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X-WR-CALNAME:Theoretical Quantum Matter
X-ORIGINAL-URL:https://tqmatter.org
X-WR-CALDESC:Events for Theoretical Quantum Matter
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TZID:Europe/Stockholm
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DTSTART:20191027T010000
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DTSTART:20211031T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200212T080000
DTEND;TZID=Europe/Stockholm:20200216T170000
DTSTAMP:20260501T193306
CREATED:20200130T085231Z
LAST-MODIFIED:20200713T184819Z
UID:1656-1581494400-1581872400@tqmatter.org
SUMMARY:HERO Retreat & Meeting '20
DESCRIPTION:Location: TBC\, Switzerland\nDate: 12-16th February\nOrganizers: Alexander Balatsky\, \nSchedule TBA
URL:https://tqmatter.org/event/hero-retreat-meeting-20/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200211T150000
DTEND;TZID=Europe/Stockholm:20200211T163000
DTSTAMP:20260501T193307
CREATED:20200124T173956Z
LAST-MODIFIED:20200713T184819Z
UID:1645-1581433200-1581438600@tqmatter.org
SUMMARY:[Group Meeting] Long Liang
DESCRIPTION:Talk by Long Liang (Nordita). Details TBH
URL:https://tqmatter.org/event/group-meeting-long-liang/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200210T160000
DTEND;TZID=Europe/Stockholm:20200210T163000
DTSTAMP:20260501T193307
CREATED:20200209T123653Z
LAST-MODIFIED:20200713T184819Z
UID:1661-1581350400-1581352200@tqmatter.org
SUMMARY:Long Liang -  Weyl semimetals in torsional spacetime
DESCRIPTION:Title: Weyl semimetals in torsional spacetime\n\n\n\n\nAbstract: Weyl semimetals necessarily break the time-reversal or/and inversion symmetry. In the presence of spatially varying time-reversal or inversion symmetry breaking fields\, we show that the Weyl fermions live in emergent torsional spacetime [1\,2]. This allows us to fabricate interface between type I and type II Weyl semimetals [1]\, which is analogous to the black hole horizon. Torsion also contributes to the chiral anomaly [3]\, and this leads to a thermal magnetotorsional effect\, which means that magnetization gradients perpendicular to the Weyl node separation give rise to temperature gradients depending only on the local positions of the Weyl nodes [2].  This effect could be observed in magnetic Weyl semimetal EuCd2As2 [4].\n\n\n\n\n\nReferences:\n[1] Long Liang and Teemu Ojanen\, Phys. Rev. Research 1\, 032006(R)(2019).\n[2] Long Liang and Teemu Ojanen\, arXiv: 1912.07732.\n[3] J. Nissinen and G.E. Volovik\, arXiv: 1909.08936; Ze-Min Huang\, Bo Han\, and Michael Stone\, arXiv: 1911.00174.\n[4] Lin-Lin Wang et al.\, Phys. Rev. B 99\, 245147 (2019); J.-Z. Ma et al.\,  Sci. Adv. 5 \, 4718 (2019); J.-R. Soh et al.\, Phys. Rev. B 100\, 201102(R) (2019).\n\n\n 
URL:https://tqmatter.org/event/long-liang-weyl-semimetals-in-torsional-spacetime/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200210T130000
DTEND;TZID=Europe/Stockholm:20200210T170000
DTSTAMP:20260501T193307
CREATED:20200209T123809Z
LAST-MODIFIED:20200713T184819Z
UID:1663-1581339600-1581354000@tqmatter.org
SUMMARY:Andrea Amoretti - A hydrodynamical description for transport in the strange metal phase of cuprates
DESCRIPTION:  \n\nTitle: A hydrodynamical description for transport in the strange metal phase of cuprates\n Speaker: Andrea Amoretti (Genova)\n\nThe talk is on Monday 10 February 2020\, 13:15\, room 132:028 (Nordita East). \n\nAbstract: High temperature superconductors are strongly coupled systems which present a complicated phase diagram with many coexisting phases. This makes it difficult to understand the mechanism which generates their singular transport properties. Hydrodynamics\, which mostly relies on the symmetries of the system without referring to any specific microscopic mechanism\, constitutes a promising framework to analyze these materials. In this talk I will show that in the strange metal phase of the cuprates\, a whole set of transport coefficients are described by a universal hydrodynamic framework. We corroborate our theoretical prediction by measuring the DC transport properties of Bi-2201 close to optimal doping\, proving the validity of our approach. Our argument can be used as a consistency check to understand the universality class governing the behavior of high temperature cuprate superconductors\n\n 
URL:https://tqmatter.org/event/andrea-amoretti-a-hydrodynamical-description-for-transport-in-the-strange-metal-phase-of-cuprates/
LOCATION:NORDITA\, 11 Roslagstullsbacken\, Stockholm\, Sweden
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200204T110000
DTEND;TZID=Europe/Stockholm:20200204T120000
DTSTAMP:20260501T193307
CREATED:20200204T093650Z
