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PRODID:-//Nonequilibrium Quantum Workshop NQW - ECPv6.14.2//NONSGML v1.0//EN
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X-WR-CALNAME:Nonequilibrium Quantum Workshop NQW
X-ORIGINAL-URL:https://nqw.ijs.si
X-WR-CALDESC:Events for Nonequilibrium Quantum Workshop NQW
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Europe/Ljubljana
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TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20230326T010000
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BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20231029T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T120000
DTEND;TZID=Europe/Ljubljana:20231210T160000
DTSTAMP:20260406T064055
CREATED:20231202T210059Z
LAST-MODIFIED:20231207T151217Z
UID:3048-1702209600-1702224000@nqw.ijs.si
SUMMARY:Registration
DESCRIPTION:
URL:https://nqw.ijs.si/event/registration-2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T160000
DTEND;TZID=Europe/Ljubljana:20231210T161500
DTSTAMP:20260406T064055
CREATED:20231201T190117Z
LAST-MODIFIED:20231207T151218Z
UID:2542-1702224000-1702224900@nqw.ijs.si
SUMMARY:NQW: Opening
DESCRIPTION:
URL:https://nqw.ijs.si/event/nqw-opening/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T161400
DTEND;TZID=Europe/Ljubljana:20231210T180000
DTSTAMP:20260406T064055
CREATED:20231207T151218Z
LAST-MODIFIED:20231207T151242Z
UID:3104-1702224840-1702231200@nqw.ijs.si
SUMMARY:Chair: Jaka Vodeb
DESCRIPTION:
URL:https://nqw.ijs.si/event/chair-jaka-vodeb-2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T161500
DTEND;TZID=Europe/Ljubljana:20231210T164500
DTSTAMP:20260406T064055
CREATED:20231130T151051Z
LAST-MODIFIED:20231207T151218Z
UID:2536-1702224900-1702226700@nqw.ijs.si
SUMMARY:Robin Steinigeweg: Constructing nonequilibrium steady states ‌from equilibrium correlation functions
DESCRIPTION:R. Steinigeweg1 \n1University of Osnabrück\, Department of Mathematics/Computer Science/Physics\, Barbarastr. 7\, D-49076 Osnabrück\, Germany \nState-of-the-art approaches to extract transport coefficients of many-body quantum systems broadly fall into two categories: (i) they target the linear-response regime in terms of equilibrium correlation functions of the closed system; or (ii) they consider an open-system situation typically modeled by a Lindblad equation\, where a nonequilibrium steady state emerges from driving the system at its boundaries. While quantitative agreement between (i) and (ii) has been found for selected model and parameter choices\, also disagreement has been pointed out in the literature. Studying magnetization transport in the spin-1/2 XXZ chain\, we here demonstrate that at weak driving the nonequilibrium steady state in an open system\, including its buildup in time\, can remarkably be constructed just on the basis of correlation functions in the closed system. We numerically illustrate this direct correspondence of closed-system and open-system dynamics\, and show that it allows the treatment of comparatively large open systems\, usually only accessible to matrix product state simulations. We also point out potential pitfalls when extracting transport coefficients from nonequilibrium steady states in finite systems. \n\nT. Heitmann et al. arXiv:2303.00430\nT. Heitmann et al. Physical Review E 108\, 024102 (2023)
URL:https://nqw.ijs.si/event/robin-steinigeweg-constructing-nonequilibrium-steady-states-from-equilibrium-correlation-functions/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T164500
DTEND;TZID=Europe/Ljubljana:20231210T171500
DTSTAMP:20260406T064055
CREATED:20231201T190118Z
LAST-MODIFIED:20231207T151218Z
UID:2545-1702226700-1702228500@nqw.ijs.si
SUMMARY:Rok Zitko: Richardson model description of spin-orbit coupling ‌in superconducting islands
DESCRIPTION:R. Žitko1\,2\, L. Pavešič1\,2 \n1Jožef Stefan Institute\, Jamova 39\, Ljubljana\, Slovenia \n2Faculty of mathematics and physics\, Jadranska 19\, Ljubljana\, Slovenia \nRichardson model\, first introduced in nuclear physics as a simplified model of nucleon pairing\, is also an appropriate description of a small superconducting island with fixed charge. Complex systems composed of interconnected superconducting islands and interacting quantum dots can be modelled using Hamiltonians that can be transformed into the matrix-product-operator form with small matrices that can be efficiently solved using the density matrix renormalization group [1\,2]. This approach allows to include without any approximations the effects of both the exchange interaction (Kondo screening and Yu-Shina-Rusinov