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Papers

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Physics

Watch Physics

Tuesday 18 August

Solar and Stellar Astrophysics

3D simulations of magnetospheric accretion in T Tauri stars: I. Disk truncation, stellar torques, and application to observations

George Pantolmos, Claudio Zanni and Jérôme Bouvier

Young stars accrete material from their circumstellar disk through their magnetosphere and undergo contraction; these two processes impact their rotational evolution. We investigate stable and unstable accretion regimes (due to the interchange instability) and examine the associated stellar torques to assess the spin evolution of young stars. We performed 3D MHD simulations of disk accretion onto an inclined stellar dipole. We ran 21 simulations with varying stellar rotation rates, dipole field strengths and obliquities, and mass accretion rates. We find that stars with a ratio of truncation to corotation radius $R_t/R_{co} \gtrsim 0.80-0.85$ accrete via a stable regime, while accretion becomes unstable otherwise. In addition, our $R_t/R_{\ast}$ parametrization weakly depends on the mass accretion rate and the dipolar intensity, while strongly depending on the stellar rotation rate. We derive torque formulae for each flow component affecting the stellar rotation, i.e., accretion, magnetospheric ejections and stellar winds. Finally, we apply our results to a sample of young stars with measured magnetic fields, mass accretion rates, and rotational periods and find that most of them should currently accrete in an unstable regime and undergo spin-up torques. Our study confirms and expands upon previous results. Unstable accretion should lead to a net spin-up torque on the central star, while stable accretion can lead to stellar spin-down. When applying our truncation radius and torque prescriptions to observational data, we find that most young stars in our sample should be in a spin-up state. Thus, the angular momentum problem for young stars remains.
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Materials Science

Optical decoherence in Er$^{3+}$-doped CeO$_2$ spin qubit platforms

Vrindaa Somjit, Ignas Masiulionis, Gregory D. Grant et al. (+7 more)

Erbium ions (Er$^{3+}$) in cerium dioxide (CeO$_2$) represent a promising spin-photon interface for quantum communication, but the mechanisms limiting their optical coherence remain poorly understood. Using periodic hybrid density functional theory calculations with finite-size corrections, we identify Ce$^{3+}$ polarons and their complexes with oxygen vacancies and Er$^{3+}$ dopants as likely sources of optical decoherence. These defects exhibit finite photoionization cross-sections at 0.8 eV, coinciding with both the laser excitation energy used experimentally and the emission energy of Er$^{3+}$. This resonance enables photoionization of the polarons and photoluminescence quenching of Er$^{3+}$, leading to the broadening of optical linewidths, shortening of excited-state lifetimes, and introduction of charge noise. Our concentration-dependent photocurrent measurements in Er$^{3+}$-doped CeO$_2$ films under 0.8 eV illumination validate the predicted decoherence pathway. Our combined computational and experimental results identify a concrete defect-engineering target for improving the Er$^{3+}$-doped CeO$_2$ platform, and point to a decoherence mechanism likely relevant to other Er$^{3+}$-doped multivalent-oxide quantum platforms.
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All authors Vrindaa Somjit, Ignas Masiulionis, Gregory D. Grant, Weiguo Jing, Matteo Giantomassi, Supratik Guha, Gian-Marco Rignanese, F. Joseph Heremans, Jiefei Zhang, Giulia Galli

High Energy Physics (Phenomenology)

Resolved Photon Processes: A Tribute to Rohini Godbole

Manuel Drees

Hadrons are particles composed of elementary quarks and gluons, which have strong interactions described by Quantum Chromodynamics (QCD); examples are protons and neutrons, which bind to form atomic nuclei. In contrast, photons are usually thought of as the elementary force carriers of quantum electrodynamics (QED). However, at the quantum level a photon can fluctuate into a quark antiquark pair. At sufficiently high energies these virtual quarks can become real, physical particles by interacting with other particles, in particular with other hadrons. In this way photons with energies exceeding a few GeV acquire properties of a hadron. Resolved photon processes are reactions that probe these hadronic properties. These processes often dominate the production of hadronic final states, including jets (sprays of collimated hadrons), at electron–proton and electron–positron colliders. Implications of this for backgrounds at future high–energy lepton colliders remain poorly understood.
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Earth and Planetary Astrophysics

Triggered Fragmentation in Self-Gravitating Protoplanetary discs: Cooling, Mass Movement and Instability

Pratishtha Rawat, Farzana Meru and Rebecca Nealon

Previous three-dimensional hydrodynamical simulations of gravitationally unstable discs have shown that the formation of a single fragment can trigger the formation of subsequent fragments. This behaviour was attributed to changes in the surface mass density caused by the interaction between the first fragment and the disc material. This study reanalyses those simulations to see if the surface mass density was the sole driver. Our results reveal that both surface mass density and sound speed can contribute to the formation of additional fragments. Beyond the general cooling typical of such discs, the inwards movement of cool material from the outer disc, driven by the formation of the first fragment, can enhance fragmentation in the inner regions. We also identify that interactions between the midplane gas and the cooler upper layers of the disc can facilitate additional cooling. Triggered fragmentation can create a unique planet-formation environment by redistributing material across the disc, potentially leading to chemically distinct fragments from those formed in-situ.
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High Energy Physics (Experiment)

Search for $B$ meson decays to multimuon final states

LHCb collaboration: R. Aaij, M. Abdelfatah, A.S.W. Abdelmotteleb et al. (+1130 more)

