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PRODID:-//Nonequilibrium Quantum Workshop NQW - ECPv6.14.2//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
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
BEGIN:DAYLIGHT
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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END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T085900
DTEND;TZID=Europe/Ljubljana:20231214T101500
DTSTAMP:20260507T120305
CREATED:20231207T151601Z
LAST-MODIFIED:20231207T151638Z
UID:3153-1702544340-1702548900@nqw.ijs.si
SUMMARY:Chair: Lev Vidmar
DESCRIPTION:
URL:https://nqw.ijs.si/event/chair-lev-vidmar-2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T090000
DTEND;TZID=Europe/Ljubljana:20231214T093000
DTSTAMP:20260507T120305
CREATED:20231201T190420Z
LAST-MODIFIED:20231207T151601Z
UID:2614-1702544400-1702546200@nqw.ijs.si
SUMMARY:Andrew George Green: Phase Transitions in the Classical Simulability of Open Quantum Systems
DESCRIPTION:A.G. Green1 \n1University College London\, UK \nWe introduce a Langevin unravelling of the density matrix evolution of an open quantum system over matrix product states\, which we term the time-dependent variational principle-Langevin equation. This allows the study of entanglement dynamics as a function of both temperature and coupling to the environment. As the strength of coupling to and temperature of the environment is increased\, we find a transition where the entanglement of the individual trajectories saturates\, permitting a classical simulation of the system for all times. This is the Hamiltonian open system counterpart of the saturation in entanglement found in random circuits with projective or weak measurements. If a system is open\, there is a limit to the advantage in simulating its behaviour on a quantum computer\, even when that evolution harbours important quantum effects. Moreover\, if a quantum simulator is in this phase\, it cannot simulate with quantum advantage.
URL:https://nqw.ijs.si/event/andrew-george-green-phase-transitions-in-the-classical-simulability-of-open-quantum-systems/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T093000
DTEND;TZID=Europe/Ljubljana:20231214T100000
DTSTAMP:20260507T120305
CREATED:20231201T190420Z
LAST-MODIFIED:20231207T151601Z
UID:2615-1702546200-1702548000@nqw.ijs.si
SUMMARY:Till Domröse: Light-induced hexatic state observed by ultrafast nanobeam diffraction
DESCRIPTION:T. Domröse\,1 Th. Danz\,1 S.F. Schaible\,2 K. Rossnagel\,3\,4 S.Y. Yalunin\,1 C. Ropers1\,2 \n1Max Planck Institute for Multidisciplinary Sciences\, Göttingen\, Germany \n24th Physical Institute – Solids and Nanostructures\, University of Göttingen\, Germany \n3Institute of Experimental and Applied Physics\, Kiel University\, Germany \n4Ruprecht Haensel Laboratory\, Deutsches Elektronen-Synchrotron DESY\, Germany \nQuantum materials are characterised by enhanced correlations between their microscopic degrees of freedom that favor the occurence of exciting physical properties that are tunable by optical excitation\, including the formation of charge-density waves (CDWs). The investigation of the dynamics following such an optical quench is available in ultrafast transmission electron microscopes (UTEMs)\, versatile tools that combine nanometer spatial with femtosecond temporal resolution (Fig. 1a) [1\,2]. \nHere\, we investigate the transformation between the nearly-commensurate (NC) and the incommensurate (IC) CDW phase in the layered quantum material 1T-TaS2 [3\,4]. Therein\, selective contrast enhancement by means of ultrafast dark-field microscopy allows us to follow the spatially heterogeneous suppression of the NC phase on the nanoscale\, particularly at interphase boundaries [3]. In a complementary approach\, the establishment of three-dimensional IC CDW order is accessible by means of ultrafast electron diffraction [4]. Specifically\, the high-coherence electron source of the Göttingen UTEM [2] enables collimated diffractive probing of nanometer-sized\, spatially homogenous sample regions with high reciprocal-space resolution (Fig. 1c). \n \nFig. 1. a) UTEM schematics. b) Evolution of the CDW spot intensity of the IC (red) and the NC phase (blue). c) Characterisation of in-plane disorder. Transient hexatic order is encoded in the azimuthally broadened diffraction spots (brown arrow). d) CDW rocking curves. We find