Newsletter April 2015
Laser photon merging in an electromagnetic field inhomogeneity
We study the effect of laser photon merging, or equivalently high harmonic generation, in the quantum vacuum subject to inhomogeneous electromagnetic fields. Such a process is facilitated by the effective nonlinear couplings arising from charged particle-antiparticle fluctuations in the quantum vacuum in strong electromagnetic fields. We derive explicit results for general kinematic and polarization configurations involving optical photons. Concentrating on merged photons in reflected channels which are preferable in experiments for reasons of noise suppression, we demonstrate that photon merging is typically dominated by the competing nonlinear process of quantum reflection, though appropriate polarization and signal filtering could specifically search for the merging process. As a byproduct, we devise a novel systematic expansion of the photon polarization tensor in plane wave fields.
The discovery of quantum vacuum nonlinearities  under controlled laboratory conditions using real photons or macroscopic electromagnetic fields is a major goal of contemporary strong-field physics. Many proposals rely on a pump-probe scheme, where a well-controlled, say optical, photon beam probes a region of space that is exposed to a strong field (``pump''). A typical example is given by schemes intended to verify vacuum birefringence that can be searched for using macroscopic magnetic fields or with the aid of high-intensity lasers.
The pump-probe scheme is typically also reflected by the theoretical description, in which the nonlinearities are kept for the pump-probe interaction, but the equations are linearized with respect to the probe propagation. In the present work, we rely again on an optical pump-probe setup which however requires a nonlinear treatment of the probe-field. The idea is to look for laser photon merging in the presence of an electromagnetic field inhomogeneity. This effect resembles the standard nonlinear optical process of second armonic generation (SHG) - or in general high harmonic generation - with the nonlinear crystal replaced by the quantum vacuum subject to strong electromagnetic fields.
Laser photon merging in proton-laser collisions have been investigated in detail in , where a promising scenario has been proposed for a discovery of the merging phenomenon that involves a nowadays conventional optical high-intensity laser at a high-energy proton collider. In the present work , we concentrate on an ``all-optical'' parameter regime realizable with high-intensity lasers. As the signal is expected to be very small, we consider specifically the kinematics of the reflection process for an appropriate signal-to-noise reduction. We limit ourselves to the study of time-independent field inhomogeneities, such that there is no energy transfer from the field inhomogeneity. Depending on the spatial field inhomogeneity, the propagation direction of the merged photons can differ from that of the incident probe photons. For the specific reflecting kinematic situation, the merged photons can even propagate - somewhat counter-intuitively - into the backward direction. For a straightforward comparison of the signals resulting from quantum reflection  and the photon merging scenario of this work, we focus on a one-dimensional magnetic field inhomogeneity. Our findings confirm the expectation that the merging process for the reflective scenario is dominated by the quantum reflection process for the all-optical parameter regime. Nevertheless, due to a different polarization and frequency dependence, filtering techniques might allow for a discovery of the merging process in this set up as well.
 W. Heisenberg and H. Euler, Z. Phys. 98, 71 (1936).
 A.Di Piazza, K. Z. Hatsagortsyan and C. H. Keitel, PRL 100, 010403 (2008) and PRA 78, 062109 (2008).
 H. Gies, F. Karbstein and R. Shaisultanov, PRD 90, 033007 (2014).
 H. Gies, F. Karbstein and N. Seegert, NJP 15, 083002 (2013).
Guests of the institute
It is a great pleasure to announce a guest scientist of the HI Jena:
Professor Valeriy G. Serbo (Novosibirsk State University, Russia) is visiting the HI Jena for two months (April 15th to June 15th, 2015).
Seminar room HI-Jena, Fröbelstieg 3
Due to the presence of zero-point energy fluctuations, the matter-free quantum vacuum acquires properties akin to those of a nonlinear medium. We theoretically investigate the interaction of photons with inhomogeneous electromagnetic background fields in vacuum, namely quantum reflection and photon merging, with emphasis on a possible experimental verification employing high-intensity lasers.
9th International Symposium on Swift Heavy Ions in Matter
SHIM 2015 will be the 9th International Symposium in a series which was started in Caen (France) in 1989. The conference brings together scientists performing research with high-energy heavy ions in various fields, including radiation effects in solids, atomic physics, plasma physics, radiation biology and medicine, as well as nanotechnology. SHIM focuses on basic as well as applied research, including both theoretical and experimental aspects.