A search for decays of $B$ mesons to final states with four or six muons using $pp$ collision data recorded by the LHCb experiment corresponding to an integrated luminosity of $5.4~\text{fb}^{-1}$ is presented. The decay modes of interest are $B_{(s)}^0 \rightarrow \mu^+\mu^-\mu^+\mu^-$, $B^+ \rightarrow K^+\mu^+\mu^-\mu^+\mu^-$, $B_{(s)}^0 \rightarrow \mu^+\mu^-\mu^+\mu^-\mu^+\mu^-$ and $B^+ \rightarrow K^+\mu^+\mu^-\mu^+\mu^-\mu^+\mu^-$, proceeding via both prompt and long-lived intermediate particles. No evidence for any of the signal modes is found, and upper limits spanning the range of $0.6\times10^{-9}$ to $5.4\times10^{-7}$ at the $95\%$ confidence level are set on their branching fractions, depending on the intermediate-particle masses and lifetimes. In addition, mass-integrated limits across the intermediate-particle lifetime ranges considered in this analysis are determined.
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All authors LHCb collaboration: R. Aaij, M. Abdelfatah, A.S.W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A.A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C.A. Aidala, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, R. Aleksiejunas, F. Alessio, P. Alvarez Cartelle, S. Amato, J.L. Amey, Y. Amhis, L. An, L. Anderlini, M. Andersson, P. Andreola, M. Andreotti, S. Andres Estrada, A. Anelli, D. Ao, C. Arata, F. Archilli, Z. Areg, M. Argenton, S. Arguedas Cuendis, L. Arnone, M. Artuso, E. Aslanides, R. Ataíde Da Silva, M. Atzeni, B. Audurier, J.A. Authier, D. Bacher, I. Bachiller Perea, S. Bachmann, M. Bachmayer, J.J. Back, Z.B. Bai, V. Balagura, A. Balboni, W. Baldini, Z. Baldwin, L. Balzani, H. Bao, J. Baptista de Souza Leite, C. Barbero Pretel, M. Barbetti, I.R. Barbosa, R.J. Barlow, M. Barnyakov, S. Baron, S. Barsuk, W. Barter, J. Bartz, S. Bashir, B. Batsukh, P.B. Battista, A. Bavarchee, A. Bay, A. Beck, M. Becker, F. Bedeschi, I.B. Bediaga, N.A. Behling, S. Belin, A. Bellavista, I. Belov, I. Belyaev, G. Bencivenni, E. Ben-Haim, J.L.M. Berkey, R. Bernet, A. Bertolin, F. Betti, J. Bex, O. Bezshyyko, S. Bhattacharya, M.S. Bieker, N.V. Biesuz, A. Biolchini, M. Birch, F.C.R. Bishop, A. Bitadze, A. Bizzeti, T. Blake, F. Blanc, J.E. Blank, S. Blusk, J.A. Boelhauve, O. Boente Garcia, T. Boettcher, A. Bohare, C. Bolognani, R. Bolzonella, R.B. Bonacci, A. Bordelius, F. Borgato, S. Borghi, M. Borsato, J.T. Borsuk, E. Bottalico, S.A. Bouchiba, M. Bovill, T.J.V. Bowcock, A. Boyer, C. Bozzi, J.D. Brandenburg, A. Brea Rodriguez, N. Breer, C. Breitfeld, J. Brodzicka, J. Brown, D. Brundu, E. Buchanan, M. Burgos Marcos, C. Burr, C. Buti, J.S. Butter, J. Buytaert, W. Byczynski, S. Cadeddu, H. Cai, Y. Cai, A. Caillet, R. Calabrese, L. Calefice, M. Calvi, M. Calvo Gomez, P. Camargo Magalhaes, J.I. Cambon Bouzas, P. Campana, A.C. Campos, A.F. Campoverde Quezada, Y. Cao, S. Capelli, M. Caporale, L. Capriotti, R. Caravaca-Mora, A. Carbone, L. Carcedo Salgado, R. Cardinale, A. Cardini, P. Carniti, L. Carus, A. Casais Vidal, R. Caspary, G. Casse, M. Cattaneo, G. Cavallero, V. Cavallini, S. Celani, I. Celestino, S. Cesare, A.J. Chadwick, I. Chahrour, M. Charles, Ph. Charpentier, E. Chatzianagnostou, R. Cheaib, M. Chefdeville, C. Chen, J. Chen, S. Chen, Z. Chen, A. Chen Hu, M. Cherif, S. Chernyshenko, X. Chiotopoulos, G. Chizhik, V. Chobanova, M. Chrzaszcz, V. Chulikov, P. Ciambrone, X. Cid Vidal, P. Cifra, P.E.L. Clarke, M. Clemencic, H.V. Cliff, J. Closier, C. Cocha Toapaxi, V. Coco, J. Cogan, E. Cogneras, L. Cojocariu, S. Collaviti, P. Collins, T. Colombo, M. Colonna, A. Comerma-Montells, L. Congedo, J. Connaughton, A. Contu, N. Cooke, G. Cordova, C. Coronel, I. Corredoira, A. Correia, G. Corti, G.C. Costantino, J. Cottee Meldrum, B. Couturier, D.C. Craik, N. Crepet, M. Cruz Torres, M. Cubero Campos, E. Curras Rivera, R. Currie, C.L. Da Silva, X. Dai, J. Dalseno, C. D'Ambrosio, G. Darze, A. Davidson, J.E. Davies, O. De Aguiar Francisco, C. De Angelis, F. De Benedetti, J. de Boer, K. De Bruyn, S. De Capua, M. De Cian, U. De Freitas Carneiro Da Graca, E. De Lucia, J.M. De Miranda, L. De Paula, M. De Serio, P. De Simone, F. De Vellis, J.A. de Vries, F. Debernardis, D. Decamp, S. Dekkers, L. Del Buono, B. Delaney, J. Deng, V. Denysenko, O. Deschamps, F. Dettori, B. Dey, P. Di Nezza, S. Ding, Y. Ding, L. Dittmann, A.D. Docheva, A. Doheny, C. Dong, F. Dordei, A.C. dos Reis, A.D. Dowling, L. Dreyfus, W. Duan, P. Duda, L. Dufour, V. Duk, P. Durante, M.M. Duras, J.M. Durham, O.D. Durmus, K. Duwe, A. Dziurda, S. Easo, E. Eckstein, U. Egede, S. Eisenhardt, E. Ejopu, L. Eklund, M. Elashri, D. Elizondo Blanco, J. Ellbracht, S. Ely, A. Ene, J. Eschle, T. Evans, F. Fabiano, S. Faghih, L.N. Falcao, B. Fang, R. Fantechi, L. Fantini, M. Faria, K. Farmer, F. Fassin, D. Fazzini, L. Felkowski, C. Feng, M. Feng, A. Fernandez Casani, M. Fernandez Gomez, A.D. Fernez, F. Ferrari, F. Ferreira Rodrigues, M. Ferrillo, R.A. Fini, M. Fiorini, M. Firlej, K.L. Fischer, D.S. Fitzgerald, C. Fitzpatrick, T. Fiutowski, F. Fleuret, A. Fomin, M. Fontana, L.A. Foreman, R. Forty, D. Foulds-Holt, V. Franco Lima, M. Franco Sevilla, M. Frank, E. Franzoso, G. Frau, C. Frei, D.A. Friday, J. Fu, Y. Fu, Q. Führing, T. Fulghesu, G. Galati, M.D. Galati, A. Gallas Torreira, D. Galli, S. Gambetta, M. Gandelman, P. Gandini, B. Ganie, H. Gao, R. Gao, T.Q. Gao, Y. Gao, Y. Gao, Y. Gao, L.M. Garcia Martin, P. Garcia Moreno, J. García Pardiñas, P. Gardner, L. Garrido, C. Gaspar, A. Gavrikov, E. Gersabeck, M. Gersabeck, T. Gershon, S. Ghizzo, Z. Ghorbanimoghaddam, F.I. Giasemis, V. Gibson, H.K. Giemza, A.L. Gilman, M. Giovannetti, A. Gioventù, L. Girardey, M.A. Giza, F.C. Glaser, V.V. Gligorov, C. Göbel, L. Golinka-Bezshyyko, E. Golobardes, A. Golutvin, S. Gomez Fernandez, W. Gomulka, F. Goncalves Abrantes, I. Gonçales Vaz, M. Goncerz, G. Gong, J.A. Gooding, C. Gotti, E. Govorkova, J.P. Grabowski, L.A. Granado Cardoso, R. Grande Quartieri, E. Graugés, E. Graverini, L. Grazette, G. Graziani, A.T. Grecu, N.A. Grieser, L. Grillo, C. Gu, M. Guarise, L. Guerry, A.-K. Guseinov, Y. Guz, T. Gys, K. Habermann, T. Hadavizadeh, C. Hadjivasiliou, G. Haefeli, C. Haen, S. Haken, G. Hallett, P.M. Hamilton, Q. Han, X. Han, S. Hansmann-Menzemer, N. Harnew, T.J. Harris, L. Hartman, M. Hartmann, S. Hashmi, J. He, N. Heatley, A. Hedes, F. Hemmer, C. Henderson, R. Henderson, R.D.L. Henderson, A.M. Hennequin, K. Hennessy, J. Herd, P. Herrero Gascon, J. Heuel, A. Heyn, A. Hicheur, G. Hijano Mendizabal, J. Horswill, R. Hou, Y. Hou, D.C. Houston, N. Howarth, W. Hu, X. Hu, W. Hulsbergen, R.J. Hunter, D. Hutchcroft, M. Idzik, P. Ilten, A. Iohner, H. Jage, S.J. Jaimes Elles, S. Jakobsen, T. Jakoubek, E. Jans, A. Jawahery, C. Jayaweera, A. Jelavic, V. Jevtic, Z. Jia, E. Jiang, X. Jiang, Y. Jiang, Y.J. Jiang, E. Jimenez Moya, N. Jindal, M. John, A. John Rubesh Rajan, D. Johnson, C.R. Jones, S. Joshi, B. Jost, J. Juan Castella, N. Jurik, I. Juszczak, K. Kalecinska, D. Kaminaris, S. Kandybei, M. Kane, Y. Kang, C. Kar, M. Karacson, A. Kauniskangas, J.W. Kautz, M.K. Kazanecki, F. Keizer, M. Kenzie, T. Ketel, B. Khanji, S. Kholodenko, G. Khreich, F. Kiraz, T. Kirn, V.S. Kirsebom, N. Kleijne, A. Kleimenova, D. Klekots, K. Klimaszewski, M.R. Kmiec, T. Knospe, R. Kolb, S. Koliiev, L. Kolk, A. Konoplyannikov, P. Kopciewicz, P. Koppenburg, A. Korchin, I. Kostiuk, O. Kot, S. Kotriakhova, E. Kowalczyk, O. Kravcov, M. Kreps, W. Krupa, W. Krzemien, O. Kshyvanskyi, S. Kubis, M. Kucharczyk, A. Kupsc, V. Kushnir, B. Kutsenko, J. Kvapil, I. Kyryllin, D. Lacarrere, P. Laguarta Gonzalez, A. Lai, A. Lampis, D. Lancierini, C. Landesa Gomez, J.J. Lane, G. Lanfranchi, C. Langenbruch, T. Latham, F. Lazzari, C. Lazzeroni, R. Le Gac, H. Lee, R. Lefèvre, M. Lehuraux, E. Lemos Cid, O. Leroy, T. Lesiak, E.D. Lesser, B. Leverington, A. Li, C. Li, C. Li, H. Li, J. Li, K. Li, L. Li, P. Li, P.