similar spot broadening also along the out-of-plane direction\, indicative of a dimensional crossover. \nBased on a tomographic reconstruction of the CDW diffraction spot shape during the dynamics\, we identify an initial loss of interlayer correlations (Fig. 1d). Along the in-plane directions\, this dimensional crossover is corroborated by a suppression of translational\, but intact orientational order\, paralleling the phenomenology of a hexatic phase [5]. We conclude that\, in close analogy\, the phase transition observed here unfolds via a network of topological point defects and a transient hexatic state. \nOur results show how optical excitation can induce low-dimensional behaviour in functional materials. In the future\, we expect ultrafast nanobeam electron diffraction to further enhance the investigation of non-equilibrium dynamics in the presence of spatial heterogeneity. \n\nA. Zewail\, Science 328\, 187-193 (2010)\nA. Feist et al.\, Ultramicroscopy 176\, 63-73 (2017)\nTh. Danz\, T. Domröse\, C. Ropers\, Science 371\, 371-374 (2021)\nT. Domröse et al.\, Nat. Mater. (2023)\nD. Nelson\, B. Halperin\, Physical Review B 19\, 2457-2484 (1979)
URL:https://nqw.ijs.si/event/till-domrose-light-induced-hexatic-state-observed-by-ultrafast-nanobeam-diffraction/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T100000
DTEND;TZID=Europe/Ljubljana:20231214T101500
DTSTAMP:20260507T120305
CREATED:20231201T190420Z
LAST-MODIFIED:20231207T151644Z
UID:2616-1702548000-1702548900@nqw.ijs.si
SUMMARY:Anze Mraz: Switching of the nanocryotron-driven ‌charge configuration memristor in real time
DESCRIPTION:A. Mraz\,1\,2 R. Venturini\,1\,3 D. Svetin\,1\,2 I. Vaskivskyi\,1\,2 T. Lotrič\,1 B. Brezec\,1 M. Merljak\,1D. Kazazis\,4 J. Ravnik\,4 S. Gerber\,4 Y. Ekinci\,4 V.V. Kabanov\,1 D. Mihailovic1\,2 \n1Jozef Stefan Institute\, Dept. of Complex Matter\, Jamova 39\, SI-1000 Ljubljana\, Slovenia \n2CENN Nanocenter\, Jamova 39\, SI-1000 Ljubljana\, Slovenia \n3Faculty for Mathematics and Physics\, University of Ljubljana\, Jadranska 19\, SI-1000 Ljubljana\, Slovenia \n4LMN-Paul Scherrer institute\, Villigen\, Switzerland \nTo improve the field of superconducting computer systems\, a low-power\, fast and durable memory device that is compatible with the single-flux-quantum (SFQ) logic is needed [1\,2]. Here we report on recent progress in the development of a so-called parallelotron (pTron) [3] device that comprises a superconducting three-terminal amplifying nanowire cryotron (nTron) [4] and a charge configuration memristor (CCM) [5\,6] based on 1T-TaS2. Besides the current-voltage characteristics and read operation\, we also record switching of the device in real time when the switching pulse is applied to the control terminal. Measured results show great matching to model predictions\, demonstrating the validity of the model and its potential usefulness for future optimization of the device’s parameters. We briefly discuss the effect of noise on the switching capabilities of the pTron device. \n\nHolmes\, D. S. et al. IEEE Trans. Appl. Supercond. 23\, 1701610–1701610 (2013)\nTafuri. F. Fundamentals and Frontiers of the Josephson Effect. vol. 286 (Springer International Publishing\, 2019)\nMraz\, A. et al. doi:10.48550/ARXIV.2203.14586 (2022)\nMcCaughan\, A. et al. Nano Lett. 14\, 5748–5753 (2014)\nStojchevska\, L. et al. Science 344\, 177–180 (2014)\nVaskivskyi\, I. et al. Nat. Commun. 7\, (2016)
URL:https://nqw.ijs.si/event/anze-mraz-switching-of-the-nanocryotron-driven-charge-configuration-memristor-in-real-time/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T101500
DTEND;TZID=Europe/Ljubljana:20231214T104500
DTSTAMP:20260507T120305
CREATED:20231201T195418Z
LAST-MODIFIED:20231207T151644Z
UID:2758-1702548900-1702550700@nqw.ijs.si
SUMMARY:Coffee Break
DESCRIPTION:
URL:https://nqw.ijs.si/event/coffee-break-7/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T104400
DTEND;TZID=Europe/Ljubljana:20231214T120000
DTSTAMP:20260507T120305
CREATED:20231207T151644Z
LAST-MODIFIED:20231207T151659Z
UID:3160-1702550640-1702555200@nqw.ijs.si
SUMMARY:Chair: Federico Cilento
DESCRIPTION:
URL:https://nqw.ijs.si/event/chair-federico-cilento/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T104500
DTEND;TZID=Europe/Ljubljana:20231214T111500
DTSTAMP:20260507T120305
CREATED:20231201T190435Z
LAST-MODIFIED:20231207T151644Z
UID:2618-1702550700-1702552500@nqw.ijs.si