LAST-MODIFIED:20200713T184819Z
UID:1658-1580814000-1580817600@tqmatter.org
SUMMARY:Danny Thonig - Ultrafast magnetism from ab-initio atomistic magnetisation dynamics
DESCRIPTION:Speaker: Danny Thonig (Örebro Universitet) \nTitle: Ultrafast magnetism from ab-initio atomistic magnetisation dynamics \nTime: Fika 10:30-11:00 \, Seminar 11:00-12:00\, \nPlace: Nordita South\, room 112:028 . \nAbstract:\nWriting and retrieving information in a magnetic material at high speed and with lower energy consumption has become an intense research field in solid state physics\, since there is growing benefits for our society and within technical applications. For instance\, by using all-optical control of magnetism\, local magnetic moments can achieve remarkably fast switching times. The pioneering work by Beaurepaire et al. [1] demonstrated dynamics on a pico second time-scale. The experiment of Ref. [1] used a high-intensity laser pulse that pumped the sample\, and after a time-delay\, a second laser pulse was used to probe its magnetic state\, via the magneto-optical effect. All hitherto proposed mechanisms of ultrafast magnetism (e.g. Refs. [2] and [3]) have been criticized\, for not being consistent with observations and/or for not being physically relevant (reviewed e.g. in Ref.[4]). The most pressing\, open questions connected to these experiments concerns the transfer of angular momentum.\nTo describe ultrafast magnetism from first-principles\, we used atomistic magnetisation dynamics combined with density functional theory. The latter serves to calculate fundamental magnetic properties\, magnetic interaction\, and energy dissipation contributions.\nWe applied this machinery naturally to a wide range of materials\, as recently also to Heusler and inverse Heusler materials. We studied demagnetisation and remagnetisation behaviour for different structural phases of Heusler’s and compared our results to experimental measurements with qualitative good agreement. \n[1] E. Beaurepaire et al.\, Phys. Rev. Lett. 76\, 4250 (1996).\n[2] B. Koopmans et al.\, J. Magn. and Magn. Mater. 286\, 271 (2005).\n[3] M. Battiato et al.\, Phys. Rev. Lett. 105\, 027203 (2010).\n[4] O. Eriksson\, A.Bergman\, L.Bergqvist and J.Hellsvik\, Atomistic Spin-Dynamics\, fundamentals and applications (Oxford university press\, 2017).
URL:https://tqmatter.org/event/danny-thonig-ultrafast-magnetism-from-ab-initio-atomistic-magnetisation-dynamics/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200204T103000
DTEND;TZID=Europe/Stockholm:20200204T120000
DTSTAMP:20260501T193307
CREATED:20200130T085020Z
LAST-MODIFIED:20200713T184820Z
UID:1654-1580812200-1580817600@tqmatter.org
SUMMARY:[CMT] Danny Thonig ( Örebro University)
DESCRIPTION:Abstract TBA
URL:https://tqmatter.org/event/cmt-danny-thonig-orebro-university/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20200114T150000
DTEND;TZID=Europe/Stockholm:20200114T163000
DTSTAMP:20260501T193307
CREATED:20200113T094208Z
LAST-MODIFIED:20200713T184820Z
UID:1618-1579014000-1579019400@tqmatter.org
SUMMARY:[Talk] Hui-Ke Jin - Efficient tensor network representation for Gutzwiller projected states of paired fermions
DESCRIPTION:Title: Efficient tensor network representation for Gutzwiller projected states of paired fermions\n\nAbstract: Recent work by Y.H. Wu {\em et al}\, [arXiv:1910.11011] proposed a numerical method\, so called MPO-MPS method\, by which several types of quantum many-body wave functions\, in particular\, the projected Fermi sea state\, can be efficiently represented as a tensor network. In this paper\, we generalize the MPO-MPS method to study Gutzwiller projected paired states of fermions\, where the maximally localized Wannier orbitals for Bogoliubov quasiholes/quasiparticles have been adapted to improve the computational performance. The study of $SO(3)$ spin-1 chains reveals that this new method has better performance than variational Monte Carlo for gapped states and similar performance for gapless states. Moreover\, we demonstrate that dynamic correlation functions can be easily evaluated by this method cooperating with other MPS-based accurate approaches\, such as Chebyshev MPS method.
URL:https://tqmatter.org/event/talk-hui-ke-jin-efficient-tensor-network-representation-for-gutzwiller-projected-states-of-paired-fermions/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191210T140000
DTEND;TZID=Europe/Stockholm:20191210T150000
DTSTAMP:20260501T193307
CREATED:20191209T115459Z
LAST-MODIFIED:20200713T184820Z
UID:1608-1575986400-1575990000@tqmatter.org
SUMMARY:[Talk] Bastiaan J. Braams - Machine learning of equivariant functions inspired by atomistic modelling and three-dimensional image processing.
