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Item Nonlinear excitation of energetic particle driven geodesic acoustic mode by resonance overlap with Alfvén instability in ASDEX Upgrade(Nature Research, 2025) Wang, Hao; Lauber, Philipp; Todo, Yasushi; Suzuki, Yasuhiro; Li, Hanzheng; Idouakass, Malik; Wang, Jialei; Adulsiriswad, Panith; Zoletnik, S.; Zohm, H.; Zito, A.; Zimmermann, C.F.B.; Zilker, M.; Zibrov, A.; Zholobenko, W.; Zhang, W.; Zehetbauer, T.; Zammuto, I.; Zagórski, R.; Yu, Q.; Yoo, C.; Yang, Q.; Wolfrum, E.; Wolf, R.; Wischmeier, M.; Wiringer, B.; Willensdorfer, M.; White, A.E.; Wendler, D.; Weiland, M.; Wang, X.; Wagner, D.; von Toussaint, U.; Voitsekhovitch, I.; Viezzer, E.; Vierle, T.; Vicente, J.; Vianello, N.; Verdoolaege, G.; Verdier, T.; Varoutis, S.; Varela, P.; Vanovac, B.; Vannini, F.; van Zeeland, M.; van Mulders, S.; Valovic, M.; Valisa, M.; Usoltseva, M.; Urbanczyk, G.; Ulbl, P.; Tripský, M.; Trevisan, G.; Treutterer, W.; Told, D.; Tierens, W.; Thorén, E.; Teschke, M.; Terranova, D.; Tardocchi, M.; Tardini, G.; Tang, W.; Tala, T.; Tál, B.; Szepesi, T.; Suttrop, W.; Suarez Lopez, G.; Strumberger, E.; Stroth, U.; Stober, J.; Stieglitz, D.; Stejner, M.; Stegmeir, A.; Spolaore, M.; Spizzo, G.; Spacek, M.; Sozzi, C.; Sommariva, C.; Solano, E.; Snicker, A.; Sipilä, S.; Simpson, J.; Silvagni, D.; Silva, C.; Silva, A.; Sigalov, A.; Sieglin, B.; Siccinio, M.; Sias, G.; Shevelev, A.; Sheikh, U.; Sharapov, S.; Shalpegin, A.; Shabbir, A.; Seibold-Benjak, O.; Sciortino, F.; Schweinzer, J.; Schwarz-Selinger, T.; Schwarz, N.; Schuster, C.; Schubert, M.; Schrittwieser, R.; Schneider, P.A.; Schmitz, O.; Schmid, K.; Scholte, J.; Schlüter, A.; Schall, G.; Sauter, O.; Santos, J.; Sanchis Sanchez, L.; Samoylov, O.; Salmi, A.; Salewski, M.; Saarelma, S.; Ryter, F.; Ryan, D.A.; Rubel, M.; Rott, M.; Ronchi, G.; Rohde, V.; Rodriguez-Fernandez, P.; Rocchi, G.; Rivero Rodriguez, J.F.; Riesch, J.; Riedl, R.; Ricci, D.; Ribeiro, T.; Rettino, B.; Reiter, D.; Reisner, M.; Reiser, D.; Reimold, F.; Reich, M.; Réfy, D.; Redl, A.; Raupp, G.; Ratynskaia, S.; Ratta, G.; Rasmussen, J.; Ramisch, M.; Radovanovic, L.; Pütterich, T.; Puchmayr, J.; Porte, L.; Popa, A.; Poli, E.; Pokol, G.; Plyusnin, V.; Plöckl, B.; Plaum, B.; Plank, U.; Piron, C.; Petersson, P.; Peluso, E.; Peglau, M.; Paz-Soldan, C.; Pautasso, G.; Pau, A.; Papp, G.; Pan, O.; Oyola, P.; Olsen, J.; Ochoukov, R.; Nowak, S.; Novikau, I.; Nocente, M.; Nishizawa, T.; Nielsen, S.K.; Nielsen, A.H.; Neu, R.; Nem, R.D.; Nazikian, R.; Naulin, V.; Nabais, F.; Muraca, M.; Molina Cabrera, P.; Mitterauer, V.; Milanesio, D.; Michelini, M.; Meyer, H.; Merle, A.; Merkel, R.; Meng, G.; McDermott, R.; McCarthy, P. J.; Mayer, M.; Matos, F.; Martin, P.; Marrelli, L.; Markl, M.; Marchetto, C.; Maraschek, M.; Manz, P.; Mantsinen, M.; Mantica, P.; Manhard, A.; Mancini, A.; Maquet, V.; Maljaars, E.; Maj, O.; Maingi, R.; Mailloux, J.; Maier, H.; Magnanimo, A.; Madsen, J.; Maceina, T.; Lyssoivan, A.; Lunt, T.; Luhmann, N.C.; Di Cortemiglia, T. Luda; Lu, Z.; Liu, Y.; Lipschultz, B.; Lindl, H.; Linder, O.; Likonen, J.; Li, L.; Leuthold, N.; Lerche, E.; Leppin, L.; Lehnen, M.; Lang, P.T.; Lainer, P.; Lahtinen, A.; Laggner, F.; Lackner, K.; Labit, B.; Kurzan, B.; Kurki-Suonio, T.; Kulla, D.; Kudlacek, O.; Krieger, K.; Kreuzeder, A.; Krebs, I.; Krause, M.; Krämer-Flecken, A.; Kong, M.; Komm, M.; Koleva, M.; Kocsis, G.; Klossek, F.; Klevarova, V.; Hansen, S. Kjer; Kirk, A.; Kircher, M.; Khilkevitch, E.; Kernbichler, W.; Kendl, A.; Kazakov, Y.; Kasilov, S.; Käsemann, C.