Peer-Review Publications


Lars Lötgering, Mengqi Du, Dirk Boonzajer Flaes, Tomas Aidukas, Felix Wechsler, Daniel Santiago Penagos Molina, Max Rose, Antonios Pelekanidis, Wilhelm Eschen, Jürgen Hess, Thomas Wilhein, Rainer Heintzmann, Jan Rothhardt, and Stefan Witte
PtyLab.m/py/jl: a cross-platform, open-source inverse modeling toolbox for conventional and Fourier ptychography
Optics express, 31 (9) :13763 ( 2023)
Publisher: OSA
ISSN: 1094-4087
Danish Furekh Dar, and Stephan Fritzsche
Pulse Cycle Dependent Nondipole Effects in Above-Threshold Ionization
Atoms, 11 (6) :97 ( 2023)
Publisher: MDPI
ISSN: 2218-2004
Henning Stark, Maximilian Benner, Joachim Buldt, Arno Klenke, and Jens Limpert
Pulses of 32 mJ and 158 fs at 20-kHz repetition rate from a spatiotemporally combined fiber laser system
Optics letters, 48 (11) :3007 ( 2023)
Publisher: OSA
ISSN: 0146-9592
Anna Maiorova, Stephan Fritzsche, Andrey Surzhykov, and Thomas Stöhlker
Radiative recombination of highly charged ions with polarized electrons
Physical review / A, 107 (4) :042814 ( 2023)
Publisher: APS
ISSN: 2469-9926
Stephan Fritzsche, Anna Maiorova, and Zhongwen Wu
Radiative Recombination Plasma Rate Coefficients for Multiply Charged Ions
Atoms, 11 (3) :50 ( 2023)
Publisher: MDPI
ISSN: 2218-2004
Binghui Zhu, and Thomas Stöhlker
Radiative Recombination Studies for Bare Lead Ions Interacting with Low-Energy Electrons
Atoms, 11 (1) :2 ( 2023)
Publisher: MDPI
ISSN: 2218-2004
C. Zepter, A. Seidel, M. Zepf, M. C. Kaluza, and A. Sävert
Role of spatiotemporal couplings in stimulated Raman side scattering
Physical review research, 5 (1) :L012023 ( 2023)
Publisher: APS
ISSN: 2643-1564
Guang Yang, Vinicius Silva Oliveira, Dominic Laumer, Christoph M. Heyl, Andrey Yachmenev, Ingmar Hartl, and Jochen Küpper
Self-broadening and self-shift in the $3v_2$ band of ammonia from mid-infrared-frequency-comb spectroscopy
Journal of molecular spectroscopy, 392 :111744 ( 2023)
Publisher: Academic Press
ISSN: 0022-2852
Richard Bernecker, Baghdasar Baghdasaryan, and Stephan Fritzsche
Spatial and temporal characteristics of spontaneous parametric down-conversion with varying focal planes of interacting beams
The European physical journal / D, 77 (9) :172 ( 2023)
Publisher: Springer
ISSN: 1434-6060
Elias Kueny, Anne-Laure Calendron, Sven Velten, Lars Bocklage, Franz X. Kärtner, and Ralf Röhlsberger
Spin-structured multilayer THz emitters by oblique incidence deposition
Journal of applied physics, 133 (3) :033903 ( 2023)
Publisher: American Inst. of Physics
ISSN: 0021-8979
Ruo Yu Zheng, Li Guang Jiao, Aihua Liu, Jia Ma, Henry E Montgomery Jr, Yew Kam Ho, and Stephan Fritzsche
Stability of the $2p^2$ $^3P^e$ state of two-electron atoms near to critical nuclear charge
Journal of physics / B, 56 (9) :095002 ( 2023)
Publisher: IOP Publ.