The sessions will comprise invited lectures as well as oral and poster presentations. There will be no parallel sessions. Proceedings are planned as special issue of Nuclear Instruments and Methods B. The conference will take place in the "darmstadtium" convention Center located in the heart of Darmstadt.
SHIM 2015 will consist of 3 1/2 days of conference, starting at 9:00 am on Monday, May 18, and ending early afternoon on Thursday, May 21. The welcome reception will be on Sunday evening, May 17.
39th International conference on Vacuum Ultraviolet and X-ray Physics, VUVX2016
Further information will be available the second half of 2015. For further updated information you can anytime consult the conference web site: http://www.psi.ch/vuvx2016
European Summer School 2015: LIGHT! An introduction to modern Physics of Light
We would like to draw your attention to this year's European Summer School, which is part of the International Year of Light and its applications: LIGHT ! An introduction to modern Physics of Light
The school is open to students in physics who have completed three years of studies and to young PhD students.
The European Summer School of the University of Strasbourg is a prestigious one-week meeting of students from all over Europe. Students present their research projects and attend lectures on one of the most recent topics in physics presented by internationally known scientists. The 2015 Summer School will be dedicated to the physics of Light, and will offer an enthusiastic and educational introduction to some of the most recent research areas in this field.
The European Summer School will be open for applications at least until May 17, 2015:
Conference web page: http://esc.u-strasbg.fr/
4th International FAIR School
Castiglione della Pescaia, Italy
The 4th International FAIR School, will take place in September in Castiglione della Pescaia in Italy. It is designed for young students with research interests in FAIR physics and is a good start to get an overview on what's happening at FAIR.
Local costs are covered, there is limited support for travel as well. The selection of students will be made early June, the deadline for application is May 31.
More information can be found at: https://hgs-hire.de/program/events/fair-school-2015/index.shtml
Extreme-field physics in Penning traps
M. Vogel, G. Birkl, M. Ebrahimi, D. von Lindenfels, A. Martin, G. Paulus, W. Quint, S. Ringleb, Th. Stöhlker, and M. Wiesel
Hyperfine Interact. 236, 65 (2015)
Narrowband inverse Compton scattering x-ray sources at high laser intensities
D. Seipt, S. G. Rykovanov, A. Surzhykov, and S. Fritzsche
Phys. Rev. A 91, 033402 (2015)
Total projectile electron loss cross sections of U²⁸⁺ ions in collisions with gaseous targets ranging from hydrogen to krypton
G. Weber, M. Herdrich, R. DuBois, P.-M. Hillenbrand, H. Beyer, L. Bozyk, T. Gassner, R. Grisenti, S. Hagmann, Y. Litvinov, F. Nolden, N. Petridis, M. Sanjari, D. Winters, and Th. Stöhlker
Phys. Rev. ST Accel. Beams 18, 034403 (2015)
Effect of hydroxyl concentration on Yb3+ luminescence properties in a peraluminous lithium-alumino-silicate glass
S. Kuhn, M. Tiegel, A. Herrmann, J. Körner, R. Seifert, F. Yue, D. Klöpfel, J. Hein, M. C. Kaluza, and C. Rüssel
Opt. Mater. Express 5, 430 (2015)
Electron-capture-to-continuum cusp in U⁸⁸⁺+N₂ collisions
P.-M. Hillenbrand, S. Hagmann, D. H. Jakubassa-Amundsen, J. M. Monti, D. Banaś, K.-H. Blumenhagen, C. Brandau, W. Chen, P. D. Fainstein, E. De Filippo, A. Gumberidze, D. L. Guo, M. Lestinsky, Yu. A. Litvinov, A. Müller, R. D. Rivarola, H. Rothard, S. Schippers, M. S. Schöffler, U. Spillmann, S. Trotsenko, X. L. Zhu, and Th. Stöhlker
