@article{OPUS4-31269, title = {Measurement of prompt photon production in √ s(NN) = 8.16 TeV \(p\) Pb collisions with ATLAS}, series = {Physics letters B}, volume = {796}, journal = {Physics letters B}, organization = {The ATLAS Collaboration}, doi = {10.1016/j.physletb.2019.07.031}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312697}, pages = {230-252}, year = {2019}, abstract = {The inclusive production rates of isolated, prompt photons in p Pb collisions at root s(NN) = 8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb(-1) recorded in 2016. The cross-section and nuclear modification factor R-p pb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon-nucleon centre-of-mass pseudorapidity regions, (-2.83, -2.02), (-1.84, 0.91), and (1.09, 1.90). The cross-section and R-p pb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei. (C) 2019 The Author. Published by Elsevier B.V.}, language = {en} } @article{SoltamovKasperPoshakinskiyetal.2019, author = {Soltamov, V. A. and Kasper, C. and Poshakinskiy, A. V. and Anisimov, A. N. and Mokhov, E. N. and Sperlich, A. and Tarasenko, S. A. and Baranov, P. G. and Astakhov, G. V. and Dyakonov, V.}, title = {Excitation and coherent control of spin qudit modes in silicon carbide at room temperature}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-019-09429-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239149}, year = {2019}, abstract = {One of the challenges in the field of quantum sensing and information processing is to selectively address and coherently manipulate highly homogeneous qubits subject to external perturbations. Here, we present room-temperature coherent control of high-dimensional quantum bits, the so-called qudits, associated with vacancy-related spins in silicon carbide enriched with nuclear spin-free isotopes. In addition to the excitation of a spectrally narrow qudit mode at the pump frequency, several other modes are excited in the electron spin resonance spectra whose relative positions depend on the external magnetic field. We develop a theory of multipole spin dynamics and demonstrate selective quantum control of homogeneous spin packets with sub-MHz spectral resolution. Furthermore, we perform two-frequency Ramsey interferometry to demonstrate absolute dc magnetometry, which is immune to thermal noise and strain inhomogeneity.}, language = {en} } @article{SchmittMorasBihlmayeretal.2019, author = {Schmitt, Martin and Moras, Paolo and Bihlmayer, Gustav and Cotsakis, Ryan and Vogt, Matthias and Kemmer, Jeannette and Belabbes, Abderrezak and Sheverdyaeva, Polina M. and Kundu, Asish K. and Carbone, Carlo and Bl{\"u}gel, Stefan and Bode, Matthias}, title = {Indirect chiral magnetic exchange through Dzyaloshinskii-Moriya-enhanced RKKY interactions in manganese oxide chains on Ir(100)}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-019-10515-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230986}, year = {2019}, abstract = {Localized electron spins can couple magnetically via the Ruderman-Kittel-Kasuya-Yosida interaction even if their wave functions lack direct overlap. Theory predicts that spin-orbit scattering leads to a Dzyaloshinskii-Moriya type enhancement of this indirect exchange interaction, giving rise to chiral exchange terms. Here we present a combined spin-polarized scanning tunneling microscopy, angle-resolved photoemission, and density functional theory study of MnO2 chains on Ir(100). Whereas we find antiferromagnetic Mn-Mn coupling along the chain, the inter-chain coupling across the non-magnetic Ir substrate turns out to be chiral with a 120° rotation between adjacent MnO2 chains. Calculations reveal that the Dzyaloshinskii-Moriya interaction results in spin spirals with a periodicity in agreement with experiment. Our findings confirm the existence of indirect chiral magnetic exchange, potentially giving rise to exotic phenomena, such as chiral spin-liquid states in spin ice systems or the emergence of new quasiparticles.}, language = {en} } @article{KremerBiesenthalMaczewskyetal.2019, author = {Kremer, Mark and Biesenthal, Tobias and Maczewsky, Lukas J. and Heinrich, Matthias and Thomale, Ronny and Szameit, Alexander}, title = {Demonstration of a two-dimensional PT-symmetric crystal}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-018-08104-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230132}, year = {2019}, abstract = {With the discovery of PT-symmetric quantum mechanics, it was shown that even non-Hermitian systems may exhibit entirely real eigenvalue spectra. This finding did not only change the perception of quantum mechanics itself, it also significantly influenced the field of photonics. By appropriately designing one-dimensional distributions of gain and loss, it was possible to experimentally verify some of the hallmark features of PT-symmetry using electromagnetic waves. Nevertheless, an experimental platform to study the impact of PT-symmetry in two spatial dimensions has so far remained elusive. We break new grounds by devising a two-dimensional PT-symmetric system based on photonic waveguide lattices with judiciously designed refractive index landscape and alternating loss. With this system at hand, we demonstrate a non-Hermitian two-dimensional topological phase transition that is closely linked to the emergence of topological mid-gap edge states.}, language = {en} } @article{KreinbergPorteSchickeetal.2019, author = {Kreinberg, S{\"o}ren and Porte, Xavier and Schicke, David and Lingnau, Benjamin and Schneider, Christian and H{\"o}fling, Sven and Kanter, Ido and L{\"u}dge, Kathy and Reitzenstein, Stephan}, title = {Mutual coupling and synchronization of optically coupled quantum-dot micropillar lasers at ultra-low light levels}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-019-09559-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229811}, year = {2019}, abstract = {Synchronization of coupled oscillators at the transition between classical physics and quantum physics has become an emerging research topic at the crossroads of nonlinear dynamics and nanophotonics. We study this unexplored field by using quantum dot microlasers as optical oscillators. Operating in the regime of cavity quantum electrodynamics (cQED) with an intracavity photon number on the order of 10 and output powers in the 100 nW range, these devices have high β-factors associated with enhanced spontaneous emission noise. We identify synchronization of mutually coupled microlasers via frequency locking associated with a sub-gigahertz locking range. A theoretical analysis of the coupling behavior reveals striking differences from optical synchronization in the classical domain with negligible spontaneous emission noise. Beyond that, additional self-feedback leads to zero-lag synchronization of coupled microlasers at ultra-low light levels. Our work has high potential to pave the way for future experiments in the quantum regime of synchronization.