ISSN: 0022-3700
S. Kosugi, F. Koike, M. Iizawa, F. Hosseini, J. Martins, T. Marchenko, O. Travnikova, J. D. Bozek, K. Ito, Stephan Fritzsche, M. N. Piancastelli, M. Simon, and Y. Azuma
Strong configuration-interaction contributions to the angle-resolved $4_p$ photoelectron spectra of atomic xenon
Physical review / A, 107 (2) :022814 ( 2023)
Publisher: APS
ISSN: 2469-9926
Dominic Laumer, Haydar Sarper Salman, Yuxuan Ma, Kevin T. Zawilski, Peter G. Schunemann, Marcus Seidel, Christoph Heyl, and Ingmar Hartl
Sub-Hz relative linewidths from an interferometrically stabilized mid-infrared frequency comb
Optics letters, 48 (11) :3055 ( 2023)
Publisher: OSA
ISSN: 0146-9592
Kristian König, Stephan Fritzsche, Gaute Hagen, Jason D. Holt, Andrew Klose, Jeremy Lantis, Yuan Liu, Kei Minamisono, Takayuki Miyagi, Witold Nazarewicz, Thomas Papenbrock, Skyy V. Pineda, Robert Powel, and Paul-Gerhard Reinhard
Surprising Charge-Radius Kink in the Sc Isotopes at N = 20
Physical review letters, 131 (10) :102501 ( 2023)
Publisher: APS
ISSN: 0031-9007
F. Kröger, G. Weber, S. Allgeier, Z. Andelkovic, S. Bernitt, A. Borovik, L. Duval, A. Fleischmann, O. Forstner, M. Friedrich, J. Glorius, A. Gumberidze, C. Hahn, F. Herfurth, D. Hengstler, M. Herdrich, P.-M. Hillenbrand, A. Kalinin, M. Kiffer, M. Kubullek, P. Kuntz, M. Lestinsky, B. Löher, E. Menz, T. Over, N. Petridis, P. Pfäfflein, S. Ringleb, R. Sidhu, U. Spillmann, S. Trotsenko, A. Warczak, B. Zhu, C. Enss, and T. Stöhlker
Towards an Intrinsic Doppler Correction for X-ray Spectroscopy of Stored Ions at CRYRING@ESR
Atoms, 11 :1 (January 2023)
We report on a new experimental approach for the Doppler correction of X-rays emitted by heavy ions, using novel metallic magnetic calorimeter detectors which uniquely combine a high spectral resolution with a broad bandwidth acceptance. The measurement was carried out at the electron cooler of CRYRING@ESR at GSI, Darmstadt, Germany. The X-ray emission associated with the radiative recombination of cooler electrons and stored hydrogen-like uranium ions was investigated using two novel microcalorimeter detectors positioned under 0∘ and 180∘ with respect to the ion beam axis. This new experimental setup allowed the investigation of the region of the N, M → L transitions in helium-like uranium with a spectral resolution unmatched by previous studies using conventional semiconductor X-ray detectors. When assuming that the rest-frame energy of at least a few of the recorded transitions is well-known from theory or experiments, a precise measurement of the Doppler shifted line positions in the laboratory system can be used to determine the ion beam velocity using only spectral information. The spectral resolution achievable with microcalorimeter detectors should, for the first time, allow intrinsic Doppler correction to be performed for the precision X-ray spectroscopy of stored heavy ions. A comparison with data from a previous experiment at the ESR electron cooler, as well as the conventional method of conducting Doppler correction using electron cooler parameters, will be discussed.
H. N. Gopalakrishna, R. Baruah, C. Hünecke, V. Korolev, M. Thümmler, A. Croy, M. Richter, F. Yahyaei, R. Hollinger, V. Shumakova, I. Uschmann, H. Marschner, M. Zürch, C. Reichardt, A. Undisz, J. Dellith, A. Pugžlys, A. Baltuska, C. Spielmann, U. Peschel, S. Gräfe, M. Wächtler, and D. Kartashov
Tracing spatial confinement in semiconductor quantum dots by high-order harmonic generation
Physical review research, 5 (1) :013128 ( 2023)
Publisher: APS
ISSN: 2643-1564
P. Balla, H. Tuennermann, S. Salman, M. Fan, S. Ališauskas, I. Hartl, and C. Heyl
Ultrafast serrodyne optical frequency translator
Nature Photonics, 17 :187 (December 2023)
The serrodyne principle enables an electromagnetic signal to be frequency shifted by applying a linear phase ramp in the time domain. This phenomenon has been exploited to frequency shift signals in the radiofrequency, microwave and optical regions of the electromagnetic spectrum over ranges of up to a few gigahertz, for example, to analyse the Doppler shift of radiofrequency signals for noise suppression and frequency stabilization. Here we employ this principle to shift the centre frequency of high-power femtosecond laser pulses over a range of several terahertz with the help of a nonlinear multi-pass cell. We demonstrate our method experimentally by shifting the central wavelength of a state-of-the-art 75 W frequency comb laser from 1,030 nm to 1,060 nm and to 1,000 nm. Furthermore, we experimentally show that this wavelength-shifting technique supports coherence characteristics at the few hertz-level while improving the temporal pulse quality. The technique is generally applicable to wide parameter ranges and different laser systems, enabling efficient wavelength conversion of high-power lasers to spectral regions beyond the gain bandwidth of available laser platforms.