DESCRIPTION:Title: Machine learning of equivariant functions inspired by atomistic modelling and three-dimensional image processing.\n\nSpeaker: Bastiaan J. Braams\, Centrum Wiskunde & Informatica (CWI)\, Amsterdam\, The Netherlands.\n\nAbstract: \nOver the past several years big data methods\, including but not limited to use of deep convolutional neural networks\, have been very successful in computer science applications and there is increasing effort to apply big data or machine learning methods to problems in physical science and engineering. Conversely we are seeing that problems from physical science are influencing machine learning research done in computer science environments. A very important application of big data methods in physical science where we see this mutual influence is the construction of effective interatomic potentials and force fields for atomistic modelling of molecular and condensed phase systems (e.g. [1]). This application shares features with certain applications in three-dimensional image processing in having data associated with point clouds and in seeking to represent functions that are invariant or covariant with respect to a permutation group (applied to the labelling of points in the cloud) and with respect to spatial groups of translations\, rotations and inversion. Some by now almost classical big data approaches to the atomistic problem include use of Gaussian process approximation (kernel ridge regression) [2] and use of spherical wavelet expansions [3]. In addition deep neural networks are being applied (e.g. [4]\, [5]) and here we see the closest link to machine learning research with key words such as Point Cloud Convolutional Networks\, Deep Sets\, Spherical CNNs\, Tensor Field Networks and Gauge Equivariant Neural Networks [6]. The presentation will provide a survey of these machine learning developments in the context of the application in physical science.\n\nReferences:\n[1] Ceriotti\, Michele. “Atomistic machine learning between predictions and understanding.” arXiv preprint arXiv:1902.05158 (2019).\n[2] Bartók\, Albert P.\, and Gábor Csányi. “Gaussian approximation potentials: A brief tutorial introduction.” International Journal of Quantum Chemistry 115\, no. 16 (2015): 1051-1057.\n[3] Eickenberg\, Michael\, Georgios Exarchakis\, Matthew Hirn\, Stéphane Mallat\, and Louis Thiry. “Solid harmonic wavelet scattering for predictions of molecule properties.” The Journal of chemical physics 148\, no. 24 (2018): 241732.\n[4] Schütt\, Kristof T.\, Huziel E. Sauceda\, P-J. Kindermans\, Alexandre Tkatchenko\, and K-R. Müller. “SchNet–A deep learning architecture for molecules and materials.” The Journal of Chemical Physics 148\, no. 24 (2018): 241722.\n[5] Zhang\, Linfeng\, Jiequn Han\, Han Wang\, Wissam Saidi\, Roberto Car\, and Weinan E. “End-to-end symmetry preserving inter-atomic potential energy model for finite and extended systems.” In Advances in Neural Information Processing Systems\, pp. 4441-4451. 2018.\n[6] Extensive further references to be provided in the presentation.
URL:https://tqmatter.org/event/talk-bastiaan-j-braams-machine-learning-of-equivariant-functions-inspired-by-atomistic-modelling-and-three-dimensional-image-processing/
LOCATION:NORDITA // West (Meeting Room 122:026)
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191206T103000
DTEND;TZID=Europe/Stockholm:20191206T120000
DTSTAMP:20260501T193307
CREATED:20191206T144748Z
LAST-MODIFIED:20200713T184820Z
UID:1601-1575628200-1575633600@tqmatter.org
SUMMARY:HERO Meeting
DESCRIPTION:
URL:https://tqmatter.org/event/hero-meeting/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191122T110000
DTEND;TZID=Europe/Stockholm:20191122T170000
DTSTAMP:20260501T193307
CREATED:20191120T154913Z
LAST-MODIFIED:20200713T184820Z
UID:1598-1574420400-1574442000@tqmatter.org
SUMMARY:Kazuki Ikeda (Osaka) - Mathematics and Physics of Hofstadter Butterfly\, and Quantum Computation 
DESCRIPTION:Speaker: Kazuki Ikeda from Osaka university.\nTitle: Mathematics and Physics of Hofstadter Butterfly\,\nand Quantum Computation\n\nAbstract:\nQuantum Hall effect (QHE) is one of the most important phenomena in condensed matter physics\, high energy physics\, and mathematical physics. Especially QHE is the crucial for the recent advances in symmetry protected topological phase and topological quantum computation. In my talk\, I’ll explain the mathematics and physics of QHE by the following plan.\n\nIn part 1\, I explain mathematical foundation of quantum Hall effect and Hofstadter butterfly from a viewpoint of the Langlands program\, which is the “grand unification theory” of mathematics. In part 2\, I address the Hofstadter problem on a lattice with defects. I show the energy spectra associated with the localised current around the defect appear in the energy gaps of fractal butterfly. In part 3\, I describe application of adiabatic quantum computation to the material search.
URL:https://tqmatter.org/event/kazuki-ikeda-osaka-mathematics-and-physics-of-hofstadter-butterfly-and-quantum-computation/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Talks
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191120T110000
DTEND;TZID=Europe/Stockholm:20191120T120000
DTSTAMP:20260501T193307
CREATED:20191119T125650Z
LAST-MODIFIED:20200713T184820Z
UID:1596-1574247600-1574251200@tqmatter.org
SUMMARY:Open Acess Publishing - Peter Mitchell (IntechOpen)
DESCRIPTION:Open Access books presentation / Q&A Session\n\nPeter Mitchell (IntechOpen\, London)\n20 November\n \nYou are invited to join a short session with Peter Mitchell from IntechOpen\, a start-up publisher specialising in Open Access books and progressive funding models.\nThe session will cover:\n \n\nDisseminating your work with impact: the benefits of non-journal Open Access publishing\nFunding Open Access\, including a new “no-author-fee fund” for physicists\, engineers\, and computer scientists\nQ&A: ask anything about Open Access text and reference\, ideas for new works\, how to submit a proposal\, etc. \n\n\n 
URL:https://tqmatter.org/event/open-acess-publishing-peter-mitchell-intechopen/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191114T150000
DTEND;TZID=Europe/Stockholm:20191114T160000
DTSTAMP:20260501T193307
CREATED:20191114T102759Z
LAST-MODIFIED:20200713T184820Z
UID:1594-1573743600-1573747200@tqmatter.org
SUMMARY:[Colloquium] A. Balatsky - Dynamic Quantum Matter
DESCRIPTION:Speaker: Alexander Balatsky from NORDITA.\n \nTitle:  Dynamic Quantum Matter\nTime and place: Thursday November 14 at 15.15 (coffee and tea from 15.00) in the Oskar Klein auditorium FR4.