SUMMARY:Tomaz Mertelj: Unconventional photo-induced charge-density-wave dynamics ‌in 2H-NbSe2 compared to the conventional in 1T-VSe2
DESCRIPTION:R. Venturini\,1 A. Sarkar\,1 P. Sutar\,1 D. Vengust\,1 D. Grabnar\,1 Z. Jagličić\,2\,3Y. Vaskivskyi\,1 E. Goreshnik\,4 D. Mihailovic\,1\,5 T. Mertelj1\,5 \n1Department of Complex Matter\, Jozef Stefan Institute\, Jamova 39\, 1000 Ljubljana\, Slovenia \n2Faculty of Civil and Geodetic Engineering\, University of Ljubljana\, Jamova cesta 2\, Ljubljana\, Slovenia \n3Institute of Mathematics\, Physics and Mechanics\, Jadranska 19\, Ljubljana\, Slovenia \n4Dept. of Inorganic Chemistry and Technology\, Jozef Stefan Institute\, Jamova 39\, 1000 Ljubljana\, Slovenia \n5Center of Excellence on Nanoscience and Nanotechnology Nanocenter (CENN Nanocenter)\, Jamova 39\, 1000 Ljubljana\, Slovenia \nWe investigated temperature dependent ultrafast near-infrared transient reflectivity dynamics in coexisting superconducting (SC) and charge density wave (CDW) phases of layered 2H-NbSe2 using NIR and visible excitations. With visible pump-photon excitation (400 nm) we find a slow high-energy quasiparticle relaxation channel which is present in all phases. In the CDW phase\, we observe a distinctive transient response component. The component is marked by the absence of coherent amplitude mode oscillations and a relatively slow\, picosecond rise time\, which is different than in most of the typical CDW materials\, such as 1T-VSe2.  \nIn the SC phase\, another tiny component emerges that is associated with optical suppression of the SC phase. The transient reflectivity relaxation in the CDW phase is dominated by phonon diffusive processes with an estimated low-T heat diffusion constant anisotropy of ~ 30. Strong excitation of the CDW phase reveals a weakly non-thermal CDW order parameter (OP) suppression. Unlike CDW systems with a larger gap\, where the optical OP suppression involves only a small fraction of phonon degrees of freedom\, the OP suppression in 2H-NbSe2 is characterized by the excitation of a large number of phonon degrees of freedom and significantly slower dynamics. \n \nFig. 1. Temperature dependent transient reflectivity in 2H-NbSe2 and 1T-VSe2.
URL:https://nqw.ijs.si/event/tomaz-mertelj-unconventional-photo-induced-charge-density-wave-dynamics-in-2h-nbse2-compared-to-the-conventional-in-1t-vse2/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T111500
DTEND;TZID=Europe/Ljubljana:20231214T113000
DTSTAMP:20260507T120305
CREATED:20231201T190435Z
LAST-MODIFIED:20231207T151644Z
UID:2619-1702552500-1702553400@nqw.ijs.si
SUMMARY:Manuel Tuniz: Manipulation of the charge-density-wave in VTe2 ‌by femtosecond light pulses
DESCRIPTION:M. Tuniz\,1 W. Bronsch\,2 D. Puntel\,1 D. Soranzio\,3 D. Bidoggia\,1M. Peressi\,1 F. Parmigiani\,1\,2 F. Cilento2 \n1Dipartimento di Fisica\, Università degli Studi di Trieste\, Italy \n2Elettra – Sincrotrone Trieste S.C.p.A.\, Italy \n3Institute for Quantum Electronics\, ETH Zürich\, 8093 Zurich\, Switzerland. \nBy combining time and angle-resolved photoemission spectroscopy (tr-ARPES) and broadband time-resolved optical spectroscopy (TR-OS) we investigate the effect of an optical excitation on the electronic and structural properties of the charge-density wave (CDW) system VTe2. Recently\, the modification of the material’s electronic structure induced by CDW formation has been discussed because the strongly orbital-dependent changes may give rise to a topological change in specific bands [1]. \nIn our contribution\, we show by means of TR-OS measurements the possibility to optically excite the amplitude mode (AM) of the CDW phase and therefore couple to the CDW condensate [2]. Moreover\, by studying the partial closing of the CDW gap our tr-ARPES experiments unveil a major role played by the lattice degrees of freedom in the stabilization of the CDW phase in VTe2. \n\nMitsuishi\, N. et al. Nat Commun. 11\, 2466 (2020)\nTuniz\, M. et al. arXiv:2305.03528 (2023)
URL:https://nqw.ijs.si/event/manuel-tuniz-manipulation-of-the-charge-density-wave-in-vte2-by-femtosecond-light-pulses/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T113000
DTEND;TZID=Europe/Ljubljana:20231214T114500
DTSTAMP:20260507T120305
CREATED:20231201T190435Z
LAST-MODIFIED:20231202T211022Z
UID:2620-1702553400-1702554300@nqw.ijs.si
