title: Experimental Study of Spectral Properties of a Frenkel-Kontorova System.
abstract: We report on microwave emission from linear parallel arrays of underdamped Josephson junctions, which are described by the Frenkel-Kontorova (FK) model. Electromagnetic radiation is detected from the arrays when biased on current singularities (steps) appearing at voltages V(n)=Φ(0)(nc̅/L), where Φ(0)=2.07×10(-15)  Wb is the magnetic flux quantum, and c̅, L, and n are, respectively, the speed of light in the transmission line embedding the array, L its physical length, and n an integer. The radiation, detected at fundamental frequency c̅/2L when biased on different singularities, indicates shuttling of bunched 2π kinks (magnetic flux quanta). Resonance of flux-quanta motion with the small-amplitude oscillations induced in the arrays gives rise to fine structures in the radiation spectrum, which are interpreted on the basis of the FK model describing the resonance. The impact of our results on design and performances of new digital circuit families is discussed.
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Lucci
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Badoni
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Merlo
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Ottaviani
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Salina
authors.affiliation: Dipartimento di Fisica and MINAS Lab, Università di Roma Tor Vergata, 00133 Roma, Italy and INFN sezione "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cirillo
authors.affiliation: Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany and National University of Science and Technology MISIS, Leninsky prosp. 4, Moscow 119049, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Ustinov
authors.affiliation: Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Winkler