-R. Li, Q. Li, T. Li, T. Li, W. Li, Y. Li, Y. Li, Y. Li, Z. Li, Z. Lian, Q. Liang, X. Liang, Z. Liang, S. Libralon, A. Lightbody, T. Lin, R. Lindner, H. Linton, R. Litvinov, D. Liu, F.L. Liu, G. Liu, K. Liu, S. Liu, W. Liu, Y. Liu, Y. Liu, Y.L. Liu, G. Loachamin Ordonez, I. Lobo, A. Lobo Salvia, A. Loi, T. Long, F.C.L. Lopes, J.H. Lopes, A. Lopez Huertas, C. Lopez Iribarnegaray, Q. Lu, C. Lucarelli, D. Lucchesi, M. Lucio Martinez, Y. Luo, A. Lupato, M. Lupberger, E. Luppi, K. Lynch, S. Lyu, X.-R. Lyu, H. Ma, S. Maccolini, F. Machefert, F. Maciuc, B. Mack, I. Mackay, L.M. Mackey, L.R. Madhan Mohan, M.J. Madurai, D. Magdalinski, J.J. Malczewski, S. Malde, L. Malentacca, G. Manca, G. Mancinelli, C. Mancuso, R. Manera Escalero, A. Mangalasseri, F.M. Manganella, D. Manuzzi, S. Mao, D. Marangotto, J.F. Marchand, R. Marchevski, U. Marconi, E. Mariani, S. Mariani, C. Marin Benito, J. Marks, A.M. Marshall, L. Martel, G. Martelli, G. Martellotti, L. Martinazzoli, M. Martinelli, C. Martinez, D. Martinez Gomez, D. Martinez Santos, F. Martinez Vidal, A. Martorell i Granollers, A. Massafferri, R. Matev, A. Mathad, C. Matteuzzi, K.R. Mattioli, A. Mauri, E. Maurice, J. Mauricio, P. Mayencourt, J. Mazorra de Cos, M. Mazurek, D. Mazzanti Tarancon, M. McCann, N.T. McHugh, A. McNab, R. McNulty, B. Meadows, S.E.R. Medaer, D. Melnychuk, D. Mendoza Granada, P. Menendez Valdes Perez, F.M. Meng, M. Merk, A. Merli, L. Meyer Garcia, D. Miao, H. Miao, M. Mikhasenko, D.A. Milanes, A. Minotti, E. Minucci, B. Mitreska, D.S. Mitzel, R. Mocanu, A. Modak, L. Moeser, R.D. Moise, E.F. Molina Cardenas, T. Mombächer, M. Monk, T. Monnard, S. Monteil, A. Morcillo Gomez, G. Morello, M.J. Morello, M.P. Morgenthaler, A. Moro, J. Moron, W. Morren, A.B. Morris, A.G. Morris, R. Mountain, Z. Mu, N. Muangkod, E. Muhammad, F. Muheim, M. Mulder, K. Müller, F. Muñoz-Rojas, V. Mytrochenko, P. Naik, T. Nakada, R. Nandakumar, G. Napoletano, I. Nasteva, M. Needham, N. Neri, S. Neubert, N. Neufeld, J. Nicolini, D. Nicotra, E.M. Niel, L. Nisi, Q. Niu, B.K. Njoki, P. Nogarolli, P. Nogga, C. Normand, J. Novoa Fernandez, G. Nowak, H.N. Nur, A. Oblakowska-Mucha, T. Oeser, O. Okhrimenko, R. Oldeman, F. Oliva, E. Olivart Pino, M. Olocco, R.H. O'Neil, J.S. Ordonez Soto, D. Osthues, J.M. Otalora Goicochea, P. Owen, A. Oyanguren, O. Ozcelik, F. Paciolla, A. Padee, K.O. Padeken, B. Pagare, T. Pajero, A. Palano, L. Palini, M. Palutan, C. Pan, X. Pan, S. Panebianco, S. Paniskaki, L. Paolucci, A. Papanestis, M. Pappagallo, L.L. Pappalardo, C. Pappenheimer, C. Parkes, D. Parmar, G. Passaleva, D. Passaro, A. Pastore, M. Patel, J. Patoc, C. Patrignani, A. Paul, C.J. Pawley, A. Pellegrino, J. Peng, X. Peng, M. Pepe Altarelli, S. Perazzini, H. Pereira Da Costa, M. Pereira Martinez, A. Pereiro Castro, C. Perez, P. Perret, A. Perrevoort, A. Perro, M.J. Peters, K. Petridis, A. Petrolini, S. Pezzulo, J.P. Pfaller, H. Pham, L. Pica, M. Piccini, L. Piccolo, B. Pietrzyk, R.N. Pilato, D. Pinci, F. Pisani, M. Pizzichemi, V.M. Placinta, M. Plo Casasus, T. Poeschl, F. Polci, M. Poli Lener, A. Poluektov, I. Polyakov, E. Polycarpo, S. Ponce, D. Popov, K. Popp, K. Prasanth, C. Prouve, D. Provenzano, V. Pugatch, A. Puicercus Gomez, G. Punzi, J.R. Pybus, Q. Qian, W. Qian, N. Qin, R. Quagliani, R.I. Rabadan Trejo, B. Rachwal, R. Racz, J.H. Rademacker, M. Rama, M. Ramírez García, V. Ramos De Oliveira, M. Ramos Pernas, M.S. Rangel, G. Raven, M. Rebollo De Miguel, F. Redi, J. Reich, F. Reiss, Z. Ren, P.K. Resmi, M. Ribalda Galvez, R. Ribatti, G. Ricart, D. Riccardi, S. Ricciardi, K. Richardson, M. Richardson-Slipper, F. Riehn, K. Rinnert, P. Robbe, G. Robertson, E. Rodrigues, A. Rodriguez Alvarez, E. Rodriguez Fernandez, J.A. Rodriguez Lopez, E. Rodriguez Rodriguez, J. Roensch, A. Rogovskiy, D.L. Rolf, P. Roloff, V. Romanovskiy, A. Romero Vidal, G. Romolini, F. Ronchetti, T. Rong, M. Rotondo, M.S. Rudolph, M. Ruiz Diaz, J. Ruiz Vidal, J.J. Saavedra-Arias, J.J. Saborido Silva, D. Sahoo, N. Sahoo, B. Saitta, M. Salomoni, I. Sanderswood, R. Santacesaria, C. Santamarina Rios, M. Santimaria, L. Santoro, E. Santovetti, A. Saputi, A. Sarnatskiy, G. Sarpis, M. Sarpis, C. Satriano, A. Satta, M. Saur, H. Sazak, F. Sborzacchi, A. Scarabotto, S. Schael, S. Scherl, M. Schiller, H. Schindler, M. Schmelling, B. Schmidt, N. Schmidt, S. Schmitt, H. Schmitz, O. Schneider, A. Schopper, N. Schulte, M.H. Schune, G. Schwering, B. Sciascia, A. Sciuccati, G. Scriven, I. Segal, S. Sellam, M. Senghi Soares, A. Sergi, N. Serra, L. Sestini, B. Sevilla Sanjuan, Y. Shang, D.M. Shangase, R.S. Sharma, L. Shchutska, T. Shears, J. Shen, Z. Shen, S. Sheng, B. Shi, J. Shi, Q. Shi, W.S. Shi, E. Shmanin, R. Silva Coutinho, G. Simi, S. Simone, M. Singha, I. Siral, N. Skidmore, T. Skwarnicki, M.W. Slater, E. Smith, M. Smith, L. Soares Lavra, M.D. Sokoloff, F.J.P. Soler, A. Solomin, K. Solovieva, N.S. Sommerfeld, R. Song, Y. Song, Y. Song, Y.S. Song, F.L. Souza De Almeida, B. Souza De Paula, K.M. Sowa, E. Spadaro Norella, E. Spedicato, J.G. Speer, P. Spradlin, F. Stagni, M. Stahl, S. Stahl, S. Stanislaus, M. Stefaniak, O. Steinkamp, F. Suljik, J. Sun, L. Sun, M. Sun, D. Sundfeld, W. Sutcliffe, P. Svihra, V. Svintozelskyi, K. Swientek, F. Swystun, A. Szabelski, T. Szumlak, Y. Tan, Y. Tang, Y.T. Tang, M.D. Tat, J.A. Teijeiro Jimenez, F. Terzuoli, F. Teubert, E. Thomas, D.J.D. Thompson, A.R. Thomson-Strong, H. Tilquin, V. Tisserand, S. T'Jampens, M. Tobin, T.T. Todorov, L. Tomassetti, G. Tonani, X. Tong, T. Tork, L. Toscano, D.Y. Tou, C. Trippl, G. Tuci, N. Tuning, L.H. Uecker, A. Ukleja, A. Upadhyay, B. Urbach, A. Usachov, U. Uwer, V. Vagnoni, A. Vaitkevicius, V. Valcarce Cadenas, G. Valenti, N. Valls Canudas, J. van Eldik, H. Van Hecke, E. van Herwijnen, C.B. Van Hulse, R. Van Laak, M. van Veghel, G. Vasquez, R. Vazquez Gomez, P. Vazquez Regueiro, C. Vázquez Sierra, S. Vecchi, J. Velilla Serna, J.J. Velthuis, M. Veltri, A. Venkateswaran, M. Verdoglia, M. Vesterinen, W. Vetens, D. Vico Benet, P. Vidrier Villalba, M. Vieites Diaz, X. Vilasis-Cardona, E. Vilella Figueras, A. Villa, P. Vincent, B. Vivacqua, F.C. Volle, D. vom Bruch, K. Vos, C. Vrahas, J. Wagner, J. Walsh, N. Walter, E.J. Walton, G. Wan, A. Wang, B. Wang, C. Wang, G. Wang, H. Wang, J. Wang, J. Wang, J. Wang, J. Wang, M. Wang, N.W. Wang, R. Wang, X. Wang, X. Wang, X. Wang, X.W. Wang, Y. Wang, Y. Wang, Y.H. Wang, Z. Wang, Z. Wang, J.A. Ward, M. Waterlaat, N.K. Watson, D. Websdale, Y. Wei, Z. Weida, J. Wendel, B.D.C. Westhenry, C. White, M. Whitehead, E. Whiter, A.R. Wiederhold, D. Wiedner, M.A. Wiegertjes, C. Wild, G. Wilkinson, M.K. Wilkinson, M. Williams, M.J. Williams, M.R.J. Williams, R. Williams, S. Williams, Z. Williams, F.F. Wilson, M. Winn, W. Wislicki, M. Witek, L. Witola, T. Wolf, E. Wood, G. Wormser, S.A. Wotton, H. Wu, J. Wu, X. Wu, Y. Wu, Z. Wu, K. Wyllie, S. Xian, Z. Xiang, Y. Xie, T.X. Xing, A. Xu, L. Xu, M. Xu, R. Xu, Z. Xu, Z. Xu, Z. Xu, Z. Xu, S. Yadav, K. Yang, X. Yang, Y. Yang, Y. Yang, Z. Yang, Z. Yang, H. Yeung, H. Yin, X. Yin, C.Y. Yu, J. Yu, X. Yuan, Y Yuan, J.A. Zamora Saa, M. Zavertyaev, M. Zdybal, F. Zenesini, C. Zeng, M. Zeng, S.H Zeng, C. Zhang, C. Zhang, D. Zhang, J. Zhang, L. Zhang, R. Zhang, S. Zhang, S.L. Zhang, Y. Zhang, Z. Zhang, J. Zhao, Y. Zhao, A. Zhelezov, S.Z. Zheng, X.Z. Zheng, Y. Zheng, T. Zhou, X. Zhou, V. Zhovkovska, L.Z. Zhu, X. Zhu, X. Zhu, Y. Zhu, V. Zhukov, J. Zhuo, D. Zuliani, G. Zunica