SUMMARY:Iris Ulčakar: Iterative construction of conserved quantities ‌in dissipative nearly integrable systems
DESCRIPTION:I. Ulčakar\,1\,2 Z. Lenarčič1 \n1Jožef Stefan Institute\, SI-1000 Ljubljana\, Slovenia \n2University of Ljubljana\, Faculty for physics and mathematics\, SI-1000 Ljubljana\, Slovenia \nIntegrable systems offer rare examples of solvable many-body problems in the quantum world. Due to the fine-tuned structure\, their realization in nature and experiment is never completely accurate\, therefore effects of integrability are observed only transiently. One way to surpass that is to couple nearly integrable systems to baths and driving: these will stabilize integrable effects up to arbitrary time\, as encoded in the time dependent\, and eventually\, the stationary state of form of a generalized Gibbs ensemble. However\, the description of such driven dissipative nearly integrable models is challenging and no exact analytical methods have been proposed so far. Here we develop an iterative scheme in which integrability breaking perturbations (baths) determine the most necessary conserved quantities to be added into a truncated generalized Gibbs ensemble description. Our scheme significantly reduces the complexity of the problem\, paving the way for thermodynamic results. \n\nI. Ulčakar and Z. Lenarčič\, arXiv:2310.03809 (2023)
URL:https://nqw.ijs.si/event/iris-ulcakar-iterative-construction-of-conserved-quantities-in-dissipative-nearly-integrable-systems/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T114500
DTEND;TZID=Europe/Ljubljana:20231214T120000
DTSTAMP:20260507T120305
CREATED:20231201T190435Z
LAST-MODIFIED:20231202T211022Z
UID:2621-1702554300-1702555200@nqw.ijs.si
SUMMARY:Jože Gašperlin: The interplay of lattice dynamics\, stacking effects and Mott physics ‌in charge-density-wave systems
DESCRIPTION:J. Gašperlin\,1\,2 D. Golež1\,2 \n1Jožef Stefan Institute\, 1000 Ljubljana\, Slovenia \n2Faculty of Mathematics and Physics\, University of Ljubljana\, 1000 Ljubljana\, Slovenia \nThe transition metal dichalcogenide 1T-TaS2 is a layered compound that exhibits a series of increasingly commensurate charge density wave phases with decreasing temperature\, including a low-temperature insulating phase. For a single 1T-TaS2 layer\, with an odd number of electrons per Star-of-David cluster\, the insulating behaviour may be attributed to Mott localisation. However\, the stacking arrangement of multiple layers can lead to doubling of the unit cell\, where the nature of the insulating state is ambiguous [1\, 2]. Furthermore\, the various possible stacking terminations lead to surface states with non-trivial interplay between band-insulating and Mott-insulating behaviour. [3].  \nWe propose a minimal model\, motivated by the Peierls transition\, to investigate the influence of these degrees of freedom. The model describes a (semi-bulk) stack of coupled one-dimensional chains at half-filling. Charge-density-wave order is introduced through Peierls electron-lattice coupling in the transverse direction\, and treated at the mean-field level. We present the equilibrium phase diagram of the model\, demonstrating regions where\, as a result of layer stacking\, the trimerized phase is stabilized instead of the expected dimerized phase. We identify a narrow band crossing the Fermi level and opening of the Mott gap due to on-site electron-electron interactions.  \n\nC. J. Butler et al.\, Nat. Commun. 11\, 2477\, (2020)\nT. Ritschel et al\, Phys. Rev. B 98\, 195134 (2018)\nF. Pettochi et al.\, Phys. Rev. Lett. 129\, 016402\, (2022)
URL:https://nqw.ijs.si/event/joze-gasperlin-the-interplay-of-lattice-dynamics-stacking-effects-and-mott-physics-in-charge-density-wave-systems/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T120000
DTEND;TZID=Europe/Ljubljana:20231214T121500
DTSTAMP:20260507T120305
CREATED:20231201T195422Z
LAST-MODIFIED:20231213T145038Z
UID:2759-1702555200-1702556100@nqw.ijs.si
SUMMARY:Igor Vaskivskyi: Closing NQW 2023
DESCRIPTION:
URL:https://nqw.ijs.si/event/closing-nqw-2023/
CATEGORIES:NQW 2023
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Ljubljana:20231214T121500
DTEND;TZID=Europe/Ljubljana:20231214T133000
DTSTAMP:20260507T120305
CREATED:20231212T162545Z
LAST-MODIFIED:20231212T162709Z
UID:3167-1702556100-1702560600@nqw.ijs.si
SUMMARY:Lunch
DESCRIPTION:
URL:https://nqw.ijs.si/event/lunch-8/
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