URL:https://tqmatter.org/event/colloquium-a-balatsky-dynamic-quantum-matter/
CATEGORIES:Talks
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191112T150000
DTEND;TZID=Europe/Stockholm:20191112T160000
DTSTAMP:20260501T193307
CREATED:20191112T125505Z
LAST-MODIFIED:20191112T125505Z
UID:1588-1573570800-1573574400@tqmatter.org
SUMMARY:Group Meeting
DESCRIPTION:Schedule: \nPresentation by Razmik.
URL:https://tqmatter.org/event/group-meeting-7/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Group Meetings
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191107T164500
DTEND;TZID=Europe/Stockholm:20191107T171500
DTSTAMP:20260501T193307
CREATED:20191106T115259Z
LAST-MODIFIED:20191106T115259Z
UID:1582-1573145100-1573146900@tqmatter.org
SUMMARY:Di Peng - Antiferromagnetic order and possible quantum spin liquid in sodium doped 2\,2′-bipyridine  
DESCRIPTION:Antiferromagnetic order and possible quantum spin liquid in sodium doped 2\,2′-bipyridine\n \nDi Peng\nCenter for High Pressure Science and Technology Advanced Research\, Shanghai 201203\, China\n \nOrganic molecular solids with correlated electronics based on π-electron networks provide fertile ground for the search for peculiar materials\, including antiferromagnetic and quantum magnetism.  We report a development method for doping alkali metals into organic materials and forming a homogeneous phase together with the experimental discoveries of two antiferromagnetic phase in sodium doped 2\,2′-bipyridine at different molar ratios. An antiferromagnetic phase of 160 K is found in sodium-doped 2\,2′-bipyridine with a molar ratio of less than 1:1. Another antiferromagnetic phase with Neel temperature of 25 K is observed in samples with molar ratios of 1:1 and 1:2. Applying magnetic field can slowly suppress the 160 K antiferromagnetic phase\, while the 25 K antiferromagnetic phase is insensitive to the applied field rather than showing an increase of magnetization below 6 K. This behavior is consistent with the characteristics of quantum spin liquid\, in which strong quantum fluctuations lead to the disorder at low temperatures. We will discuss more about the experimental details about whether a strong spin frustrated antiferromagnetic phase is formed in sodium-doped 2\,2′-bipyridine and whether it enters a quantum spin liquid state at low temperatures.\n\n 
URL:https://tqmatter.org/event/di-peng-antiferromagnetic-order-and-possible-quantum-spin-liquid-in-sodium-doped-22%e2%80%b2-bipyridine/
CATEGORIES:Talks
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191107T161500
DTEND;TZID=Europe/Stockholm:20191107T164500
DTSTAMP:20260501T193307
CREATED:20191106T115210Z
LAST-MODIFIED:20191106T115210Z
UID:1580-1573143300-1573145100@tqmatter.org
SUMMARY:Ren-Shu Wang - Exploring superconductivity in organobismuth molecules
DESCRIPTION:Exploring superconductivity in organobismuth molecules\n \nRen-Shu Wang\nCenter for High Pressure Science and Technology Advanced Research\, Shanghai 201203\, China\n \nRecently\, novel quantum phenomena such as topological insulators and superconductors were suggested in organometallic materials. Three different types of organobismuth molecules\, including triphenylbismuth (TPB)\, tri-p-tolylbismthine (p-TTB)\, and tri-o-tolylbismthine (o-TTB)\, were investigated to explore organic superconductivity by alkali metal doping. The target organic molecules have similar structures\, expect for the type and the position of the functional group. The dc and ac magnetic susceptibility\, and electrical resistivity measurements reveal that all these doped molecules exhibit superconductivity\, and their Tc’s vary from 3.5 (and/or 7.2) to 3.6 (and/or 5.3) and 3.6 K for K-doped TPB\, p-TTB\, and o-TTB\, respectively. The shield fractions (SFs) of the main superconducting phases at 1.8 K are 3.74%\, 18%\, and 17% for K-doped TPB\, p-TTB\, and o-TTB\, respectively. In comparison with TPB\, adding the -CH3 groups in p-TTB and o-TTB do not make much difference for Tc of main phase rather than bringing about the increase of the SF\, indicating that the simple addition of functional groups is an effective way to tune (super)conductivity in such materials. The main superconducting phases and their composition in these molecules are determined by combined studies of X-ray diffraction and theoretical calculations as well as Raman spectroscopy measurements. These findings enrich the applications of organometallic compounds in superconductivity and add a new electron-acceptor family of organic superconductors. \n\n  \n\n\n 
URL:https://tqmatter.org/event/ren-shu-wang-exploring-superconductivity-in-organobismuth-molecules/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Talks
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191107T150000
DTEND;TZID=Europe/Stockholm:20191107T160000
DTSTAMP:20260501T193307
CREATED:20191106T115721Z
LAST-MODIFIED:20191106T115721Z
UID:1586-1573138800-1573142400@tqmatter.org
SUMMARY:[Colloqium] David Cassidy - Recent experimental progress in positronium-laser physics
