title: Coherent Excited States in Superconductors due to a Microwave Field.
abstract: We describe theoretically the depairing effect of a microwave field on diffusive s-wave superconductors. The ground state of the superconductor is altered qualitatively in analogy to the depairing due to a dc current. In contrast to dc depairing, the density of states acquires, for microwaves with frequency ω_{0}, steps at multiples of the photon energy Δ±nℏω_{0} and shows an exponential-like tail in the subgap regime. We show that this ac depairing explains the measured frequency shift of a superconducting resonator with microwave power at low temperatures.
authors: Moscow State Pedagogical University, 1 Malaya Pirogovskaya Street, Moscow 119992, Russia.|Moscow Institute of Physics and Technology, Dolgoprudny, Moscow 141700, Russia.
authors: A V
authors: AV
authors: Semenov
authors: Moscow Institute of Physics and Technology, Dolgoprudny, Moscow 141700, Russia.|Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, 1(2), Leninskie gory, GSP-1, Moscow 119991, Russia.
authors: I A
authors: IA
authors: Devyatov
authors: Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.|SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands.
authors: P J
authors: PJ
authors: de Visser
authors: Moscow State Pedagogical University, 1 Malaya Pirogovskaya Street, Moscow 119992, Russia.|Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors: T M
authors: TM
authors: Klapwijk