LPHYS'15.    Plenary Speakers:

  1. Turbulence: New (Quantum) Twists to an Old Problem


    The aim of this talk is to review recent results in the study of turbulence in atomic Bose-Einstein condensates. Why turbulence, and why condensates?

    Turbulence is an old, notoriously difficult problem. It challenges physicists with difficulties such as nonlinearities and a huge number of degrees of freedom which are excited. Quantum mechanics introduces a great simplification into the problem, and constrains any rotational motion to discrete filaments of quantized circulation (in ordinary fluids vorticity is unconstrained). Despite this important difference, recent experiments in superfluid helium have revealed striking similarities with turbulence in ordinary fluids, notably the same distribution of kinetic energy over the lengthscales (the Kolmogorov energy spectrum). Perhaps "quantum turbulence" captures the essential nature of turbulence.

    Atomic condensates are an ideal context to study turbulence. Unlike helium, the fluid parameters can be tuned (including the strength and type of the interaction), individual vortices can be manipulated and imaged, and the dynamics can be modelled in a realistic way (using the Gross-Pitaevskii equation and its finite-temperature modifications). A unique property of atomic condensates is that the dimensionality can be modified through the external trapping potential, allowing the study of the transition from 3D to 2D (in the former, the energy transfer is from large scales to small scales, in the latter it is the other way around). Finally, the relative smallness of atomic condensates opens the problem of the transition from chaos to turbulence.

  2. Manipulating Light at Micro/Nano-Scale


    Micro/nano photonic structures permit remarkable control of the propagation of light. A selection of recent results will be presented.

    Using two-dimensional photonic crystal made of the composite materials with large and fast third-order optical nonlinearity, ultrafast and low threshold all-optical switching was demonstrated. Based on tunable Fano resonance or PIT of metallic nanostructures, ultrafast modulations on light transmission were also demonstrated. Moreover, ultracompact plasmonic devices including SPP unidirectional generator, splitter and others were experimentally demonstrated.

  3. Few Cycle High Intensity Lasers of and Related Developments in ELI-ALPS


    The Attosecond Light Pulse Source (ALPS) facility of the pan-European ELI project is designed to build a laser based research infrastructure in which light pulses of few optical cycles are generated and used for basic and applied research.

    Four laser systems under implementation deliver pulses with unique parameters: unparalleled fluxes, extreme broad bandwidths, and sub-cycle control of the generated fields. The high repetition rate (HR) system, delivers TW peak power, <5 fs pulses at 100 kHz. The 1-kHz repetition rate future single cycle (SYLOS) system provides 20 TW pulses with a pulse duration of <5 fs. The Petawatt-class high-field (HF) laser would operate at 10 Hz repetition rate with close to 15 fs pulse duration. The performance of the above laser systems operating with central wavelength in the range of 750–1030 nm is complemented by the mid-infrared (MIR) laser system, which provides sub-4 cycle, tunable laser pulses at 100 kHz repetition rate with over 15 W average power.

    In this talk the unique scientific and technical solutions of the laser sources are discussed, along with general infrastructure issues and research programs.

  4. Terahertz Photonics and Nonlinear Optics


    The recent years have been marked by the appearance of outstanding scientific achievements in THz photonics. These achievements have touched upon a range of areas of science, and each of them involved discovery of phenomena and applications whose appearance would be impossible in other electromagnetic radiation/emission range.

    In my lecture I will start with the historical development of ideas about this type of radiation. Its history dates back to the time when research of the nature of electromagnetic radiation was first undertaken. I will also tell you about the latest achievements in the development of laser sources for this frequency range. The increase in their power, coherence and expansion of frequency range allowed scientists to observe new coherent and nonlinear effects, start the development of plasmone optics of THz frequency range. Physics of THz metamaterials, biological and medical applications occupy a considerable place along with applications in chemistry and the study of materials. I will also tell you how to generate powerful THz radiation at large distances and in different gaseous media.

  5. Metrology and Light - in the Year of Light and Beyond


    Metrology with and for light has been an ever-increasing field since the invention of the dy-namo by W. V. Siemens in 1866 and of the carbon filament lamp by T. A. Edison in 1879. The foundation of the Physikalisch-Technische Reichsanstalt, PTR, in 1887 by H. V. Helmholtz and W. V. Siemens was among others strongly driven by the enormous growth of electric and lighting technologies in those days. Today we are facing a second revolution in light and lighting technologies with innovative laser-, LED- and OLED-source developments, the evolution of nano-photonics, single-photon and quantum-information technologies to name just a view with the quest for state-of-the-art metrology. In the future, light will play an even more important role for metrology with the advent of optical clocks, broad-band and high-precision optical fibre transmission technologies, methods to achieve spatial resolutions below the Abbe limit, with attosecond and free-electron-laser light sources coming online.

    In the talk the fascination of light for mankind, the development of light and lightening tech-nologies as well as present and future developments will be highlighted emphasizing in par-ticular the challenges and opportunities for metrology in the future.

  6. The 110 Years of the Photon. From Einstein’s Light Quanta to Extreme Light

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      Sándor Varró

      Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary
      Extreme Light Infrastructure - Attosecond Light Pulse Source (ELI-ALPS), ELI-Hu Nonprofit Ltd., Szeged, Hungary

    We review the historical background and variants of the notion of light quanta since Einstein’s “heuristic viewpoint” on the photoelectric effect was published in 1905. The conceptual development will be analysed, on the basis of discussing the interaction of extremely low-intensity and extremely large-intensity light with matter. At some points, we shall also attempt to interrelate the physical interpretations of the photon with light-related scientific measurement techniques and with the technological development.

  7. Ultrafast Processes of Molecules Induced by Intense Laser Fields


    If gas electron diffraction measurements are performed with a pulsed mode, we may be able probe the variations of geometrical structure of molecules in the gas phase with high precision. However, the temporal resolution that could be achieved by the pulsed gas electron diffraction method in which a pulsed electron beam is used could not be shorter than 1 ps. This 1-ps barrier could be broken by introducing a method called laser assisted electron scattering/diffraction, in which electrons are scattered by atoms or molecules under the presence of an ultrashort intense laser field. By the laser assisted diffraction method, we showed recently that instantaneous geometrical structure of polyatomic molecules can be determined [1].

    It has been known that geometrical structure of polyatomic molecules is deformed very rapidly in an ultrashort intense laser field. We found ultrafast hydrogen migration as well as slow hydrogen migration leading to the formation of H3+ proceed when hydrocarbon molecules are exposed to an intense laser field. By the coincidence momentum imaging method, we revealed the existence of ultrafast hydrogen migration and scrambling processes by mapping spatial positions of protons within a molecule [2]. In the case of the slow hydrogen migration process, it was shown from our recent studies [3] that a neutral hydrogen molecule can exist for a relatively long period of time so that it can vibrate and rotate within a dication parent molecule, and that a triatomic hydrogen molecular ion is ejected after the chemical bond rearrangement. We have learned that a group of hydrogen atoms in highly excited hydrocarbon molecules can exhibit rich dynamics in a multi-dimensional phase space in a variety of ways.

    1. [1] Y. Morimoto, R. Kanya, K. Yamanouchi, J. Chem. Phys. 140, 064201 (2014)
    2. [2] T. Okino, A. Watanabe, H. Xu, K. Yamanouchi, Phys. Chem. Chem. Phys. 14, 10640 (2012)
    3. [3] K. Nakai, T. Kato, H. Kono, K. Yamanouchi, J. Chem. Phys. 139, 181103 (2013)