-P.; Karhunen, J.; Kappatou, A.; Kalis, J.; Kallenbach, A.; Joffrin, E.; Jensen, T.; Jenko, F.; Jaulmes, F.; van Vuuren, A. Jansen; Jaksic, N.; Jacob, W.; Jachmich, S.; Ivanova-Stanik, I.; Ionita-Schrittwieser, C.; Insulander Björk, K.; Illerhaus, J.; Iliasova, M.; Igochine, V.; Hunger, K.; Huber, A.; Hubbard, A.; Houben, A.; Höschen, T.; Horvath, L.; Hopf, C.; Hölzl, M.; Holm, J.H.; Hörmann, S.; Höfler, K.; Hobirk, J.; Hitzler, F.; Heyn, E.; Herrmann, A.; Heuraux, S.; Herschel, M.; Hennequin, P.; Henderson, S.; Hellsten, T.; Heinrich, P.; Heinemann, B.; Hayward-Schneider, T.; Hauer, V.; Harrison, J.; Harrer, G.; den Harder, N.; Happel, T.; Ham, C.; Hakola, A.H.; Hachmeister, D.; Günter, S.; Guimarais, L.; Gude, A.; Grover, O.; Groth, M.; Griener, M.; Greuner, H.; Grenfell, G.; Gräter, A.; Granucci, G.; Gradic, D.; Görler, T.; Gorini, G.; Goodman, T.; Gonzalez Martin, J.; Gonzalez, J.C.; Gobbin, M.; Glöggler, S.; Gleiter, T.; Girka, O.; Girka, I.; Giovannozzi, E.; Gil, L.; Gibson, S.; Giannone, L.; Geiger, B.; Munöz, M. Garcia; Garavaglia, S.; Gao, Y.; Gallo, A.; Gallart Escolà, D.; Galdon-Quiroga, J.; Galazka, K.; Futatani, S.; Fünfgelder, H.; Fuchs, J.C.; Fuchert, G.; Fröschle, M.; Frassinetti, L.; Ford, O.; Fischer, R.; Figueredo, A.; Ficker, O.; Felici, F.; Faugel, H.; Farnik, M.; Fantz, U.; Jimenez, D. Fajardo; Faitsch, M.; Fable, E.; Esposito, B.; Encheva, A.; Elgeti, S.; Eich, T.; Dux, R.; Duval, B.P.; Dunne, M.; Dreval, M.; Dunai, D.; Dominguez-Palacios Durán, J.J.; Dibon, M.; Di Siena, A.; Denner, P.; Delogu, R.; de Marné, P.; de Baar, M.; Day, C.; David, P.; Molin, A. Dal; D’Arcangelo, O.; Cziegler, I.; Cseh, G.; Cruz Zabala, D.J.; Croci, G.; Creely, A.J.; Cote, T.; Coster, D.; Costea, S.; Conway, G.; Colas, L.; Coenen, J.W.; Coelho, R.; Coda, S.; Clairet, F.; Cianfarani, C.; Chomiczewska, A.; Chankin, A.; Challis, C.; Cazzaniga, C.; Cavedon, M.; Cathey, A.; Castillo Castillo, A.; Castaldo, C.; Carvalho, P.; Carr, M.; Carlton, D.; Cano Megías, P.; Cannas, B.; Camenen, Y.; Burckhart, A.; Buhler, A.; Buchanan, J.; Brochard, F.; Brida, D.; Brezinsek, S.; Brenzke, M.; van den Brand, H.; Bottino, A.; Bottereau, C.; Böswirth, B.; Bortolon, A.; Bonanomi, N.; Bolzonella, T.; Body, T.; Bock, L.; Bock, A.; Bobkov, V.; Blanken, T.; Birkenmeier, G.; Bilato, R.; Bielajew, R.; Biancalani, A.; Bernert, M.; Bernardo, J.; Bergmann, M.; Bergmann, A.; Bauer, M.; Banon Navarro, A.; Bandaru, V.; Balden, M.; Asunta, O.; Astrain, M.; Artigues, V.; Arden, N.; Angioni, C.; Alessi, E.; International Fusion Energy Research Centre; National Institutes of Natural Sciences; Ministry of Education, Culture, Sports, Science and Technology; MEXT; European Commission; National Institute for Fusion Science; Japan Society for the Promotion of ScienceThe Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on the ASDEX-Upgrade tokamak, as demonstrated experimentally. The mechanism of the energetic-particle-driven geodesic acoustic mode excitation and the mode nonlinear evolution is not