Quantum Physics

A quantum optical concept of attosecond pulses: the attoquants

Sándor Varró and Ákos Gombkötő

High-harmonic generation (HHG) is conventionally understood to produce attosecond pulse trains only when the emitted harmonics are mutually phase-locked, in accordance with the classical theory of mode-locking. Such locking is necessary for pulse synthesis when the harmonic field is in a separable multimode quantum state. This requirement, however, can be circumvented entirely for harmonic combs exhibiting intermodal entanglement. We introduce a novel family of multimode quantum states, termed attoquants: states associated with highly structured pulse trains that are inherently insensitive to relative phases. As a concrete example, we analyse the coherent permanent state, constructed as a completely symmetric superposition of products of coherent states over all permutations of a fixed parameter set. It is shown analytically that its electric-field expectation value is a locked Fourier superposition of the driving-field harmonics, yielding an attosecond pulse train without requiring mode-locking. We further calculate the photon statistics, the Wigner function, and the logarithmic negativity of this state, confirming it to be genuinely nonclassical and entangled. Finally, we offer a phenomenological interpretation for the generation of such entangled states during HHG, as a consequence of multi-atom effects. Since the coherence volume of the driving field greatly exceeds that of its harmonics, a collectively-driven cluster of atoms can radiate the individual harmonics as spatially resolved, but fundamentally indistinguishable sources. This can generate the permutation-symmetric entanglement structure of an attoquant.
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Soft Condensed Matter

