Schwinger effect in superconductors: a discovery by CnrNano and UniGe

Foto: The Sauter-Schwinger effect in a BCS superconductor


Pisa - 02.04.2021 - Schwinger effect in superconductors: a discovery by CnrNano and UniGe
Francesco Giazotto (Cnr-Nano) together with Paolo Solinas, Andrea Amoretti of the Physics Department of the University of Genoa have discovered that the Sauter-Schwinger effect - the creation of electron-positron pairs by a strong electric field - could finally be realised in a regular low-temperature superconducting material. The research appears as the cover story on the journal Physical Review Letters.

Giazotto, working at the NEST Laboratory of the Scuola Normale Superiore and Cnr-Nano, Solinas and Amoretti have discovered how it is possible to generate pairs of quasi-particles in superconducting materials by applying high electric fields.
In the 1950s the physicist Julian Schwinger predicted that it was possible to create an electron-positron pair from vacuum, through the application of a very intense electric field. So far this prediction has not found experimental verification, due to the very intense electric fields required (~ 10^18 V / m) which are not yet accessible in physics laboratories. The new discovery made by the team shows that a similar effect can occur in superconducting materials, under the action of electric fields that can be created in the laboratory.
"Our study shows that an electrostatic field can generate two coherent excitations from the superconducting ground-state condensate" says Giazotto. "Differently from the dissipative thermal excitation, these form a new macroscopically coherent and dissipationless state. We also discuss how the superconducting state is weakened by the creation of this kind of excitations".
In addition to shedding a different light and suggesting a method for the experimental verification of the Sauter-Schwinger effect, these results pave the way to the understanding and exploitation of the interaction between superconductors and electric fields.



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