subgap states) and the charge repulsion (Coulomb blockade\, capacitive coupling) [3] and thereby provide reference results for this family of Hamiltonians that are more general than regular quantum impurity problems. The theory results match well the experimental measurements on hybrid semi-super devices [3\,4]. \nI will describe how this approach can be extended to incorporate two further phenomena\, the spin-orbit coupling and the proximity effect leading to level-dependent pairing strength [5]. The combination of the two leads to a degeneracy of even and odd-parity ground states in the regime where the external magnetic field becomes strong enough to generate an increasing number of quasiparticles in the superconducting levels with the weakest pairing strength. This manifests as equal spacing of even and odd states in the charge stability diagrams. \n\nLuka Pavešič\, Daniel Bauernfeind\, and Rok Žitko\, Phys. Rev. B 104\, L241409 (2021)\nLuka Pavešič and Rok Žitko\, Phys. Rev. B 105\, 075129 (2022)\nJuan Carlos Estrada Saldaña\, Alexandros Vekris\, Luka Pavešič\, Peter Krogstrup\, Rok Žitko\, Kasper Grove-Rasmussen & Jesper Nygård\, Nat. Commun. 13\, 2243 (2022)\nJuan Carlos Estrada Saldaña\, Alexandros Vekris\, Luka Pavešič\, Rok Žitko\, Kasper Grove-Rasmussen\, Jesper Nygård\, arXiv:2203.00104\nJuan Carlos Estrada Saldaña\, Luka Pavešič\, Alexandros Vekris\, Kasper Grove-Rasmussen\, Jesper Nygård\, Rok Žitko\, arXiv:2306.06001
URL:https://nqw.ijs.si/event/rok-zitko-richardson-model-description-of-spin-orbit-coupling-in-superconducting-islands/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T171500
DTEND;TZID=Europe/Ljubljana:20231210T174500
DTSTAMP:20260406T064055
CREATED:20231201T190118Z
LAST-MODIFIED:20231207T151220Z
UID:2546-1702228500-1702230300@nqw.ijs.si
SUMMARY:Simon Gerber: Direct characterization of photo- and electrically-induced‌ “hidden” state switching of 1T-TaS2
DESCRIPTION:S. Gerber1 \n1Laboratory for X-ray Nanoscience and Technologies\, Paul Scherrer Institut\, CH-5232 Villigen PSI\, Switzerland \nBrilliant\, ultrashort\, and coherent X-ray free-electron laser (FEL) pulses allow for investigation of dynamics at the inherent time and length scale of atoms. I will illustrate this capability at the example of recent time-resolved X-ray diffraction data taken in the “hidden” phase of the Van der Waals material 1T-TaS2\, hinting that out-of-plane restacking suppresses the optically-induced hidden state. Furthermore\, I will also present preliminary static micro-beam X-ray diffraction data of electrically switched 1T-TaS2 cryomemory cells which indicate that also from a structural point of view the photo- and electrically-induced “hidden” states are closely related.
URL:https://nqw.ijs.si/event/simon-gerber-direct-characterization-of-photo-and-electrically-induced-hidden-state-switching-of-1t-tas2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T174500
DTEND;TZID=Europe/Ljubljana:20231210T180000
DTSTAMP:20260406T064055
CREATED:20231201T190119Z
LAST-MODIFIED:20231207T151220Z
UID:2547-1702230300-1702231200@nqw.ijs.si
SUMMARY:Corinna Burri: Spatial mapping of the electronic structure of 1T-TaS2
DESCRIPTION:C. Burri\,1\,2 S. Ekahana\,1 R. Venturini\,3 E. Della Valle\,1 M. Muntwiler\,1 V. Strokov\,1 A. Barinov\,4 G. Aeppli\,1\,2\,5 Y. Ekinci\,1 D. Mihailovic\,3 S. Gerber1 \n1Photon Science Division\, Paul Scherrer Institut\, Villigen PSI\, Switzerland \n2Department of Physics and Quantum Center\, ETH Zurich\, Zurich\, Switzerland \n3Department of Complex Matter\, Institut Jožef Stefan\, Ljubljana\, Slovenia \n4Elettra-Sincrotrone Trieste ScPA\, Trieste\, Italy \n5Institut de Physique\, EPFL\, Lausanne\, Switzerland \nAs a step towards resolving the spatially-resolved electronic structure of the layered transition metal dichalcogenide 1T-TaS2 – and eventually electronically switched cryomemory devices – we have performed angle-resolved photoemission spectroscopy (ARPES). Using a photon energy of 72 eV and the micrometer spot size available at the spectromicroscopy beamline of the Elettra synchrotron\, we measured the band structure and high-statistics Fermi surface of 11\, 500 and 600 nm thick flakes. Also\, the first-order phase transition from the nearly-commensurate to the commensurate CDW state leads to a prominent splitting of the Ta 4f core levels which we have mapped spatially. In addition\, using 400 eV soft X-ray ARPES at the ADRESS beamline of the Swiss Light Source synchrotron\, we established the kz dependence of the band structure of a 110-nm thick flake\, which reveals a two dimensionality of the electronic structure.