A solid-state theory for dense cylindrical packings of balls

Luke K. Davis and Alexander R. Klotz

We develop an analytical theory for the dense packing of hard spheres in cylinders. Physically, our theory consists of a finite cylindrical masking of a close-packed three-dimensional solid and covers the entire range of cylinder aspect ratios, thus going beyond efforts that are focused on very tall cylinders in a narrow range of widths. We explicitly derive an exact equation for resulting packing fractions, valid for any regular lattice, and it provides a basis to understand the oscillations and scaling of volume fractions that have appeared in previous works. Our analytical relation serves as a rigorous lower bound and to tighten it we derive, and implement, an efficient mathematical procedure to optimize the orientation of the cylinder. Furthermore, we suggest simple techniques to improve on the predicted packings. Overall, we provide a general theoretical foundation for the packing of balls in cylinders, valid for all container sizes.
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General Relativity and Quantum Cosmology · Cross-listed from math.DG

Conformally Einstein anti-self-dual spaces and their generalisations

Timothy Moy

We study the existence of Einstein scales and compatible metrics in Grassmannian geometry. As a special case, this includes the conformal-to-Einstein problem for anti-self-dual (ASD) conformal structures. In the ASD setting, given a genericity condition algebraic in the Weyl curvature, we obtain necessary and sufficient conditions for the existence of a local Einstein scale that refine those previously appearing in the literature. We also prove that in Riemannian signature, a non-Ricci-flat ASD-Kähler metric is locally conformally Einstein if and only if it has a holomorphic Killing vector field with anti-self-dual derivative proportional to the Ricci spinor. Next, we consider some generalisations of the ASD conformal-to-Einstein problem for $(2n,2)$-Grassmannian structures. When $n > 1$, given an analogous genericity condition, we obtain necessary and sufficient conditions for the existence of a local Einstein scale. Using tractor calculus, we obtain algebraic obstructions to the existence of compatible metrics and show that the unique submaximally symmetric model of the geometry has the submaximal number of linearly independent compatible metrics.
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Quantum Physics

Quantum Circuit for General Unitary: Improved T-count via Block Flattening and Dilation

Pei Yuan, Shengyu Zhang and Wei Zi

Synthesizing arbitrary $n$-qubit unitaries using as few non-Clifford gates as possible is a central problem in fault-tolerant quantum compilation. We present a Clifford+$T$ quantum circuit construction that approximately implements any classically specified unitary to within error $\epsilon$ and achieves a worst-case $T$-count with leading exponential scaling of $2^{5n/4}$ whenever $\log(1/\epsilon)=\operatorname{poly}(n)$. This improves upon the best previous $2^{4n/3}$ scaling. The key innovation lies in treating the target unitary as a single block-encoded object rather than a long product of simpler operations. A technique of block flattening controls the normalization while preserving an efficient implementation of the block encoding; subsequently, quantum singular value transformation maps its common singular value to one, thereby recovering the target unitary.
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Computational Physics

Investigation of the Asymptotic Properties of Active Impedance in Large Finite Array Antennas

Harald Hultin, Lucas Åkerstedt and B. L. G. Jonsson

This paper presents an improved full-wave solver for finite array antennas, and uses this solver to examine asymptotic properties of active impedance for large regular arrays. The improved solver is based on a preconditioning scheme that has been adapted for use on more general finite geometries, and an improved data structure. These two improvements result in a fast and stable solver with a lower memory footprint. By investigating the active impedance of finite arrays it is found that, even for arrays with 1000 elements, asymptotic behavior may differ from infinite arrays. Tied to these properties, different predictors on how the active impedance of the center element in the array behaves are presented. The two best predictors work very well for the wideband arrays investigated, and may be used to decide when array approximations, such as unit cell methods, are appropriate, rather than general statements on array size.
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Instrumentation and Methods for Astrophysics

Accurately simulating gain and clock-induced charge production in the EMCCD gain register

Kevin J. Ludwick

An electron-multiplying charge-coupled device (EMCCD) is capable of precise detections in low-signal environments, able to detect a single photon through electron multiplication. It has many applications, such as faint-target astronomy, quantum optics, molecule tracing, and others, and it will be used for faint companion detection in the Roman Telescope's coronagraph instrument. In an EMCCD, photons hit the pixels, and photo-electrons are created; these are multiplied via impact ionization as they travel through the gain register from one gain stage to the next. A high gain means a high multiplication factor, and this is achieved through a high voltage difference across a gain stage. If the gain is high enough, the chance of clock-induced charge (CIC) production in the gain register increases. The probability distribution function governing the gain process typically used only accounts for charge multiplication if one or more electrons enter the gain register. I discuss my implementation of the simulation of this effect and its customization in emccd_detect, the EMCCD detector simulator used for the Roman Telescope. In addition, the simulator has been updated to use the exact binomial distribution for EM gain instead of the approximate Gamma distribution usually used in the literature, which is only valid for large counts. I also examine some EMCCD data and show through maximum likelihood estimation with CIC_gain_register that the data conform better to the binomial distribution versus the approximate Gamma/Erlang distribution. The use of the modified distribution would in principle improve the fidelity of Roman's testing and lead to better EMCCD calibration and more accurate signal extraction from a frame.
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Mesoscale and Nanoscale Physics

The Deformed Image Vortex Ansatz: A Perturbation-Aware Description of Magnetic Vortices in In-Plane Fields

Thomas G. Coppée, Colin Ducarme, Simon de Wergifosse et al. (+1 more)

Thiele-based descriptions of magnetic vortex dynamics in thin ferromagnetic nanodots rely on magnetization ansätze that describe the equilibrium texture but cannot represent perturbation-induced deformations. We introduce the Deformed Image Vortex Ansatz (DIVA): a perturbation-aware ansatz in which the response to an external perturbation is built into the magnetization profile itself, rather than appended to the dynamics as a correction. Here, we demonstrate the concept for a uniform, stationary in-plane field applied to a Permalloy nanodot, for which the deformation is analytically tractable. A symmetry-based perturbative expansion identifies the leading deformation as a single $m = 1$ harmonic around the disk, while energy minimization and a dominant-balance analysis yield a closed-form interpolant for the radial profile. Benchmarked against micromagnetic simulations on Permalloy disks of aspect ratio $t/R = 0.1$ and $0.0125$, this realization reduces the disk-averaged angular deviation by a factor of 3 to 6 relative to the two-vortex ansatz, depending on geometry and field, and reduces the total-energy deviation by about a factor of six in the thicker disk.
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All authors Thomas G. Coppée, Colin Ducarme, Simon de Wergifosse, Flavio Abreu Araujo

