ETD

Archivio digitale delle tesi discusse presso l'Università di Pisa

Tesi etd-09262017-171616


Tipo di tesi
Tesi di laurea magistrale
Autore
PUGLIA, CLAUDIO
URN
etd-09262017-171616
Titolo
Phase Coherent Josephson Thermal Router
Dipartimento
FISICA
Corso di studi
FISICA
Relatori
relatore Giazotto, Francesco
Parole chiave
  • superconductivity
  • SQUID
  • router
  • Josephson
  • coherent
  • thermal
Data inizio appello
18/10/2017
Consultabilità
Completa
Riassunto
Today while the electronic current at nanoscale has been widely studied in some materials and devices, the research on the heat currents are in a embryonic state. The new field of the Coherent Caloritronics studies the manipulation and the superconducting interference phenomenons of the heat currents.
This field has given birth to some devices like the heat interferometer [3] [4] and the thermal diode [1] [2] and with this work we will do another step to the complete control of the thermal currents.
The aim of this thesis is to acquire the control over heat currents at nanoscale and to observe the effect with temperature measurement on two metallic leads (Drains).
The router, consists of a Source tunnel-coupled with a Normal metal-Insulator-Superconductor (NIS) Josephson junction to the superconducting upper branch of the heat modulator, which is coupled through a Superconductor-Insulator-Superconductor (SIS) Josephson junction to a superconducting wire,
which is coupled though a NIS junction to the Drain1; instead the lower branch is tunnel-coupled (NIS) to the Drain2. The heat modulator is a Superconducting QUantum Interference Device (SQUID).
The main effect used to get the control over the currents was theorized by Maki and Griffin [5] [6] who found an analytical expression for the heat current through Josephson junction.
The expression have two terms, the former is the usual one, which follows the thermal gradient, and the
latter depends from the phase difference of the order parameter of superconductors. The first term is always bigger than the second one in order to follow the second law of thermodynamics. We can set this phase difference with the magnetic flux through the SQUID.
In the end, the device allows to control spatially the heat current, one of the fundamental requests of thermal logic.

[1] F. Giazotto M.J. Martinez-Pérez. The josephson heat interferometer.
[2] F. Giazotto M.J. Martinez-Pérez. A quantum diffractor for thermal flux, 2014.
[3] F. Giazotto M.J. Martinez-Pérez, A. Fornieri. Rectification of electronic heat current by a hybrid thermal diode, 2015.
[4] F. Giazotto M.J. Martinez-Pérez. Efficient phase-tunable josephson thermal rectifier, 2013.
[5] A. Griffin K. Maki. Entropy transport between two superconductors by journal electron tunnelling, Phys. Rev. Lett., 1965 .
[6] B. Nathanson G.D. Guttman D.J. Bergman, E. Ben-Jacob. Phys. Rev. B, 55(3849), 1997.
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