Speaker
Prof.
Francesco Giazotto
(Scuola Normale Superiore)
Description
The Josephson effect [1] represents perhaps the prototype of
macroscopic phase coherence and is at the basis of the most
widespread interferometer, i.e., the superconducting quantum
interference device (SQUID). Yet, in analogy to electric
interference, Maki and Griffin [2] predicted in 1965 that
thermal current flowing through a temperature-biased
Josephson tunnel junction is a stationary periodic function
of the quantum phase difference between the superconductors.
In this scenario, a temperature-biased SQUID would allow
heat currents to interfere thus implementing the thermal
version of the electric Josephson interferometer.
In this talk I will initially report the first experimental realization of such a heat interferometer [3]. We investigate heat exchange between two normal metal electrodes kept at different temperatures and tunnel-coupled to each other through a thermal device in the form of a DC-SQUID. Heat transport in the system is found to be phase dependent, in agreement with the original prediction. After this initial demonstration, we have extended the concept of the heat interferometry to various other devices and functionalities, implementing the first quantum `diffractor’ for thermal flux [4, 5], the realization of the first balanced Josephson heat modulator [6], and an ultra-efficient low-temperature hybrid `heat current rectifier’ [7, 8], thermal counterpart of the well-known electric diode. In the latter, we demonstrate temperature differences exceeding 60 mK between the forward and reverse thermal bias configurations [9]. This structure offers a remarkably large heat rectification ratio up to about 140 and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale. Finally, I will conclude by showing the realization of a fully superconducting heat modulator based on the first tunable „0-π“ thermal Josephson junction.
References
[1] B. D. Josephson, Phys. Lett. 1, 251 (1962).
[2] K. Maki and A. Griffin, Phys. Rev. Lett. 15, 921 (1965).
[3] F. Giazotto and M. J. Martínez-Pérez, Nature 492, 401 (2012).
[4] F. Giazotto, M. J. Martínez-Pérez, and P. Solinas, Phys. Rev B 88, 094506
(2013).
[5] M. J. Martínez-Pérez and F. Giazotto, Nat. Commun. 5, 3579 (2014).
[6] A. Fornieri, C. Blanc, R. Bosisio, S. D'Ambrosio, and F. Giazotto, Nat. Nanotechnol. 11, 258 (2016).
[7] M. J. Martínez-Pérez and F. Giazotto, Appl. Phys. Lett. 102, 182602 (2013).
[8] F. Giazotto and F. S. Bergeret, Appl. Phys. Lett. 103, 242602 (2013).
[9] M. J. Martínez-Pérez, A. Fornieri, and F. Giazotto, , Nat. Nanotechnol. 10, 303 (2015).
In this talk I will initially report the first experimental realization of such a heat interferometer [3]. We investigate heat exchange between two normal metal electrodes kept at different temperatures and tunnel-coupled to each other through a thermal device in the form of a DC-SQUID. Heat transport in the system is found to be phase dependent, in agreement with the original prediction. After this initial demonstration, we have extended the concept of the heat interferometry to various other devices and functionalities, implementing the first quantum `diffractor’ for thermal flux [4, 5], the realization of the first balanced Josephson heat modulator [6], and an ultra-efficient low-temperature hybrid `heat current rectifier’ [7, 8], thermal counterpart of the well-known electric diode. In the latter, we demonstrate temperature differences exceeding 60 mK between the forward and reverse thermal bias configurations [9]. This structure offers a remarkably large heat rectification ratio up to about 140 and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale. Finally, I will conclude by showing the realization of a fully superconducting heat modulator based on the first tunable „0-π“ thermal Josephson junction.
References
[1] B. D. Josephson, Phys. Lett. 1, 251 (1962).
[2] K. Maki and A. Griffin, Phys. Rev. Lett. 15, 921 (1965).
[3] F. Giazotto and M. J. Martínez-Pérez, Nature 492, 401 (2012).
[4] F. Giazotto, M. J. Martínez-Pérez, and P. Solinas, Phys. Rev B 88, 094506
(2013).
[5] M. J. Martínez-Pérez and F. Giazotto, Nat. Commun. 5, 3579 (2014).
[6] A. Fornieri, C. Blanc, R. Bosisio, S. D'Ambrosio, and F. Giazotto, Nat. Nanotechnol. 11, 258 (2016).
[7] M. J. Martínez-Pérez and F. Giazotto, Appl. Phys. Lett. 102, 182602 (2013).
[8] F. Giazotto and F. S. Bergeret, Appl. Phys. Lett. 103, 242602 (2013).
[9] M. J. Martínez-Pérez, A. Fornieri, and F. Giazotto, , Nat. Nanotechnol. 10, 303 (2015).
Primary author
Prof.
Francesco Giazotto
(Scuola Normale Superiore)