DESCRIPTION:Speaker: David Cassidy from the University College London. \nTitle: Recent experimental progress in positronium-laser physics \nTime and place: Thursday November 7 at 15.15 (coffee and tea from 15.00) in the Oskar Klein auditorium FR4. \nAbstract:\nThe field of experimental positronium physics has advanced significantly in recent years\, in many cases by employing new techniques for trapping and manipulating positrons using Surko-type buffer gas traps [1]. These devices capture and store positrons\, allowing for the production of high quality DC beams\, or high intensity pulsed beams. The latter approach can be used to create an instantaneous cloud of Ps atoms that can be probed with standard ns pulsed lasers. This allows for the optical production of excited Ps states\, ranging from 2P levels\, which decay back to the ground state in 3.2 ns\, to metastable 2S states\, that cannot decay radiatively\, but will self-annihilate (in 1.1 microseconds)\, to long-lived Rydberg states\, that do not annihilate at all and\, for easily produced states\, may have radiative lifetimes of hundreds of microseconds [2]. The ability to generate Ps atoms in excited states facilitates numerous experimental programs [3]\, including precision optical and microwave spectroscopy and the application of Stark deceleration methods to guide\, decelerate and focus Rydberg Ps beams. In this talk I will discuss recent examples of such experiments and what may be possible in the near future. \nReferences\n[1] Plasma and trap-based techniques for science with positrons\, J. R. Danielson\, D. H. E. Dubin\, R. G. Greaves\, and C. M. Surko\, Rev. Mod. Phys. 87\, 247 (2015).\n[2] Measurement of Rydberg positronium fluorescence lifetimes\, A. Deller\, A. M. Alonso\, B. S. Cooper\, S. D. Hogan\, and D. B. Cassidy\, Phys. Rev. A 93\, 062513 (2016).\n[3] Experimental progress in positronium laser physics\, D. B. Cassidy\, Eur. Phys. J. D 72\, 53 (2018).
URL:https://tqmatter.org/event/colloqium-david-cassidy-recent-experimental-progress-in-positronium-laser-physics/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191107T140000
DTEND;TZID=Europe/Stockholm:20191107T150000
DTSTAMP:20260501T193307
CREATED:20191106T115507Z
LAST-MODIFIED:20191106T115507Z
UID:1584-1573135200-1573138800@tqmatter.org
SUMMARY:Whiteboard discussion - Dirac Materials group & Xiao-Jia
DESCRIPTION:
URL:https://tqmatter.org/event/whiteboard-discussion-dirac-materials-group-xiao-jia/
CATEGORIES:Meeting
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191106T103000
DTEND;TZID=Europe/Stockholm:20191106T120000
DTSTAMP:20260501T193307
CREATED:20191104T123221Z
LAST-MODIFIED:20191104T123221Z
UID:1578-1573036200-1573041600@tqmatter.org
SUMMARY:[CMT] Xiao-Jia Chen - Discovery of Superconductivity in Phenyl Molecules
DESCRIPTION:Speaker: Xiao-Jia Chen (Center for High-Pressure Science & Technology Advanced Research)\n \nTitle: Discovery of superconductivity in phenyl molecules\n \nTime: Wednesday 6th of November\, Fika 10:30-11:00 \, Seminar 11:00-12:00\, \n \nPlace: Nordita South\, room 112:028 .\n\nAbstract:\nOrganic compounds are always promising candidates of superconductors with high transition temperatures Tc’s. In this talk\, we will first talk about our recent discovery of superconductivity with Tc’s as high as 123 K in polyparaphenylene oligomers. Then we will show the experimental realization of superconductivity in other phenyl molecules such as organometallic compounds or compounds only containing C\, H\, and N. The evidence of the appearance of superconductivity is provided by the observations of the measurements of the dc and ac magnetic susceptibility and resistivity measurements together with the opening of superconducting gap detected from Raman spectroscopy. The obtained superconducting parameters classify these phenyl molecules as type-II superconductors. The benzene ring is identified to be the essential superconducting unit in such phenyl compounds. The superconducting phases and their composition are determined by the combined studies of the X-ray diffraction and theoretical calculations as well as the Raman spectroscopy measurements. The easy processability\, light weight\, durability of plastics\, and environmental friendliness of these new phenyl superconductors have great potential for the fine-tuning of electrical properties. This discovery opens a window for exploring superconductivity in phenyl molecules.\n 
URL:https://tqmatter.org/event/cmt-xiao-jia-chen-discovery-of-superconductivity-in-phenyl-molecules/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191105T150000
DTEND;TZID=Europe/Stockholm:20191105T160000
DTSTAMP:20260501T193307
CREATED:20191104T123050Z
LAST-MODIFIED:20191104T123050Z
UID:1576-1572966000-1572969600@tqmatter.org
SUMMARY:Group Meeting
DESCRIPTION:
URL:https://tqmatter.org/event/group-meeting-6/
CATEGORIES:Group Meetings
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191105T103000
DTEND;TZID=Europe/Stockholm:20191105T120000
DTSTAMP:20260501T193307
CREATED:20191104T122927Z
LAST-MODIFIED:20191104T122927Z