}, language = {en} } @article{IzquierdoKarolakPrabhakaranetal.2019, author = {Izquierdo, Manuel and Karolak, Michael and Prabhakaran, Dharmalingam and Boothroyd, Andrew T. and Scherz, Andreas O. and Lichtenstein, Alexander and Molodtsov, Serguei L.}, title = {Monitoring ultrafast metallization in LaCoO3 with femtosecond soft x-ray spectroscopy}, series = {Communications Physics}, volume = {2}, journal = {Communications Physics}, doi = {10.1038/s42005-019-0109-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-323265}, year = {2019}, abstract = {The study of ultrafast dynamics is a new tool to understand and control the properties of correlated oxides. By enhancing some properties and realizing new dynamically excited phrases, this tool has opened new routes for technological applications. LaCoO3 is one paradigmatic example where the strong electron, spin, and lattice coupling induced by electronic correlations results in a low-temperature spin transition and a high-temperature semiconductor-to-metal transition that is still not completely understood. Here, we monitor ultrafast metallization in LaCoO3 using time-resolved soft x-ray reflectivity experiments. While the process is entangled at the Co L3 edge, the time information of the different channels is decrypted at different resonant energies of the O K edge. Metallization is shown to occur via transient electronic, spin, and lattice separation. Our results agree with the thermodynamical model and demonstrate the potential of femtosecond soft x-ray experiments at the O K edge to understand correlated oxides.}, language = {en} } @article{HolzingerSchneiderHoeflingetal.2019, author = {Holzinger, Steffen and Schneider, Christian and H{\"o}fling, Sven and Porte, Xavier and Reitzenstein, Stephan}, title = {Quantum-dot micropillar lasers subject to coherent time-delayed optical feedback from a short external cavity}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-018-36599-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-322485}, year = {2019}, abstract = {We investigate the mode-switching dynamics of an electrically driven bimodal quantum-dot micropillar laser when subject to delayed coherent optical feedback from a short external cavity. We experimentally characterize how the external cavity length, being on the same order than the microlaser's coherence length, influences the spectral and dynamical properties of the micropillar laser. Moreover, we determine the relaxation oscillation frequency of the micropillar by superimposing optical pulse injection to a dc current. It is found that the optical pulse can be used to disturb the feedback-coupled laser within one roundtrip time in such a way that it reaches the same output power as if no feedback was present. Our results do not only expand the understanding of microlasers when subject to optical feedback from short external cavities, but pave the way towards tailoring the properties of this key nanophotonic system for studies in the quantum regime of self-feedback and its implementation to integrated photonic circuits.}, language = {en} } @article{OPUS4-36018, title = {Search for Multimessenger Sources of Gravitational Waves and High-energy Neutrinos with Advanced LIGO during Its First Observing Run, ANTARES, and IceCube}, series = {The Astrophysical Journal}, volume = {870}, journal = {The Astrophysical Journal}, number = {2}, publisher = {The American Astronomical Society}, organization = {The LIGO Scientific Collaboration and the Virgo Collaboration}, doi = {10.3847/1538-4357/aaf21d}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-360189}, pages = {1-16}, year = {2019}, abstract = {Astrophysical sources of gravitational waves, such as binary neutron star and black hole mergers or core-collapse supernovae, can drive relativistic outflows, giving rise to non-thermal high-energy emission. High-energy neutrinos are signatures of such outflows. The detection of gravitational waves and high-energy neutrinos from common sources could help establish the connection between the dynamics of the progenitor and the properties of the outflow. We searched for associated emission of gravitational waves and high-energy neutrinos from astrophysical transients with minimal assumptions using data from Advanced LIGO from its first observing run O1, and data from the Antares and IceCube neutrino observatories from the same time period. We focused on candidate events whose astrophysical origins could not be determined from a single messenger. We found no significant coincident candidate, which we used to constrain the rate density of astrophysical sources dependent on their gravitational-wave and neutrino emission processes.}, language = {en} } @article{OPUS4-22694, title = {FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2}, series = {European Physical Journal - Special Topics}, volume = {228}, journal = {European Physical Journal - Special Topics}, number = {2}, organization = {The FCC Collaboration}, doi = {10.1140/epjst/e2019-900045-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226947}, pages = {261-623}, year = {2019}, abstract = {In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today's technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics.}, language = {en} } @article{OPUS4-22693, title = {FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1}, series = {European Physical Journal C}, volume = {79}, journal = {European Physical Journal C}, number = {474}, organization = {The FCC Collaboration}, doi = {10.1140/epjc/s10052-019-6904-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226938}, pages = {1-161}, year = {2019}, abstract = {We review the physics opportunities of the Future Circular Collider, covering its e(+)e(-), pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics.}, language = {en} }