URL:https://nqw.ijs.si/event/corinna-burri-spatial-mapping-of-the-electronic-structure-of-1t-tas2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T180000
DTEND;TZID=Europe/Ljubljana:20231210T193000
DTSTAMP:20260406T064055
CREATED:20231201T195036Z
LAST-MODIFIED:20231207T151220Z
UID:2746-1702231200-1702236600@nqw.ijs.si
SUMMARY:Dinner
DESCRIPTION:
URL:https://nqw.ijs.si/event/dinner-5/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T192900
DTEND;TZID=Europe/Ljubljana:20231210T210000
DTSTAMP:20260406T064055
CREATED:20231207T151220Z
LAST-MODIFIED:20231207T151248Z
UID:3107-1702236540-1702242000@nqw.ijs.si
SUMMARY:Chair: Tomaz Mertelj
DESCRIPTION:
URL:https://nqw.ijs.si/event/chair-tomaz-mertelj/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T193000
DTEND;TZID=Europe/Ljubljana:20231210T200000
DTSTAMP:20260406T064055
CREATED:20231201T190119Z
LAST-MODIFIED:20231207T151220Z
UID:2549-1702236600-1702238400@nqw.ijs.si
SUMMARY:Patrycja Łydżba: Integrals of motion in dipole-conserving models
DESCRIPTION:P. Łydżba\,1 P. Prelovšek\,1 M. Mierzejewski2 \n1Institute of Theoretical Physics\, Wroclaw University of Science and Technology\, 50-370 Wroclaw\, Poland \n2Department of Theoretical Physics\, J. Stefan Institute\, SI-1000 Ljubljana\, Slovenia \nThe Hilbert space fragmentation\, for which the Hamiltonian shatters into exponentially many blocks in the site occupation basis\, can result in the breakdown of thermalization. In this presentation\, we focus on the pair-hopping (PH) model\, a paradigmatic model of the Hilbert-space fragmentation. Furthermore\, it can be derived as an effective model of the Stark chain\, imposing strict conservation of the dipole moment. Notably\, the non-vanishing autocorrelation functions in the PH model\, as reported in [1]\, suggests the existence of local or quasilocal integrals of motion (IOMs). Hence\, we propose a numerical algorithm that establishes all IOMs linear in a given set of operators. We employ it to demonstrate that the density modes in the PH model are frozen and become strict IOMs in the thermodynanic limit. Nevertheless\, these modes become subdiffusive after incorporating higher-order corrections the PH model. Finally\, we make a connection with the Stark model. We demonstrate that although both energy and dipole moment are conserved in the thermodynamic limit [2]\, the Stark chain supports only one IOM. \n\nP. Sala et al.\, Physical Review X 10 (2020)\nS. Nandy et al.\, arXiv:2310.01862 (2023)
URL:https://nqw.ijs.si/event/patrycja-lydzba-integrals-of-motion-in-dipole-conserving-models/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T200000
DTEND;TZID=Europe/Ljubljana:20231210T201500
DTSTAMP:20260406T064055
CREATED:20231201T190119Z
LAST-MODIFIED:20231207T151236Z
UID:2550-1702238400-1702239300@nqw.ijs.si
SUMMARY:Miroslav Hopjan: Critical quantum dynamics of observables at eigenstate transitions
DESCRIPTION:S. Jiricek\,1 M. Hopjan\,2 P. Łydżba\,3 F. Heidrich-Meisner\,1 L. Vidmar2\,4 \n1Institut für Theoretische Physik\, Georg-August-Universität Goettingen\, D-37077 Goettingen\, Germany \n2Department of Theoretical Physics\, J. Stefan Institute\, SI-1000 Ljubljana\, Slovenia \n3Department of Theoretical Physics\, Wroclaw University of Science and Technology\, 50-370 Wroclaw\, Poland \n4Department of Physics\, Faculty of Mathematics and Physics\, University of Ljubljana\, SI-1000 Ljubljana\, Slovenia \nIt is an outstanding goal to unveil the fingerprints of universal quantum dynamics at eigenstate transitions. Focusing on quadratic fermionic Hamiltonians\, we identify physical observables that exhibit critical behavior at the transition. Our result is based on two ingredients: (a) A relationship between the observable time evolution in a many-body state and the transition probabilities in single-particle states\, and (b) a scale invariance of transition probabilities\, which generalizes the recent result for survival probabilities [1\,2]. We then show that these properties give rise to a critical behavior in the quantum quench dynamics of observables\, which share the common eigenbasis with the Hamiltonian before the quench. We numerically demonstrate this phenomenon at the localization transition in the three-dimensional Anderson model\, for which the critical bahavior can be detected in experimentally relevant observables such as site occupations and particle imbalance [3]. \n\nM. Hopjan and L.Vidmar\, Phys. Rev. Lett. 131\, 060404 (2023)\nM. Hopjan and L.Vidmar\, arXiv:2309.16005 (2023)\nS. Jiricek et al.\, in preparation
