BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Quantum Fluctuation Phenomena in Quasi-1D Superconductors DTSTART;VALUE=DATE-TIME:20190622T100000Z DTEND;VALUE=DATE-TIME:20190622T103000Z DTSTAMP;VALUE=DATE-TIME:20260314T141600Z UID:indico-contribution-40-214@cern.ch DESCRIPTION:Speakers: Konstantin Arutyunov (National Research University H igher School of Economics\, Moscow Institute of Electronics and Mathematic s\, 101000\, Moscow\, Russia\; P.L. Kapitza Institute for Physical Problem s RAS\, 119334\, Moscow\, Russia.)\nSuperconducting properties of metallic nanowires can be entirely different from those of bulk superconductors be cause of the dominating role played by thermal and quantum fluctuations of the order parameter [1]. Fundamental attributes of superconductivity such as zero resistivity\, persistent currents in closed loops\, energy gap in excitation spectra can be drastically violated by fluctuations. Quasi-one -dimensional superconducting channels host sound-like plasma modes propaga ting along the sample which are associated with fluctuations of the phase of the superconducting order parameter [2]. Interaction between these elec tromagnetic excitations and charge carriers affects the electron density o f states (DOS) [3]. Here we report the experimental study of I-V charact eristics of tunnel S1-I-S2 junctions\, where superconducting S2 electrode is a thin nanowire in the regime of quantum fluctuations. The observed bro adening of the I-V dependencies at the gap edge is interpreted as the reno rmalization of DOS. The results are in reasonable agreement with the model [3]\, taking into consideration plasma modes in quasi-one-dimensional sup erconductors.\n\n\n[1] Arutyunov K. Yu.\, Golubev D. S. \, Zaikin A. D. 20 08 Physics Reports 464 1.\n\n[2] Mooij J.E. and G. Schön\, 1985 Phys. R ev. Lett. 55 114.\n\n[3] Radkevich A. A.\, Semenov A. G.\, Zaikin A. D. 2 017 Phys. Rev. B 96 085435.\n\nhttps://indico.unina.it/event/18/contribut ions/214/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/214/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum fluctuations and phase coherence in superconducting nanowi res DTSTART;VALUE=DATE-TIME:20190622T093000Z DTEND;VALUE=DATE-TIME:20190622T094500Z DTSTAMP;VALUE=DATE-TIME:20260314T141600Z UID:indico-contribution-40-248@cern.ch DESCRIPTION:Speakers: Alexey Radkevich (Lededev Physical Institute)\nQuant um behavior of superconducting nanowires may essentially depend on the emp loyed experimental setup. Here we investigate a setup that enables passing equilibrium supercurrent across an arbitrary segment of the wire without restricting fluctuations of its superconducting phase. The low temperature physics of the system is determined by a combined effect of collective so und-like plasma excitations and quantum phase slips. At $T=0$ the wire exh ibits two quantum phase transitions\, both being controlled by the dimensi onless wire impedance $g$. While thicker wires with $g>16$ stay supercondu cting\, in thinnest wires with $g<2$ the supercurrent is totally destroyed by quantum fluctuations. The intermediate phase with $2\n\nhttps://indico .unina.it/event/18/contributions/248/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/248/ END:VEVENT BEGIN:VEVENT SUMMARY:Coulomb drag effect in a system of coupled superconducting nanowir es. DTSTART;VALUE=DATE-TIME:20190622T094500Z DTEND;VALUE=DATE-TIME:20190622T100000Z DTSTAMP;VALUE=DATE-TIME:20260314T141600Z UID:indico-contribution-40-249@cern.ch DESCRIPTION:Speakers: Alexandr Latyshev (Higher school of economics\, Leb edev Physical institute.)\nAl low temperatures superconducting nanowires d emonstrate wide range of intriguing physical phenomena. Of particular inte rest are those that are due to quantum phase slips (QPS)\, as an example t he change in nonlocal transport in superconducting nanowires. This work is devoted to studying the interplay between Coulomb drag effect and QPS in a system of coupled superconducting nanowires. It is important that QPS ge nerate plasmon waves that propagate in separating wires and QPS in one wir e affect on the physical properties of another.\n\nhttps://indico.unina.it /event/18/contributions/249/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/249/ END:VEVENT BEGIN:VEVENT SUMMARY:Superconductor-insulator quantum transition in extra-long\, one-di mensional chains of Josephson junctions DTSTART;VALUE=DATE-TIME:20190622T090000Z DTEND;VALUE=DATE-TIME:20190622T093000Z DTSTAMP;VALUE=DATE-TIME:20260314T141600Z UID:indico-contribution-40-209@cern.ch DESCRIPTION:Speakers: Alexey Bezryadin (University of Illinois\, Departmen t of Physics\, Urbana\, IL 61801)\nA quantum phase transition (QPT) repres ents a discontinuous change of the ground state of an extended\, ideally i nfinite\, system. Such transitions occur at zero temperature and they are driven by tuning a parameter in the Hamiltonian. If an effective Hamiltoni an is such that it includes some temperature-dependent parameters\, then a temperature-controlled quantum transition (TC-QPT) can be expected. Here we present a TC-QPT between superconducting and insulating regimes in a ch ain of weakly coupled superconducting islands. The transition appears at a temperature where the Josephson energy equals the effective Coulomb charg ing energy\, defined by the electric capacitance between the islands. The insulating state is manifested by a resistance peak\, characterized by an exponential growth of resistance with cooling\, while the superconducting state is represented by an exponential drop of the resistance with cooling . A scaling analysis\, which takes into account the temperature-dependent critical parameter of the observed TC-QPT\, is presented. The temperature dependence of the QPT critical point comes about because the Josephson cou pling energy depends on the BCS energy gap\, which is temperature dependen t.\n\nhttps://indico.unina.it/event/18/contributions/209/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/209/ END:VEVENT END:VCALENDAR