yet fully understood. In the present work, a first-principles simulation using the MEGA code investigated the mode properties in both the linear growth and nonlinear saturated phases. Here we show that the simulation successfully reproduced the excitation and coexistence of these two modes, and agreed with the experimental results well. Conclusive evidence showed that the resonance overlap is the excitation mechanism of the energetic-particle-driven geodesic acoustic mode. In the linear growth phase, energetic particles that satisfied different resonance conditions excited the Alfvén instability, which then caused energetic particle redistribution in phase space. These redistributed energetic particles caused resonance overlap, exciting the energetic-particle-driven geodesic acoustic mode in the nonlinear phase. © The Author(s) 2024.Item Time-resolved eye diagrams to exploit hidden high-energy branches in a nonlinear wideband vibration-energy harvester(American Physical Society, 2023-08-01) Paul, Kankana; Roy, Saibal; Amann, Andreas; Science Foundation Ireland; Horizon 2020A wideband vibration energy harvester with multiple nonlinear forces is investigated. The nonlinearities are due to repulsive magnets and hardening springs, which gives rise to multistabilities between a number of energy branches. Not all branches are accessible by a simple up or down sweep of the driving frequency and in particular the highest energy branch is often hidden, requiring a suitable frequency schedule to be accessed. Detailed theoretical understanding of the energy branch structure along with robust experimental methods are essential for characterizing each of the energy branches to enhance the energy output from such a vibration energy harvesting system. We introduce a graphical representation in the form of eye diagrams based on time-resolved measurements of acceleration and output voltage to study the dynamical features of the different branches. This generic approach allows us to optimize the design, which results in 1.3 mW of power generated at 1 g over the 44-Hz frequency bandwidth while maintaining a small footprint of 1.23 cm3. The energy conversion ratio of the energy harvester at 120-Hz drive frequency is 0.52 for the high-energy branch.Item Quantum heat engine based on a spin-orbit- and Zeeman-coupled Bose-Einstein condensate(American Physical Society, 2022-09-27) Li, Jing; Sherman, E. Ya; Ruschhaupt, Andreas; Science Foundation Ireland; Eusko Jaurlaritza; Ministerio de Ciencia e Innovación; European Regional Development FundWe explore the potential of a spin-orbit-coupled Bose-Einstein condensate for thermodynamic cycles. For this purpose we propose a quantum heat engine based on a condensate with spin-orbit and Zeeman coupling as a working medium. The cooling and heating are simulated by contacts of the condensate with an external magnetized media and demagnetized media. We examine the condensate ground-state energy and its dependence on the strength of the synthetic spin-orbit and Zeeman couplings and interatomic interaction. Then we study the efficiency of the proposed engine. The cycle has a critical value of spin-orbit coupling related to the engine’s maximum efficiency.Item SkipNet: an adaptive neural network equalization