URL:https://nqw.ijs.si/event/miroslav-hopjan-critical-quantum-dynamics-of-observables-at-eigenstate-transitions/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T201500
DTEND;TZID=Europe/Ljubljana:20231210T203000
DTSTAMP:20260406T064055
CREATED:20231201T190119Z
LAST-MODIFIED:20231207T151236Z
UID:2551-1702239300-1702240200@nqw.ijs.si
SUMMARY:Hui Zhao: Laser-induced tunnel ionization ‌and femtosecond nonthermal melting in MgO
DESCRIPTION:H. Zhao1 \n1Jozef Stefan Institute\, Ljubljana\, Slovenia \nLaser-induced melting plays a crucial role in advancing manufacturing technology and ultrafast science [1-3]; however\, its atomic processes and microscopic mechanisms remain elusive due to complex interplays between many degrees of freedom within a timescale of ~100 femtoseconds. We employ MgO as an example to investigate the nonequilibrium mechanisms of laser-driven ultrafast nonthermal melting of wide-gap materials. Our study is based on real-time time-dependent density functional theory (rt-TDDFT) molecular dynamics (MD) simulations. We report here that laser melting is greatly accelerated by tunnel ionization processes. The tunneling processes generate a large number of photocarriers and results in intense energy absorption\, instantaneously changing the potential energy surface of lattice configuration. The strong electron-phonon couplings and fast carrier relaxation enable the efficient energy transfer between electrons and the lattice. The modulation of melting thresholds and phase boundary demonstrate the possibility of manipulating phase transition on demand. A shock wave curve is also obtained at moderate conditions (P < 50 GPa)\, extending Hugoniot curve to new regimes. These results account well for the latest ultrafast melting experiments\, and provide atomistic details and nonequilibrium mechanism of photoinduced ultrafast phase transitions in wide-gap materials. \n\nS. K. Sundaram et al.\, Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses. Nat. Mater. 1\, 217-224 (2002)\nC. W. Siders et al.\, Detection of nonthermal melting by ultrafast X-ray diffraction. Science 286\, 1340-1342 (1999)\nE. H. Penilla et al.\, Ultrafast laser welding of ceramics. Science 365\, 803-808 (2019)
URL:https://nqw.ijs.si/event/hui-zhao-laser-induced-tunnel-ionization-and-femtosecond-nonthermal-melting-in-mgo/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T203000
DTEND;TZID=Europe/Ljubljana:20231210T204500
DTSTAMP:20260406T064055
CREATED:20231201T190135Z
LAST-MODIFIED:20231207T151236Z
UID:2557-1702240200-1702241100@nqw.ijs.si
SUMMARY:Rok Venturini: Nanoscale polytype heterostructures
DESCRIPTION:R. Venturini\,1 Y. Vaskivskyi\,1\,2 Q. Hu\,1 P. Aupič\,1\,2 D. Mihailović1\,3 \n1Jožef Stefan Institute\, Jamova 39\, SI-1000 Ljubljana\, Slovenia \n2Faculty of Mathematics and Physics\, University of Ljubljana\, Jadranska 19\, Ljubljana\, Slovenia \n3CENN Nanocenter\, Jamova 39\, Ljubljana\, Slovenia \nThe transitional metal dichalcogenides crystalize in different polytypes\, dictating their charge density wave (CDW) states. It is possible to perform the polytype transformation in situ by either an optical [1] or an electrical pulse [2\,3]\, creating new nanoscale structures and polytypes that sometimes do not exist as bulk materials. We explore the polytype transformed structures of bulk materials 2H-NbSe2 and 4Hb-TaSe2. \nUsing the electrical pulse from the STM tip\, the surface of the 2H-NbSe2 is transformed to the 1T polytype in which we observe rich CDW physics of domains and