Plasma Physics

Control of Magnetic Reconnection in High Energy Density Plasmas

J. L. Latham, B. K. Russell, C. Dong et al. (+6 more)

Magnetic reconnection governs the explosive release of magnetic energy in systems from the solar corona to fusion plasmas, yet controlling it in the laboratory has remained out of reach. Here we demonstrate active control of reconnection in high-power laser-driven plasmas using a third, relativistic-intensity laser pulse that injects filaments of electron current into the reconnecting system. Two moderate-intensity lasers drive colliding magnetized plumes that reconnect, forming plasmoids in the current sheet as seen in proton deflectometry. The relativistic laser generates magnetic fields matching the polarity on either side of the layer, and, depending on its arrival time, either accelerates the breakup of the current sheet or suppresses reconnection. Arriving early, before the plumes strongly interact, it builds a pocket of magnetic pressure that repels them via flux pileup; arriving after the current sheet forms, it accelerates electrons that extend current filamentation instabilities into the upstream, causing rapid dissipation of the reconnecting magnetic field. This approach opens a route to steering magnetic energy flow in fusion plasmas and broadens the range of systems accessible to laboratory astrophysics.
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All authors J. L. Latham, B. K. Russell, C. Dong, C. A. Walsh, K. G. Miller, P. T. Campbell, L. Willingale, P. Nilson, K. Krushelnick

High Energy Physics (Theory)

Elliptic spin Ruijsenaars-Schneider integrable models from 5d $\mathcal{N}=1$ gauge theories

Gleb Arutyunov and Lukas Hardi

We show that the Coulomb branches of 5d $\mathcal{N}=1$ necklace quiver gauge theories on $\mathbb{R}^3 \times T^2$ are identified with the phase spaces of elliptic spin Ruijsenaars-Schneider models with dynamical inhomogeneities. This identification resolves the long-standing problem of determining a Poisson structure and a quantization of these models. We further show that the resulting quantum system is the integrable system governing supersymmetric indices of 4d $\mathcal{N}=1$ theories of class $\mathcal{S}_k$.
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Instrumentation and Methods for Astrophysics

Simulation tools for realistic high-order wavefront correction with the Roman Coronagraph

A. Lau, A. J. Riggs, S. F. Redmond et al. (+9 more)

The Roman Space Telescope Coronagraph Instrument (Roman CGI) will demonstrate high-contrast imaging from space using coronagraphic masks, deformable mirrors, and high-order wavefront sensing and control (HOWFSC). After the baseline technology demonstration, the Roman Coronagraph Community Participation Program (CPP) will pursue science and engineering studies that require realistic predictions of instrument behaviour, observing efficiency, and wavefront control performance. This paper describes corgihowfsc, a configurable simulation framework for repeatable Roman CGI HOWFSC studies. The framework preserves the Roman ground-in-the-loop (GITL) workflow represented by the NASA cgi-howfsc package, while allowing the images to be generated by the higher-fidelity corgisim model. In this configuration, cgi-howfsc remains the reference implementation for estimation, control, and compact-model Jacobian generation; corgisim can supply more flight-like images for studies of instrument performance and robustness. corgihowfsc also coordinates exposure planning, camera settings, expected iteration timing, and contrast normalisation of the HOWFSC loop through cgi-eetc, calibration-related workflows through cgi-coralign, structured diagnostics, and local or distributed execution. By exposing observing modes, image models, probe choices, estimators, controllers, deformable-mirror settings, and runtime options through reusable configuration files, corgihowfsc enables controlled comparisons between reference compact-model simulations and higher-fidelity HOWFSC studies.
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All authors A. Lau, A. J. Riggs, S. F. Redmond, E. Cady, J. Krist, I. Laginja, D. Sirbu, L. Delaye, R. Soummer, S. Noiret, J. C. Lambert, A. Bidot

Nuclear Theory

Symbolic Regression for Interpretable Emulation of Proton Collective Flow in Intermediate-Energy Heavy-Ion Collisions

Nicholas Cox, Xavier Grundler and Bao-An Li

Symbolic regression provides an interpretable machine-learning approach for constructing explicit analytic relations between physical inputs and observables. In this work, we develop symbolic-regression emulators for the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model and compare their performance with deep neural network (DNN) emulators. Using the same transport-model data employed in our previous emulator studies, we show that symbolic regression can reproduce the proton mid-rapidity slope $F_1$ of transverse flow $v_1$ and elliptic flow $v_2$ with accuracy comparable to that of DNNs, while providing explicit analytic expressions and substantially faster prediction once trained. We further demonstrate the use of symbolic regression in the reverse direction by constructing analytic relations that predict the in-medium nucleon-nucleon cross-section modification factor $X$ from the flow observables. Although the symbolic-regression models require substantially longer training times and exhibit greater run-to-run variation than DNNs, their analytic form and rapid evaluation make them promising tools for future transport-model sensitivity and uncertainty analyses.
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Fluid Dynamics

Towards Rapid Prototyping of Spray Injectors: A Regime-Agnostic Neural Operator Surrogate for Gas-Liquid Interface Evolution

Paolo Guida, Po-Han Chen, Hong G. Im et al. (+1 more)

Spray atomisation rapidly creates large liquid-gas interfacial areas and is central to many industrial processes. However, predicting spray behaviour and surface area remains difficult: experiments cannot access all spray regions, while CFD becomes prohibitively expensive as finer structures develop. Data driven surrogates can learn interface evolution, enabling rapid design space exploration, operating condition ranking, and ultimately spray control. We investigate how state representation, neural architecture, and physics-informed regularisation affect long horizon autoregressive forecasting of spray interfaces, particularly conservation. Our principal model is a boundary-conditioned Fourier Neural Operator (FNO) that predicts the evolution of the signed distance function (SDF) from the liquid-gas interface. It is trained on 2D sharp interface Volume-of-Fluid CFD simulations spanning several atomisation regimes. The SDF-FNO retains interface fidelity better than an FNO trained directly on volume fraction, but is outperformed by a U-Net. Objective function ablation shows that a liquid inventory penalty improves conservation at a modest cost to local interface accuracy. We also introduce a physics-informed extension combining an open-domain target-increment liquid balance penalty, a narrowband Eikonal regulariser that preserves signed distance geometry, and a phase-boundedness penalty. Although this model trains stably, it leaves forecast error, interface overlap, and inventory behaviour essentially unchanged relative to the data driven baseline. Finally, we demonstrate the surrogate by ranking injection conditions according to interfacial area generated per unit gas injection power across the operating envelope of a fixed geometry.
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All authors Paolo Guida, Po-Han Chen, Hong G. Im, William L. Roberts

Physics and Society

Spatially explicit feature importance for building height estimation using research-access high-resolution SAR and optical sensors

Guilherme Iablonovski, Pierre-Louis Frison and Tatiana Silva da Silva

Accurate building height information at the individual footprint scale is essential for material stock accounting and post-disaster damage assessments yet remains difficult to obtain at city scale in the Global South where airborne LiDAR coverage is rare and commercial very high-resolution imagery is cost-prohibitive or unavailable. While recent works have demonstrated building height estimation using freely available Sentinel imagery, the resolution ceiling of resulting products is still coarse for material stock analysis. This study incorporates products derived from data freely accessible under scientific research licenses, TerraSAR-X StripMap and PlanetScope, alongside Sentinel-1 to predict building heights in a large city in Brazil. To account for the spatial autocorrelation in the training set, features from all sources are integrated in a geographically weighted random forest model, returning an RMSE of 5.34 m and R2 of 0.756 against a LiDAR reference dataset. Local feature importance showed predictor dominance to vary consistently across intra-urban contexts, with footprint geometry dominating for low-rise buildings, shadow-derived height for taller and more isolated structures, and spectral reflectance for the tallest buildings in the set. Sentinel-1 backscatter and InSAR occupy complementary spatial niches, with no single sensor uniformly preferable across the set. Results provide optioneering guidance and insight over satellite-derived products predictive relevance in distinct contexts, which global machine learning or neural network models cannot offer.
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Accelerator Physics

Machine learning assisted Bayesian calibration of an accelerator digital twin from orbit response data