Malte Christoph Kaluza
Unveiling the inner structure of electron pulses generated from a laser-wakefield accelerator
Light, 12 (1) :225 ( 2023)
Publisher: Nature Publishing Group
ISSN: 2047-7538
Wen Hao Xia, Zhi Ling Zhou, Li Guang Jiao, Aihua Liu, Henry E. Montgomery, Yew Kam Ho, and Stephan Fritzsche
Variational perturbation theory for dynamic polarizabilities and dispersion coefficients
Physical review / E, 108 (3) :035305 ( 2023)
Publisher: APS
ISSN: 2470-0045
Yannik Zobus, Christian Brabetz, Markus Loeser, Daniel Albach, Mathias Siebold, and Vincent Bagnoud
Versatile, compact chirped pulse amplifier pump system for ultrafast optical parametric amplifiers
Optics express, 31 (3) :5002 - (January 2023)
Publisher: Optica
ISSN: 1094-4087
C. Liu, W. Eschen, L. Loetgering, D. Molina, R. Klas, A. Iliou, M. Steinert, S. Herkersdorf, A. Kirsche, T. Pertsch, F. Hillmann, J. Limpert, and J. Rothhardt
Visualizing the ultra-structure of microorganisms using table-top extreme ultraviolet imaging
PhotoniX, 4 :1 (January 2023)
Table-top extreme ultraviolet (EUV) microscopy offers unique opportunities for label-free investigation of biological samples. Here, we demonstrate ptychographic EUV imaging of two dried, unstained model specimens: germlings of a fungus (Aspergillus nidulans), and bacteria (Escherichia coli) cells at 13.5 nm wavelength. We find that the EUV spectral region, which to date has not received much attention for biological imaging, offers sufficient penetration depths for the identification of intracellular features. By implementing a position-correlated ptychography approach, we demonstrate a millimeter-squared field of view enabled by infrared illumination combined with sub-60 nm spatial resolution achieved with EUV illumination on selected regions of interest. The strong element contrast at 13.5 nm wavelength enables the identification of the nanoscale material composition inside the specimens. Our work will advance and facilitate EUV imaging applications and enable further possibilities in life science.
M. Herdrich, D. Hengstler, A. Fleischmann, C. Enss, A. Gumberidze, P.-M. Hillenbrand, P. Indelicato, S. Fritzsche, and T. Stöhlker
X-ray Spectroscopy Based on Micro-Calorimeters at Internal Targets of Storage Rings
Atoms, 11 :1 (January 2023)
With metallic-magnetic calorimeters (MMCs), promising detectors for high-precision X-ray spectrometry in atomic and fundamental physics experiments are available. In this work, we present a pilot experiment based on a maXs-30 type MMC-spectrometer for recording X-rays emitted in collisions of lithium-like uranium ions with a molecular nitrogen gas jet in the internal target of the ESR storage ring of the GSI. Sample spectra have been measured, and a multitude of X-ray transitions have been unambiguously identified. As a first test and for comparison with data recorded at an EBIT, the 2s Lamb shift in lithium-like uranium was estimated.


B. Liu, M. Shi, M. Zepf, B. Lei, and D. Seipt
Accelerating Ions by Crossing Two Ultraintense Lasers in a Near-Critical Relativistically Transparent Plasma
Phys. Rev. Lett., 129 :274801 (December 2022)
A new scheme of ion acceleration by crossing two ultraintense laser pulses in a near-critical relativistically transparent plasma is proposed. One laser, acting as a trigger, preaccelerates background ions in its radial direction via the laser-driven shock. Another crossed laser drives a comoving snowplow field which traps some of the preaccelerated ions and then efficiently accelerates them to high energies up to a few giga-electron-volts. The final output ion beam is collimated and quasimonoenergetic due to a momentum-selection mechanism. Particle-in-cell simulations and theoretical analysis show that the scheme is feasible and robust.
H. Gies, F. Karbstein, and L. Klar
All-optical quantum vacuum signals in two-beam collisions
Phys. Rev. D, 106 :116005 (December 2022)
We study the collision of two optical laser pulses in a pump-probe setup using beams with circular and elliptic cross section and estimate the number of discernible signal photons induced by quantum vacuum nonlinearities. In this analysis we study strategies to optimize the quantum vacuum signal discernible from the background of the driving lasers. One of the main results is that the collision of two maximally focused lasers does not lead to the best discernible signal. Instead, widening the focus typically improves the signal to background separation in the far field. For petawatt class lasers, an optimal choice of the focus waist yields several discernible photons per shot in contrast to no discernible signal for tight focusing. Further enhancement is possible by using an elliptical waist.
S. Fritzsche
Application of Symmetry-Adapted Atomic Amplitudes
Atoms, 10 :127 (December 2022)
Following the work of Giulio Racah and others from the 1940s onward, the rotational symmetry of atoms and ions, e.g., the conservation of angular momentum, has been utilized in order to efficiently predict atomic behavior, from their level structure to the interaction with external fields, and up to the angular distribution and polarization of either emitted or scattered photons and electrons, while this rotational symmetry becomes apparent first of all in the block-diagonal structure of the Hamiltonian matrix, it also suggests a straight and consequent use of symmetry-adapted interaction amplitudes in expressing the observables of most atomic properties and processes. We here emphasize and discuss how atomic structure theory benefits from exploiting this symmetry, especially if open-shell atoms and ions in different charge states need to be combined with electrons in the continuum. By making use of symmetry-adapted amplitudes, a large number of excitation, ionization, recombination or even cascade processes can be formulated rather independently of the atomic shell structure and in a language close to the formal theory. The consequent use of these amplitudes in existing codes such as Grasp will therefore qualify them to deal with the recently emerging demands for developing general-purpose tools for atomic computations.