UID:1574-1572949800-1572955200@tqmatter.org
SUMMARY:[CMT] Sumanta Bandyopadhyay - Entangled Pauli Principles: the DNA of Quantum Hall Fluids
DESCRIPTION:Speaker: Sumanta Bandyopadhyay (NORDITA)\n \nTitle: Entangled Pauli Principles: the DNA of Quantum Hall Fluids\n \nTime: Tuesday 5th of November\, Fika 10:30-11:00 \, Seminar 11:00-12:00\, \n \nPlace: Nordita South\, room 112:028 .\n\nAbstract:\nA formalism is developed for the rigorous study of solvable fractional quantum Hall parent Hamiltonians with Landau level mixing. The idea of organization through “generalized Pauli principles” is expanded to allow for root level entanglement\, giving rise to “entangled Pauli principles”. Through the latter\, aspects of the effective field theory description become ingrained in exact microscopic solutions for a great wealth of phases for which no similar single Landau level description is known. We discuss in detail braiding statistic\, edge theory\, emergent ground state symmetry and rigorous zero mode counting from a microscopic Hamiltonian in a strongly correlated system. We will further discuss the several other application of this methodology in finding parent Hamiltonian for composite fermion.\n \n 
URL:https://tqmatter.org/event/cmt-sumanta-bandyopadhyay-entangled-pauli-principles-the-dna-of-quantum-hall-fluids/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191029T103000
DTEND;TZID=Europe/Stockholm:20191029T120000
DTSTAMP:20260501T193307
CREATED:20191028T170614Z
LAST-MODIFIED:20191028T170614Z
UID:1556-1572345000-1572350400@tqmatter.org
SUMMARY:[CMT] Ilaria Maccari - Vortex physics in 2D disordered superconductors
DESCRIPTION:Speaker: Ilaria Maccari (KTH)\n \nTitle: Vortex physics in 2D disordered superconductors\n \nTime: Tuesday 29th of October\, Fika 10:30-11:00 \, Seminar 11:00-12:00\, \n \nPlace: Nordita South\, room 112:028 .\n\nAbstract:\nThe  study of quasi-two-dimensional (2D) superconductors can hardly avoid to take into account the presence of vortices. Many real systems\, of both conventional and unconventional superconductors\,  undergoes the superconductor-insulator transition via the Brezinskii-Kosterlitz-Thouless (BKT) transition\, at which the phase coherence of the condensate is destroyed by means of free-vortices proliferation.\nWhen a finite flux of the magnetic field is applied to the films\, the role of vortices becomes even more crucial for the understanding of the superconducting (SC) transition. Indeed\, in this case\, the transition is no longer driven by the vortex-antivortex unbinding\, but rather by the melting of the 2D Abrikosov lattice of vortices. Such melting\, as predicted by the BKT  theory\, afterward refined  by  Halperin\, Nelson and Young (BKTHNY)\, can occur in two steps via an intermediate state called hexatic phase. In real systems\, the observation of the two-step BKTHNY melting could be hindered by the presence of additional ingredients\, such as random pinning\, and also competing phases. In [1]\, we have shown that the 2-dimensional vortex lattice in the a-MoGe thin films follows the BKTHNY sequence of melting as the magnetic field is increased. Identifying the signatures of various transitions on the bulk transport properties of the superconductor\, we construct a vortex phase diagram for a  2D  superconductor.  From a theoretical standpoint\,  the classical XY model with a transverse magnetic field is a very promising candidate to capture the physics experimentally observed and to explore stronger disorder regimes. It constitutes hence a perfect playground for the investigation of the long-standing issue of the emergent glassy-state of the vortex lattice in the presence of disorder.\n \n[1] I. Roy\, S. Dutta\, A. N. Roy Choudhury\, S. Basistha\, I. Maccari\, S. Mandal\, J. Jesudasan\, V.Bagwe\,  C.  Castellani\,  L.  Benfatto\,  P.  Raychaudhuri\,  Phys.  Rev.  Lett.  122  (4)\,  047001 (2019)\n 
URL:https://tqmatter.org/event/cmt-ilaria-maccari-vortex-physics-in-2d-disordered-superconductors/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191029T100000
DTEND;TZID=Europe/Stockholm:20191029T110000
DTSTAMP:20260501T193307
CREATED:20191028T170722Z
LAST-MODIFIED:20191028T170722Z
UID:1558-1572343200-1572346800@tqmatter.org
SUMMARY:Group Meeting
DESCRIPTION:
URL:https://tqmatter.org/event/group-meeting-5/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Group Meetings
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191025T100000
DTEND;TZID=Europe/Stockholm:20191025T170000
DTSTAMP:20260501T193307
CREATED:20191023T093713Z
LAST-MODIFIED:20191023T093713Z
UID:1551-1571997600-1572022800@tqmatter.org
SUMMARY:Nordita-KTH Applied Physics Annual Meeting 2019