algorithm for future passive optical networking(Optica Publishing Group, 2024-10-08) Murphy, Stephen L.; Townsend, Paul D.; Antony, Cleitus; Science Foundation IrelandIn this paper, we propose an original adaptive neural network equalizer (NNE) algorithm named SkipNet, which is suitable for rapid training on a packet-by-packet basis for burst-mode non-linear equalization in upstream PON transmission. SkipNet uses the simple LMS algorithm and avoids complex neural network training algorithms such as backpropagation and mini-batch training. We demonstrate SkipNet on captured continuous mode 100 Gbit/s PAM4 signals using an SOA preamplifier to achieve the challenging 29 dB PON optical loss budget. The adaptive SkipNet equalizer is shown to overcome combinations of severe SOA patterning effects and fiber dispersion impairments to achieve >29dB dynamic range back-to-back and >22.9dB dynamic range for up to 81.6 ps/nm accumulated dispersion. It can adapt in as little as 250 training symbols to each impairment scenario, which is equivalent to existing FFE/DFE solutions, while matching the non-linear performance of previously proposed static NNE solutions. To the best of our knowledge, SkipNet is the first ever adaptive NNE framework that can realistically be trained and adapted on a packet-by-packet basis and within strict PON packet preamble lengths.Item Twist-and-turn dynamics of spin squeezing in bosonic Josephson junctions: Enhanced shortcuts-to-adiabaticity approach(American Physical Society, 2024-08-12) Odelli, Manuel; Ruschhaupt, Andreas; Stojanović, Vladimir M.; Science Foundation Ireland; Deutsche ForschungsgemeinschaftThe twist-and-turn dynamics of spin squeezing results from the interplay of the one-axis-twisting (nonlinear in the collective-spin operators) and the transverse-field turning (linear) term in the underlying Lipkin-Meshkov-Glick-type Hamiltonian, both with constant (time-independent) prefactors. Using shortcuts to adiabaticity (STA) and the recently developed enhanced version thereof (eSTA), we demonstrate here that dynamics of this type can be utilized for a fast and robust preparation of spin-squeezed states in internal bosonic Josephson junctions, i.e., condensates of cold bosonic atoms in two different internal (hyperfine) states (single-boson modes) coupled through Rabi rotations. Assuming that the initial state of this system is its ground state for a given initial value of the (time-dependent) linear coupling strength and that the nonlinear coupling strength remains constant, we set out to determine the time dependence of the linear (Rabi) coupling strength that allows for the generation of spin-squeezed states using the STA- and eSTA-based approaches. We then characterize the modified twist-and-turn dynamics of this system by evaluating the coherent spin-squeezing and number-squeezing parameters, as well as the fidelity of the target spin-squeezed states. In this way, we show that the eSTA approach allows for a particularly robust realization of strongly spin-squeezed states in this system, consistently outperforming its adiabatic and STA-based counterparts, even for systems with several hundred particles. Our method could also be employed for the generation of metrologically-useful non-Gaussian states.