Christopher Kelly, Kevin A. Brown, Georg H. Hoffstaetter et al. (+2 more)

Digital twins of particle accelerators are used to plan and control operations and to design data collection campaigns. Accurate modeling typically requires knowledge of quantities that are hard to measure directly, e.g., magnet alignments, transfer functions relating power supply currents to magnetic fields, magnet nonlinearities, and stray fields. In this work we introduce multiplicative parameters to the quadrupole transfer functions to parametrize these effects. We use Bayesian methods to probabilistically estimate these parameters and their uncertainties by calibrating the Bmad digital twin to beam measurements performed at the AGS Booster at Brookhaven National Laboratory. The inference is computationally accelerated using a machine learning emulator of the physical accelerator digital twin trained to a perturbed-parameter ensemble of Bmad simulations. The result is a joint posterior distribution over the parameters constrained by the data, taking into account beam monitor errors. Incorporating estimates of the parameters into the digital twin is shown to result in a significant improvement in the quality of the model and provides error bars on the model parameters and predictions.
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All authors Christopher Kelly, Kevin A. Brown, Georg H. Hoffstaetter, Weijian Lin, Nathan M. Urban

Statistical Mechanics

Frustration without Glass: A Non-Abelian Gauge Model of Network Compatibility

Xuanhua Wang

We formulate a non-Abelian theory of network compatibility in which dynamical transformations reside on the links. Gauge covariance follows from the freedom to choose local representation frames, while plaquette holonomies quantify the incompatibility of closed-loop transformations. For an SU(2) model on the complete simplicial 2-complex with quenched random plaquette couplings, parallel-tempering simulations reveal a continuous disorder-driven phase transition characterized by the network compatibility $M_P$. As the disorder strength approaches the critical value, the compatibility drops rapidly to a value that decreases with system size, while the frustration energy of the network sharply rises. Moreover, analysis of connected replica-overlap width provides no evidence for thermodynamic replica-symmetry breaking. Instead, the high-disorder regime sustains a nearly constant integrated adjacent correlation as the system size increases. Therefore, rather than a frozen gauge glass or a featureless disordered “gas” phase, dense topological frustration produces a non-glassy correlated gauge liquid in which individual pair correlations are geometrically diluted while a finite integrated correlation survives.
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Optics

Robust Orbital Angular Momentum Transfer Using Low-Cost Diffractive Optics

Beatriz Morales-Cruzado, Benjamin Perez-Garcia, Francisco G. Peérez Gutiérrez et al. (+1 more)

Reliable transfer of orbital angular momentum (OAM) to microscopic objects typically relies on high-fidelity vortex beams generated by programmable spatial light modulators or precision-fabricated phase optics. Here, we demonstrate that robust OAM transfer in optical tweezers can be achieved using static binary holograms printed on acetate substrates. The printed diffractive optics generate Laguerre-Gaussian vortex beams with sufficient spatial fidelity to induce controlled optical torque and stable rotational manipulation of polystyrene microspheres in a high-numerical-aperture optical tweezers system. Despite a diffraction efficiency of only approximately 2%, the generated beams enable reproducible particle rotation using less than 1 mW of optical power in the first diffraction order. The rotational dynamics were systematically characterized as a function of incident optical power and topological charge, revealing the expected increase in angular velocity with both parameters, consistent with OAM-driven torque in the overdamped regime. These results demonstrate that efficient optical angular momentum transfer is remarkably tolerant to the reduced efficiency of passive printed diffractive optics, establishing a robust, scalable, and high-damage-threshold platform for structured-light optical manipulation with applications in microfluidics, biophysics, optomechanics, and optical trapping.
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All authors Beatriz Morales-Cruzado, Benjamin Perez-Garcia, Francisco G. Peérez Gutiérrez, Carmelo Rosales-Guzmán

Materials Science

Electron transport in amorphous materials: from localization to predictive transport modeling

Yeonghun Lee

Amorphous materials are disordered solids without long-range structural order, making them useful systems for studying electron transport beyond the crystalline picture. This review discusses how structural disorder changes the spatial character of electron wavefunctions and how these changes govern carrier transport in amorphous materials, especially amorphous semiconductors. Basic concepts of Anderson localization, mobility edges, diffusive transport, and hopping transport are first reviewed, followed by representative amorphous semiconductors, including amorphous silicon and amorphous oxide semiconductors. Computational approaches are then discussed, from conventional Boltzmann and Green's-function-based transport theories to real-space Kubo-Greenwood simulations combined with molecular dynamics. The discussion focuses on localization, spectral broadening, finite-temperature lattice fluctuations, and electron-phonon interactions. Recent progress and remaining issues in predictive transport modeling of amorphous materials are then outlined.
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Nuclear Theory

Data-Driven Statistical Ensembles of Chiral Nuclear Interactions

Pengsheng Wen and Jeremy W. Holt

Recent advances in ab initio nuclear theory, machine learning, and Bayesian inference, coupled with increasingly precise nuclear experiments and astrophysical observations, have enabled more robust constraints on fundamental descriptions of the nuclear interaction. Although well-established nonlinear regression methods can identify best-fit sets of low-energy constants at fixed resolution scale, they provide limited insight into the full underlying probability distributions of those constants. A central remaining challenge in nuclear theory is therefore to characterize full probability distributions of nuclear forces across resolution scales. In this work, we employ normalizing flows, a class of expressive generative machine learning models, to infer the joint probability distribution of two-body low-energy constants (LECs) in chiral effective field theory over a wide range of resolution scales. The resulting LEC distributions are shown to accurately reproduce experimental neutron-proton scattering phase-shift distributions. Furthermore, strong non-Gaussian correlations among LECs are revealed, indicating a nontrivial interplay among distinct short-range nuclear dynamics. This work establishes a general framework for constructing statistical ensembles of nuclear interactions that can be systematically constrained by future nuclear experiments and astrophysical observations.
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Atomic Physics

Optically Writable Atomic Vapor Memory as a Substrate for Optical Reservoir Computing

Elizabeth Robertson, Mingwei Yang, Lina Jaurigue et al. (+3 more)

We present an optical random access memory (ORAM) based on warm cesium (Cs) atomic vapor and demonstrate its operation as the physical substrate of a reservoir computer. Information is stored in the hyperfine population distribution of a Cs ensemble via optical pumping and retrieved through differential probe absorption. Spatial multiplexing via acousto-optic deflection provides eight addressable memory rails able to store up to 3.8 bits of information per rail. Employing this platform as a temporally multiplexed reservoir, we achieve a kernel rank ($\mathrm{KR}= 8.8 \pm 0.4$), and a minimum bit error rate of $0.02 \pm 0.01$ on the Exclusive-or (XOR) benchmark. We find the limited memory lifetime constrains the achievable temporal depth, encouraging further research into fast addressable memories. This constitutes the first demonstration of a free-space, optically writable atomic RAM as a substrate in an optical reservoir computing system.
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All authors Elizabeth Robertson, Mingwei Yang, Lina Jaurigue, Guillermo Gallego, Kathy Lüdge, Janik Wolters

High Energy Astrophysical Phenomena

The high entropy of the UHECR arrival direction distribution favors a light composition