DESCRIPTION:Webpage of event can be found here \nThis meeting is intended as a platform of discussion to set up collaborations on KAW (The Knut and Alice Wallenberg Foundation) and future projects. \nSchedule\nThe event will comprise of introductory talks on the theory and experimental side\, intended to last fifteen minutes and open to the floor for discussion for another fifteen minutes\, followed by lunch and discussion about overlap and potential collaborations. \nOn the theory side\nThe Dirac Materials group will ensure the main core skills of our expertise are showcased to the experimental participants or other theoretically-minded participants. \n\nHabib Rostami / Pavlo Sukhachov – Optics and strain effects in TMDs.\nDavid Carvalho – Light-Matter Interactions in Dirac Materials\nBart Olsthoorn – Machine Learning in Material Informatics and Spectroscopy\n\n\n12.30 – Lunch\n\nOn the experimental side\nTBC \n\nCollaboration and overlap discussions. (flexible timing)
URL:https://tqmatter.org/event/nordita-kth-applied-physics-annual-meeting-2019/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Meeting
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191015T150000
DTEND;TZID=Europe/Stockholm:20191015T160000
DTSTAMP:20260501T193307
CREATED:20191015T041816Z
LAST-MODIFIED:20191015T041816Z
UID:1497-1571151600-1571155200@tqmatter.org
SUMMARY:[Group Meeting]
DESCRIPTION:
URL:https://tqmatter.org/event/group-meeting-4/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Group Meetings
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191008T161500
DTEND;TZID=Europe/Stockholm:20191008T170000
DTSTAMP:20260501T193307
CREATED:20190925T180612Z
LAST-MODIFIED:20190925T180612Z
UID:1754-1570551300-1570554000@tqmatter.org
SUMMARY:[Group Meeting] Adrien Bouhon - Weyl Nodes with Non-Abelian Charges
DESCRIPTION:Abstract:\nWeyl points trapped within a C_2T-symmetric plane (C2 = 180 degrees rotation\, and T = time reversal) possess non-Abelian topological charges on top of their chirality. E.g. three-level systems realize the quaternion group. This picture requires to go beyond the modeling of a band structure as a Grassmannian (where a single spectral gap is specified). The non-Abelian nature of Weyl points implies new types of obstruction\, where\, for instance\, two Weyl points with opposite chiralities may not annihilate. Also\, the non-Abelian charges can be converted through the braiding of Weyl points in momentum space. \n \nI will review three different yet equivalent ways of computing the non-Abelian charges: (i) as a non-cyclic phase defined from the parallel transport of the Hamiltonian along a base loop\, (ii) as the Euler class of a two-band subspace over a patch bounded by the base loop\, and (iii) as the winding number of the Pfaffian of the Wilsonnian Hamiltonian – of the two-band subspace – as the base loop flows over the patch.  \n 
URL:https://tqmatter.org/event/group-meeting-adrien-bouhon-weyl-nodes-with-non-abelian-charges/
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191008T150000
DTEND;TZID=Europe/Stockholm:20191008T160000
DTSTAMP:20260501T193307
CREATED:20191007T120227Z
LAST-MODIFIED:20191007T120227Z
UID:1402-1570546800-1570550400@tqmatter.org
SUMMARY:Nobel Prize Announcement - Colloquium
DESCRIPTION:Details: TBA \nhttps://www.kva.se/en/pressrum
URL:https://tqmatter.org/event/nobel-prize-announcement-colloquium/
LOCATION:Oskar Klein Auditorium\, Albanova Campus
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191008T103000
DTEND;TZID=Europe/Stockholm:20191008T120000
DTSTAMP:20260501T193307
CREATED:20191007T115850Z
LAST-MODIFIED:20191007T115850Z
UID:1399-1570530600-1570536000@tqmatter.org
SUMMARY:[CMT Seminar] Joe Bailey - Spin wave dynamics in ultrathin yttriumiron garnet measured with x-ray microscopy
DESCRIPTION:Title: Spin wave dynamics in ultrathin yttriumiron garnet measured with x-ray microscopy \nSpeaker: Joe Bailey\, from the PSI (Switzerland) \nTime: 10:30-11am Fika / 11-12am Talk \nAbstract: Magnonics\, the study and development of devices utilising collective spin excitations\, is a rapidly growing field\, covering both fundamental topics (antiferromagnetism[1]\, quasiparticle condensates[2]) and technological applications (MRAM[3]\, spintronics[4]). Yttrium iron garnet (YIG) is a ferrimagnetic insulator with the lowest known magnon damping factor of any material [5]. This low damping leads to a prevalence of nonlinear effects and notably the room temperature Bose-Einstein condensation (BEC) of magnons first reported by Demokritov et al in 2006[6]\, and subject of a number of investigations since[7]-[10]. Ultrathin structures will be required for applications butremainlargelyunexplored. Here I report on the design\, fabrication and characterization of microwave devicesbased on such ultrathin structures(YIG thickness~100nm).The spin wavedynamics weremeasured using both Brillouin Light Scattering (BLS) and time resolved scanning transmission x-ray microscopy(TR-STXM)\, locked in phase with microwave stimulation of the devices.Anumber of milestonesare reached for our novel devices.First\, we have explicitly measuredthe spin wave dispersion in YIG[11]\, and demonstratedthe existence of the finite momentum minimum required for magnon BEC. Second\, the BLSdata demonstratethat the condensate exists in our samples. These results are a key development towards addingcondensate phenomena to the thin film magnonics toolbox.
