electron acceleration. In addition, in the X-ray regime, single-cycled laser pulses may be readily converted through relativistic compression into a single cycled, X-ray laser pulse. We argue that it could be the quickest and very innovative way to ascend to the EW (Exawatt) and zs (zeptosecond) regime. In this talk we will cover the generation of single-cycled pulse and its numerous and revolutionary applications

An overview discussion about Spectra-Physics Lasers, capabilities, products and applications.  Emphasis on laser technologies designed for research laboratories, particularly large laser infrastructure facilities including pump lasers, short pulse ultrafast oscillators and amplifiers and advanced technologies such as CEP and laser synchronization accessories.

National Energetics is developing high intensity lasers from few tens of Terawatts to 10 Petawatts for scientific applications. These are CPA laser systems based on classic Ti:Sapphire as well as mixed glass, using novel technology for augmented repetition rate at kJ level. Moreover, NE is also providing full remote controls system integrated with the infrastructure.

The presentation will focus on the 10 PW (1500J in 150 fs at 1 shot/minute) laser under construction for ELI-Beamlines. This is a hybrid system with a high contrast OPCPA front-end (4J@5Hz) with spectral shaping capabilities followed by Nd doped-glass amplification for high output energy with split-disk, liquid-cooled technology.

Characteristics of high temporal contrast hybrid system based on short pulse OPCA and classic Ti:Sa amplifiers at 800 nm will also be presented.

By deriving the correct formula of the spectral energy density of black-body radiation, Max Planck (1858-1947) discovered in 1900 the fourth fundamental physical constant h, the elementary quantum of action. On the occasion of Planck’s 160th birthday, and the centenary of his receiving the Nobel Prize, we keep track of Planck’s lesser known original thoughts concerning the black-body radiation problem. We point out that, Planck has also solved various other important problems in physics, and his methods and interpretations still may have relevance even today. We shall deal with his so-called second theory, which already contained the concept of induced emission and zero-point energy. We shall also show Planck’s original derivation of the natural system of units (Planck length, mass, time and temperature), which plays a distinguished role in cosmological physics.

The process of stimulated emission of radiation will be discussed, first in the context of black-body radiation, as it appeared more than hundred years ago in the works of Planck and Einstein. Later results concerning negative absorption, amplification and laser action will also be reviewed, including multiphoton processes which take place during the interaction of very-large-intensity lasers with various constituents of matter. These high-order processes result in large spectral broadening, and may lead to extreme temporal localization of the signals, thus yielding e.g. attosecond light pulses. The development of theoretical methods, interpretations and some examples of basic experimental achievements will be analysed. At the centenary of the first publications on the concept of stimulated emission, we attempt to build a bridge between the early thoughts and recent studies of attosecond and strong-field science.

[1] G. Rascol, H. Bachau, V. T. Tikhonchuk, H.-J. Kull, T. Ristow, Phys. Plasmas 13, 103108 (2006).

[2] H.-J. Kull, New J. Phys. 14, 055013 (2012).

[3] C. Baumann, H.-J. Kull, and G.M. Fraiman, Phys. Rev. A 92, 063420 (2015).

Single-photon wide-angle intereference phenomena have been studied theoretically for glass-diamond-oil and glass-diamond-air layered structures. As a single optical emitter (of wavelength e.g. 637 nm) onenitrogen-vacancy center (NV-center) has been assumed, which is placed close to the upper side of a diamond plate, and it was represented by a Hertzian dipole of arbitrary orientation. The interference fields can be imagined as resultans of superposition of rays emanating from the NV-center directly upwards and from those which are emanating downwards and undergo total internal reflection at the lower surface of the diamond plate of thicknesse.g. 0.1mm = 100000 nm [1]. The direct and the reflected rays recombine on the upper side, and we have proved that also the far-field interference pattern is sensitive to the vertical position of the NV-center (see illustration in Figure 1). As is seen, e.g. 2nm difference in distance of the emitter from the upper surface of the diamont results in an angular shift of order 0.01 degree of the pattern, which should already be a measurable effect.

Proceeding from the insights emerging from KS-MO analyses and the above BiaB, I will develop a strategy for creating a stable species involving a truly hypervalent, five-coordinate carbon atom. If successful, this quest would come down to a violation of the octet rule for carbon! One might conceive this also as "freezing" the SN2 transition state, turning the otherwise labile species into a stable equilibrium structure.

In our analysis particular attention has been paid to the role of the radiation reaction and of the time delay. There are several sources of time delay in the extended system: due to the angle of incidence of the impinging laser pulse and due to the propagation time between the two surface current sheets. In this presentation we show the analytic solution of the resulting coupled delay differential-difference system of equations when the three dielectrics have the same index of refraction, besides, we show some numerical studies of the most general case. The main emphasis is on the effect of the delay on the dynamics of the system.

