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Title: Radiation power and linewidth of a semifluxon-based Josephson oscillator

We demonstrate a high-frequency generator operating at ∼200 GHz based on flipping a semifluxon in a Josephson junction of moderate normalized length. The semifluxon spontaneously appears at the π discontinuity of the Josephson phase artificially created by means of two tiny current injectors. The radiation is detected by an on-chip detector (tunnel junction). The estimated radiation power (at the detector) is ∼8 nW and should be compared with the dc power of ∼100 nW consumed by the generator. The measured radiation linewidth, as low as 1.1 MHz, is typical for geometrical (Fiske) resonances, although we tried to suppress such resonances by placing well-matched microwave transformers at its both ends. Making use of a phase-locking feedback loop, we are able to reduce the radiation linewidth to less than 1 Hz measured relative to the reference oscillator and defined just by the resolution of our measurement setup.
Authors:
; ;  [1] ; ; ; ;  [2]
  1. Kotel'nikov Institute of Radioengineering and Electronics RAS, Mokhovaya 11, 125009 Moscow (Russian Federation)
  2. Physikalisches Institut and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen (Germany)
Publication Date:
OSTI Identifier:
22283154
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPARATIVE EVALUATIONS; ELECTRIC CURRENTS; JOSEPHSON JUNCTIONS; LINE WIDTHS; MICROWAVE RADIATION; OSCILLATORS; POSTULATED PARTICLES; RESONANCE; SUPERCONDUCTIVITY; SUPERCONDUCTORS; TRANSFORMERS; TUNNEL EFFECT