URL:https://tqmatter.org/event/cmt-seminar-joe-bailey-spin-wave-dynamics-in-ultrathin-yttriumiron-garnet-measured-with-x-ray-microscopy/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20191007
DTEND;VALUE=DATE:20191008
DTSTAMP:20260501T193307
CREATED:20190903T081848Z
LAST-MODIFIED:20190903T081848Z
UID:1243-1570406400-1570492799@tqmatter.org
SUMMARY:[Seminar]  Vladimir Pudalov
DESCRIPTION:Condensed Matter Seminar Series \nSpeaker: Vladimir Pudalov\, Lebedev Physical Institute \nTitle:“Thermodynamics of the correlated 2D electron system: Entropy per electron and spin magnetization per electron” \n\nAbstract: In contrast to ubiquitous transport and optical measurements\, interpretation of thermodynamic data is straightforward and is often model independent. However\, due to the additive character of thermodynamic properties\, their measurements for 2D electron systems is rather challenging.  I shall report recent advancement in thermodynamic measurements  of the correlated 2D electron system. Particularly\, I focus on the derivatives of the chemical potential with respect to magnetic field and temperature. The former enables to determine spin magnetization per electron and the latter – entropy per electron.\nI shall briefly describe recent results obtained with these technique and their impact on the current understanding of the still debatable problem of the ground state(s) of strongly correlated two-dimensional electron systems. \n 
URL:https://tqmatter.org/event/seminar-vladimir-pudalov/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191002T103000
DTEND;TZID=Europe/Stockholm:20191002T120000
DTSTAMP:20260501T193307
CREATED:20190930T150627Z
LAST-MODIFIED:20190930T150627Z
UID:1375-1570012200-1570017600@tqmatter.org
SUMMARY:[CMT Seminar] Adrian Kantian/ Gunnar Bollmark - 1D electrons coupled to reservoirs: towards new systems of correlated quantum matter and novel devices
DESCRIPTION:Speaker: Adrian Kantian and Gunnar Bollmark (Uppsala University)\n \nTitle: 1-D electrons coupled to reservoirs: towards new systems of correlated quantum matter and novel devices.\n \nTime:  Wednesday\, 2nd of October\, Fika 10:30-11:00 \, Seminar 11:00-12:00\, \n \nPlace: Nordita South\, room 112:028 .\n\nAbstract:\nCorrelated electrons are at the forefront of condensed matter theory. Interacting quasi-1D electrons have seen vast progress in analytical and numerical theory\, and thus in fundamental understanding and quantitative prediction. Yet\, in the 1D limit fluctuations preclude important technological use\, particularly of superconductors. In contrast\, high-Tc superconductors in 2D/3D are not precluded by fluctuations\, but lack a fundamental theory\, making prediction and engineering of their properties very difficult. In this talk we will present  work in progress on combining the advantages of 1D systems with those of higher-dimensional ones\, by advancing the theory of quasi-1D electrons coupled to an electron bath. We will focus on two aspects in particular:  (1) How to enable a new state of matter\, 1D electrons with true superconducting order\, by using fluctuations from a coherent electronic reservoir. (2) A new approach for the deliberate engineering of superconducting systems with properties computable\, and thus optimisable\, ab-initio\, i.e. from their microscopic properties. The use of hard-core bosons at this first stage allows us to rigorously validate our approach\, which yields insight into the physics of dimensional crossover in strongly correlated many-body systems.\n 
URL:https://tqmatter.org/event/cmt-seminar-adrian-kantian-gunnar-bollmark-1d-electrons-coupled-to-reservoirs-towards-new-systems-of-correlated-quantum-matter-and-novel-devices/
LOCATION:NORDITA // South  (Meeting Room 112.006B)\, Roslagstullsbacken 23\, Stockholm\, 106 91\, Sweden
CATEGORIES:Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Stockholm:20191001T150000
DTEND;TZID=Europe/Stockholm:20191001T170000
DTSTAMP:20260501T193307
CREATED:20190930T112341Z
LAST-MODIFIED:20190930T112341Z
UID:1755-1569942000-1569949200@tqmatter.org
SUMMARY:[Group Meeting] Sahar Pakdel
DESCRIPTION:Sahar Pakdel\, Aarhus University (Denmark) \nTitle: Exploring 2D-materials in synergy with experimentalists!”.\n\nAbstract: I will be talking about my experience studying some 2D systems with experimentalists. Specifically I will stress what I consider as the need for flexibility in the theory side while working on systems that are measured at the same time\, in comparison with exploring well-presented data.
URL:https://tqmatter.org/event/group-meeting-sahar-pakdel/
CATEGORIES:Group Meetings,Talks
END:VEVENT
END:VCALENDAR