Nimrod Strasman and Eli Waxman

We analyze the constraints on the composition of ultra-high-energy cosmic rays (UHECRs), and on the density and distribution of their sources, that may be inferred from their arrival-direction distribution, using a novel semi-analytical description of the propagation energy loss of atomic nuclei ($A>4$) with energy $>2\times10^{19}~\text{eV}$, that allows generating UHECR arrival maps faster than by using detailed propagation simulations and yields insights to the impact of propagation energy loss. We show that the anisotropy of the UHECR arrival direction distribution due to the large-scale structure (LSS) of matter distribution is larger for heavy nuclei composition compared to protons, despite their larger deflections by magnetic fields, due to their shorter propagation distance and weaker dependence of rigidity on observed energy. Identifying the LSS anisotropy signal is hampered for heavy nuclei due to their large deflections by the uncertain Galactic magnetic field (GMF). We introduce a new measure of anisotropy, an "entropy" of the arrival-direction distribution, that is largely independent of the GMF configuration and has strong discriminating power between heavy- and light-composition models. Analyzing the public $>3.2\times10^{19}$~eV Auger data, we show that the correlation with the LSS on large angular scales is weak and requires a low source density, $s_0\le10^{-4}{\rm Mpc}^{-3}$, to allow masking the LSS signature by "cosmic-variance" ($s_0=10^{-2}{\rm Mpc}^{-3}$ is ruled out at $>99\%$ confidence level (CL)). The high entropy of the distribution is consistent with proton models and inconsistent with heavy nuclei models at $>96\%$ CL for $s_0\ge10^{-5}{\rm Mpc}^{-3}$. Reducing the absolute energy calibration uncertainty may allow detection of the LSS correlation for proton models (increased exposure alone will not suffice due to the dominance of cosmic variance).
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Quantum Physics

Pulsed to continuous-wave quantum dot cavity-QED

Mio Poortvliet, Petr Steindl and Wolfgang Löffler

Resonant cavity-quantum system interactions are well understood in the pulsed coherent and continuous-wave steady-state limits, but not much in between. We investigate the intermediate regime, where pulse duration, coupling, decoherences, and decays occur on comparable timescales, and pulse bandwidth matches cavity splitting and detunings. We reveal an interplay of cavity-enhanced excitation and Purcell-enhanced emission leading to warped chevron patterns. We develop a quantum master-equation model that efficiently treats the excitation-light coherent states in photon number space and reproduces the experimental data. Using these results we identify how polarization-split cavities can optimize single-photon purity and emission probability.
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Quantum Physics

Interference Engineering for Quantum Imaginary-Time Evolution through Multiple Energy Shifts

Hong-Jian Tang and Dan-Bo Zhang

Energy shifting is usually trivial in imaginary-time evolution because it changes only the normalization of the evolved state. On a quantum computer, however, imaginary-time evolution can be implemented as a coherent or sampled superposition of real-time evolutions, in which energy shifts generate relative phases that can interfere. Here we introduce multi-shift quantum imaginary-time evolution (MS-QITE), which uses a distribution of energy shifts to engineer this interference and optimize different implementations. In a Monte Carlo realization, multi-shift reshapes the normalized sampling distribution and concentrates it within a shorter real-time window, thereby reducing the typical Hamiltonian-evolution time and improving the stability of ground-state-energy estimation. In a continuous-variable-assisted realization, it enables projection onto a state supported over a finite quadrature interval, substantially reducing the required squeezing over an intermediate temperature range while retaining accurate thermal-state preparation. Numerical results for transverse-field Ising models demonstrate that energy shifts provide an interference-based degree of freedom for optimizing quantum imaginary-time evolution.
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Mesoscale and Nanoscale Physics

Observation of magnetic quantum phase crossovers in a semiconductor spin ladder

Elizaveta Morozova, Xin Zhang, Utso Bhattacharya et al. (+9 more)

Understanding collective phases of strongly correlated quantum magnets relies on theoretically tractable model systems with precise microscopic control. Antiferromagnetic spin ladders provide such a setting, hosting field-tunable gapped and gapless phases at half filling and unconventional pairing tendencies upon doping. Here, we realize a programmable Heisenberg spin ladder in a half-filled germanium quantum dot array featuring site-resolved, continuously tunable exchange interactions. Under a fixed magnetic field, we vary the rung and leg coupling to map the rung-singlet, canted antiferromagnetic, and fully polarized phases. Hamiltonian-learning protocols combining equilibrium and dynamical measurements quantitatively characterize the ladder, incorporating spin-orbit interactions to reproduce the observed crossover behavior. Measurements of higher-order spin correlators – including four-point correlations inaccessible to conventional bulk probes – reveal signatures of the underlying phase structure despite the finite size. Our results establish germanium quantum dot arrays as a controllable platform for quantum magnetism, opening routes to investigate unconventional superconductivity in doped ladders.
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All authors Elizaveta Morozova, Xin Zhang, Utso Bhattacharya, Pablo Cova Fariña, Daniel Jirovec, Alexander Nico-Katz, Stefan D. Oosterhout, Sougato Bose, Giordano Scappucci, Menno Veldhorst, Eugene Demler, Lieven M. K. Vandersypen

Materials Science

Defect Geometry Selects Polar and Anomalous Hall Phases in Two-Dimensional Altermagnets

Xujia Gong, Amar Fakhredine, Hosein Alavi-Rad et al. (+6 more)

Point defects in altermagnets can create phases absent in the pristine host by selectively breaking crystal symmetries. Combining symmetry analysis, first-principles calculations, and Hamiltonian modeling, we identify how point impurities modify the altermagnetic phase. Using the pristine d- wave altermagnetic monolayer V2Se2O as a testbed, we identify three distinct classes of impurities: those that preserve spin-momentum locking, those that induce a hybrid-parity state associated with Edelstein spin conversion, and those that produce a metallic ferrimagnetic state with an anomalous Hall effect. We further discuss the robustness of two-dimensional altermagnets against point impurities. Results for other two-dimensional systems, such as Mn4N2 and 2H-FeBr3, reveal the same symmetry-based control across distinct lattices and parent spin harmonics, establishing defect geometry as a general route for engineering spin textures and transport properties.
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All authors Xujia Gong, Amar Fakhredine, Hosein Alavi-Rad, Mahyar Hassani-Vasmejani, Xing Ming, Xiangang Wan, Carmine Autieri, Meysam Bagheri Tagani, Sahar Izadi Vishkayi

Materials Science

Polarization-Dependent Raman Selection Rules in Sb$_2$S$_3$ from First Principles and Experiment

Tobias Dierke, Michael Hüttenkofer, Stefan Wolff et al. (+4 more)

Antimony sulfide (Sb$_2$S$_3$) is a semiconductor composed of quasi-one-dimensional ribbon-like structural units, which give rise to pronounced structural anisotropy in the bulk crystal. Despite growing interest in Sb$_2$S$_3$, in particular Sb$_2$S$_3$ thin films, a detailed understanding of its symmetry-based lattice dynamics remains incomplete. Here, we present a combined experimental and theoretical study of polarization-dependent Raman scattering in Sb$_2$S$_3$ thin films. We derive the Raman selection rules from the crystal symmetry and calculate the zone-center phonon modes and corresponding Raman tensors using density functional theory. The calculated polarization dependencies are systematically compared with polarization-dependent Raman measurements performed on oriented crystalline domains of Sb$_2$S$_3$ thin films. This combined analysis enables reliable mode assignments, elucidates the anisotropic Raman response associated with the ribbon-like crystal structure, and demonstrates the sensitivity of polarized Raman spectroscopy to crystal orientation and structural order in antimony chalcogenide (Sb$_2$S$_3$, Sb$_2$Se$_3$) as well as isostructural Bi$_2$S$_3$ thin films.
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All authors Tobias Dierke, Michael Hüttenkofer, Stefan Wolff, Mingjian Wu, Julien Bachmann, Erdmann Spiecker, Janina Maultzsch