Phys. Rev. A 91, 022705 (2015)
Multi-element readout of structured HPGe-detectors for high-resolution x-ray spectroscopy using CUBE-preamplifiers
T. Krings, U. Spillmann, D. Protić, C. Roß, Th. Stöhlker, G. Weber, L. Bombelli, R. Alberti, and T. Frizzi
J. Instrum. 10, C02043 (2015)
Multidimensional coherent pulse addition of ultrashort laser pulses
M. Kienel, M. Müller, A. Klenke, T. Eidam, J. Limpert, and A. Tünnermann
Opt. Lett. 40, 522 (2015)
A novel double hohlraum target to create a moderately coupled plasma for ion stopping experiments
A. Ortner, S. Faik, D. Schumacher, M. Basko, A. Blazevic, S. Busold, S. Bedacht, W. Cayzac, A. Frank, D. Kraus, T. Rienecker, G. Schaumann, An. Tauschwitz, F. Wagner, and M. Roth
Nucl. Instr. Meth. Phys. Res. B 343, 123 (2015)
Characterization of laser-driven proton beams from near-critical density targets using copper activation
L. Willingale, S. Nagel, A. Thomas, C. Bellei, R. Clarke, A. Dangor, R. Heathcote, M. Kaluza, C. Kamperidis, S. Kneip, K. Krushelnick, N. Lopes, S. P. D. Mangles, W. Nazarov, P. M. Nilson, and Z. Najmudin
J. Plasma Phys. 81, 365810102 (2015)
Electron-ion collision spectroscopy: Lithium-like xenon ions
D. Bernhardt, C. Brandau, Z. Harman, C. Kozhuharov, S. Böhm, F. Bosch, S. Fritzsche, J. Jacobi, S. Kieslich, H. Knopp, F. Nolden, W. Shi, Z. Stachura, M. Steck, Th. Stöhlker, S. Schippers, and A. Müller
Phys. Rev. A 91, 012710 (2015)
Laser-driven ion acceleration with hollow laser beams
C. Brabetz, S. Busold, T. Cowan, O. Deppert, D. Jahn, O. Kester, M. Roth, D. Schumacher, and V. Bagnoud
Phys. Plasmas 22, 013105 (2015)
Bright Subcycle Extreme Ultraviolet Bursts from a Single Dense Relativistic Electron Sheet
W. Ma, J. Bin, H. Wang, M. Yeung, C. Kreuzer, M. Streeter, P. Foster, S. Cousens, D. Kiefer, B. Dromey, X. Yan, J. Meyer-ter-Vehn, M. Zepf, and J. Schreiber
Phys. Rev. Lett. 113, 235002 (2014)
Electrons take the fast track through silicon
Science 346, 1293 (2014)
Pre-plasma formation in experiments using petawatt lasers
F. Wagner, S. Bedacht, A. Ortner, M. Roth, A. Tauschwitz, B. Zielbauer, and V. Bagnoud
Opt. Express 22, 29505 (2014)
Relativistic calculations of double K-shell-photoionization cross sections for neutral medium-Z atoms
V. A. Yerokhin, A. Surzhykov, and S. Fritzsche
Phys. Rev. A 90, 063422 (2014)
2 kW average power from a pulsed Yb-doped rod-type fiber amplifier
H.-J. Otto, F. Stutzki, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann
Opt. Lett. 39, 6446 (2014)
Diagnostics for studies of novel laser ion acceleration mechanisms
L. Senje, M. Yeung, B. Aurand, S. Kuschel, C. Rödel, F. Wagner, K. Li, B. Dromey, V. Bagnoud, P. Neumayer, M. Roth, C.-G. Wahlström, M. Zepf, T. Kuehl, and D. Jung
Rev. Sci. Instrum. 85, 113302 (2014)
Image plate characterization and absolute calibration to low kilo-electron-volt electrons
S. Busold, K. Philipp, A. Otten, and M. Roth
Rev. Sci. Instrum. 85, 113306 (2014)
Quasi-monoenergetic femtosecond photon sources from Thomson Scattering using laser plasma accelerators and plasma channels
S. G. Rykovanov, C. G. R. Geddes, J.-L. Vay, C. B. Schroeder, E. Esarey, and W. P. Leemans
J. Phys. B 47, 234013 (2014)
Surfen auf der Plasmawelle
Phys. Unserer Zeit 45, 274 (2014)
Ultrahigh Brilliance Multi-MeV γ-Ray Beams from Nonlinear Relativistic Thomson Scattering
G. Sarri, D. Corvan, W. Schumaker, J. Cole, A. Di Piazza, H. Ahmed, C. Harvey, C. Keitel, K. Krushelnick, S. Mangles, Z. Najmudin, D. Symes, A. Thomas, M. Yeung, Z. Zhao, and M. Zepf
Phys. Rev. Lett. 113, 224801 (2014)
Low-energy electron rescattering in laser-induced ionization
W. Becker, S. P. Goreslavski, D. B. Milošević, and G. G. Paulus
J. Phys. B 47, 204022 (2014)