domain walls\, as well as dynamical switching between different charge ordering configurations. The diverse spectroscopic signature of the CDW state shows a similarity to the hidden state of 1T-TaS2 [4]. \nWe also present experiments on 4Hb-TaSe2 which consists of alternating stacking of the 1T and 1H layers. Similar to the 2H-NbSe2 experiments\, we show that it is possible to create a nanoscale polytype transformation of the top surface from the 1H to the 1T polytype with the electrical pulse from the STM tip. Although the transformed 1T polytype in both materials adopts the same √13×√13 CDW superlattice\, their electronic structure is different. Other materials from the group of 2H and 4Hb polytypes could likely be explored for nanoscale polytype transformations.  \n\nJ. Ravnik et al. ACS Appl Nano Mater. 2\, 3743 (2019)\nJ. Zhang et al. Science 274\, 757 (1996)\nF. Bischoff et al. Chem. Mater. 29\, 9907 (2017)\nD. Cho et al. Nat. Commun. 7\, 10453 (2016)
URL:https://nqw.ijs.si/event/rok-venturini-nanoscale-polytype-heterostructures/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231210T204500
DTEND;TZID=Europe/Ljubljana:20231210T210000
DTSTAMP:20260406T064055
CREATED:20231201T190135Z
LAST-MODIFIED:20231207T151236Z
UID:2558-1702241100-1702242000@nqw.ijs.si
SUMMARY:Yevhenii Vaskivskyi: Electronic Amorphous State of 1T-TaS2: ‌An Order Embedded in the Disorder
DESCRIPTION:Y. Vaskivskyi\,1\,2 P. Aupic\,2 J. Vodeb\,1 Q. Hu\,1 F. Scepanovic\,2 D. Mihailovic1\,2\,3 \n1Department of Complex Matter\, Jozef Stefan Institute\, Jamova 39\, SI-1000 Ljubljana\, Slovenia \n2Faculty of Mathematics and Physics\, University of Ljubljana\, SI-1000 Ljubljana\, Slovenia \n3CENN Nanocenter\, Jamova 39\, SI-1000 Ljubljana\, Slovenia \nThe 1T-TaS2\, a peculiar transition metal dichalcogenide with a charge density wave (CDW) at low temperatures\, has been studied for the last 10 years since the original discovery of a metastable hidden (H) state in it [1]. Mainly\, the research was focused on the properties of this state [2] as well as their possible applications [3]. The H-state can be achieved by driving the material out of equilibrium using an ultrashort laser pulse or a short electrical pulse. Similarly to the H-state\, at higher excitation fluences an electronic amorphous (A) state can be reached. \nIn our scanning tunnelling microscopy studies\, we are exploring the coexistence of amorphous\, commensurate (C) and hidden CDWs; and the dynamical reconfigurations between them. At the same time\, we are showing that in addition to these CDWs\, the A-state can locally form embedded `islands` of charge order not observed in any other states of the material. In addition\, studies of the dynamics in the A-state are showing possible transitions as well as thermal fluctuations of this ordering. \nThe observed local behaviour of this system with various emergent states is a good example of topologically-constrained dynamics. As a result\, the A-state of 1T-TaS2 provides valuable insight into the correlation between topology and kinetics in many-body quantum states and can be considered an accessible experimental model for studying non-equilibrium quantum dynamics. \n \nFig. 1. A-state of 1T-TaS2 measured with STM with a high (a) and normal (c) CDW density. a\, c) Positions of the CDW peaks (points) and corresponding Voronoi tessellations (filled polygons). The colourmap is defined by Na/p – the number of atomic positions occupied by a single peak of CDW with red corresponding to the most dense CDW order. Na/p=13 corresponds to the commensurate CDW in 1T-TaS2. b\, d) Original STM images showing the border between the A and the H states. \n\nL. Stojchevska et al. Science 344\, 177–180 (2014)\nI. Vaskivskyi et al. Sci. Advances 1\, e1500168 (2015)\nA. Mraz et al. Nano Lett. 22\, 4814-4821 (2022)
URL:https://nqw.ijs.si/event/yevhenii-vaskivskyi-electronic-amorphous-state-of-1t-tas2-an-order-embedded-in-the-disorder/
CATEGORIES:NQW 2023
END:VEVENT
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