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[Fizinfo] Rok Zitko's talk next Monday (Sep 14)


Chronological Thread 
  • From: Andras Palyi <palyi AT mail.bme.hu>
  • To: FIZINFO AT lists.kfki.hu
  • Subject: [Fizinfo] Rok Zitko's talk next Monday (Sep 14)
  • Date: Wed, 9 Sep 2020 18:55:18 +0200

Dear Colleagues,

Next Monday the BME Exotic Quantum Phases seminar series continues with this
talk:

Speaker: Rok Zitko (Ljubljana)
Title: "Yu-Shiba-Rusinov states in superconducting island with finite
charging energy"
Abstract: below
Time: Sep 14 Monday, 14:15
Location: online in Teams

The link to join the talk in Teams:

https://teams.microsoft.com/l/meetup-join/19%3a8cc7e9ee6d1e483a864d41f638246643%40thread.tacv2/1599670191895?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22f8b27e90-dbca-4bb5-813c-d6415577ec35%22%7d

<https://teams.microsoft.com/l/meetup-join/19:8cc7e9ee6d1e483a864d41f638246643 AT thread.tacv2/1599670191895?context={%22Tid%22:%226a3548ab-7570-4271-91a8-58da00697029%22,%22Oid%22:%22f8b27e90-dbca-4bb5-813c-d6415577ec35%22}>

Best regards,
Andras Palyi

= = =

Abstract: "Recent advances in the fabrication of nanometer scale hybrid
semiconductor-superconductor devices as well as in the scanning tunneling
spectroscopy of adsorbate covered surfaces of superconductors have made
possible very detailed experimental studies of the old problem of
paramagnetic impurities in a superconducting host using local probes with
very high energy and spatial resolution. At the same time, improved
theoretical tools have been devised to reliably and accurately calculate the
excitation spectra of the corresponding quantum impurity problems with gapped
continuum electrons. These developments have enabled very stringent tests
between experiment and theory. The results demonstrate the importance to
describe the magnetic impurities as quantum objects with non-trivial internal
dynamics due to the coupling to their environment.

I will discuss the physics of bound states induced by the exchange
interaction between the magnetic impurities and the Bogoliubov quasiparticles
in superconductors, known as the Yu-Shiba-Rusinov states. They are observable
as spectroscopically sharp resonances in the tunneling spectra, located well
inside the superconducting gap for sufficiently strong exchange coupling. If
the superconductor is small and has a sizeable charging energy E_c, the
problem must be described using a model that allows tracking charge on the
superconductor. I will show that a pairing Hamiltonian with a charging term
admits a compact matrix-product-operator representation and can be reliably
solved using the density-matrix renormalization group (DMRG) techniques. I
will discuss how the properties of the system change as a function of the
ratio of the charging energy over the superconducting gap, E_c/Delta. The
method can be generalized to the situation with two superconducting islands
where two-channel Kondo physics can be explored."




  • [Fizinfo] Rok Zitko's talk next Monday (Sep 14), Andras Palyi, 09/09/2020

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