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Regular version of the site

Article

Relaxation of Nonequilibrium Quasiparticles in Mesoscopic Size Superconductors

Journal of Physics: Condensed Matter. 2018. Vol. 30. No. 343001. P. 1-16.
Arutyunov K. Yu., Chernyaev S. A., Karabassov T., Lvov D. S., Stolyarov V. S., Vasenko A. S.

Rapid development of micro- and nanofabrication methods have provoked interest
and enabled experimental studies of electronic properties of a vast class of (sub)micrometersize
solid state systems. Mesoscopic-size hybrid structures, containing superconducting
elements, have become interesting objects for basic research studies and various applications,
ranging from medical and astrophysical sensors to quantum computing. One of the
most important aspects of physics, governing the behavior of such systems, is the finite
concentration of nonequilibrium quasiparticles, present in a superconductor even well below
the temperature of superconducting transition. Those nonequilibrium excitations might limit
the performance of a variety of superconducting devices, like superconducting qubits, singleelectron
turnstiles and microrefrigerators. On the contrary, in some applications, like detectors
of electromagnetic radiation, the nonequilibrium state is essential for their operation. It
is therefore of vital importance to study the mechanisms of nonequilibrium quasiparticle
relaxation in superconductors of mesoscopic dimensions, where the whole structure can be
considered as an ‘interface’. At early stages of research the problem was mostly studied
in relatively massive systems and at high temperatures close to the critical temperature of
a superconductor. We review the recent progress in studies of nonequilibrium quasiparticle
relaxation in superconductors including the low temperature limit. We also discuss the open
physical questions and perspectives of development in the field.