Time-resolved photoemission experiments employing attosecond streaking of electrons emitted by an extended ultraviolet pump pulse and probed by a few-cycle near-infrared pulse found a time delay of about 100 as between photoelectrons from the conduction band and those from the 4f core level of tungsten. We present a microscopic simulation of the emission time and energy spectra employing a classical transport theory. Our calculations reproduced well both the emission spectra and streaking images. We found delay times near the lower bound of the experimental data.

Photoemission spectra feature also complex correlation satellite structures signifying the simultaneous excitation of single or multiple plasmons. The time delay of the plasmon satellites relative to the main line can be resolved in attosecond streaking experiments. Time-resolved photoemission thus provides the key to discriminate between intrinsic and extrinsic plasmon excitation. We demonstrate the determination of the branching ratio between intrinsic and extrinsic plasmon generation for simple metals.

Free Electron Lasers fulfill the need for soft and hard X-ray radiation with extremely high brilliance, a high degree of (transverse and longitudinal) coherence, and duration in the femtosecond time domain. FERMI covers the spectral range from 100 down to 4 nm and has been designed as a Users’ facility providing stable operation, high spectral purity, full tunability, variable polarization, and low timing jitter. Since the beginning of Users’ operation in December 2012, FERMI has received ~200 proposals, and allocated ~1/3 of them. Three beamlines are open to users (Diffraction and Projection Imaging; Elastic and Inelastic Scattering-TIMEX; Low Density Matter) and three more are scheduled to open in 2016.

The LDM beamline caters to the atomic-, molecular-, and cluster-physics community, offering an endstation for photoelectron, photoion, and photon-scattering spectroscopy of supersonic jets (notably, of helium droplets, which can be used to transport and cool large molecules). Beyond its standard spectrometers (Velocity Map Imaging; ion Time of Flight; photon scattering) the end-station has accommodated user-supplied instruments, for Users’ experiments as well as FERMI characterization experiments.

In this seminar I would discuss how astrophysical conditions3,4,5 can be recreated inside the laboratory elucidating the metrology schemes that lets us probe these systems. I would present a glimpse of how space-time resolved movies in µm-fs domain can unravel rich dynamics of electrons in relativistic laser plasma accelerators4,5.

References:

1. H. Vincenti, S. Monchocé, S. Kahaly, Ph. Martin and F. Quéré“Optical properties of relativistic plasma mirrors” - Nature Communications5, 3403 (2014)

2. F. Sylla, M. Veltcheva, S. Kahaly, A. Flacco and V. Malka “Development and characterizarion of very dense submillemetric gas jets for laser plasma interaction” - Review of Scientific Instruments 83, 033507 (2012)

3. F. Sylla, A. Flacco, S. Kahaly, M. Veltcheva, E. d’Humières, I. Andriyash, V. Tikhonchuk and V. Malka “Short intense laser pulse collapse in near-critical plasma ”- Physical review letters 110, 085001 (2013)

4. S. Kahaly, S. Mondal,G. Ravindra Kumar, S. Sengupta, A. Das and P.K. Kaw “Polarimetric detection of laser induced ultrashort magnetic pulses in overdense plasma” - Physics of Plasmas 16, 043114 (2009)

5. A. Flacco, J. Vieira, A. Lifschitz, F. Sylla, S. Kahaly, M. Veltcheva, L. O. Silva and V. Malka “Persistence of magnetic driven by relativistic electrons in a plasma”- Nature Physics 11, 409-413 (2015)

References:
[1] L.V. Keldysh, Sov. Phys.- JETP 20 (1965) 1307–14
[2] F. Krausz, M. Ivanov, Rev. Mod. Phys. 81 (2009) 163
[3] P.B. Corkum, Phys. Rev. Lett. 71 (1993) 1994
[4] M. Lewenstein et al., Phys. Rev. A 49 (1994) 2117
[5] M. Uiberacker et al., Nature 446 (2007) 627
[6] A.N. Pfeiffer et al., Phys. Rev. Lett. 109 (2012) 083002
[7] M.G. Benedict, et al., J. Phys. A: Math. Theor. 45 (2012) 085304
[8] A. Czirjak, et al., Opt. Com. 179 (2000) 29-38;
[9] A. Czirjak, et al., Phys. Scr. T153 (2013) 014013
[10] D.M. Heim et al., Phys. Lett. A 377 (2013) 1822–1825

We discuss the old problem of the quantum phase of an oscillator, which may represent for instance the phase of a quantized mode of the radiation field. After reviewing the main approaches have so far been applied to solve this problem, we shall offer a new solution. Our method is based on a new ‘polar decomposition’ of the quantum amplitude of the field components. With the help of this decomposition we have defined an analogon of the quantum saw-toothphase operator [1]. In the frame of the present approach a generalized spectral decomposition of the phase operator and projectors can be derived in a natural way, and they can be expressed by dyads of SU(1,1) coherent states [2]. Besides, we have found that these new sampling states (generalized projectors) for phase measurements can be generated by an experimentally realizable nonlinear interaction whose coupling strength depends on the intensity. The possible extension of our method to a multimode description may be useful in studying the quantum phase properties of extreme radiation fields, like few–cycle or attosecond light pulses.