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Title: Probing the density of states of two-level tunneling systems in silicon oxide films using superconducting lumped element resonators

We have investigated dielectric losses in amorphous silicon oxide (a-SiO) thin films under operating conditions of superconducting qubits (mK temperatures and low microwave powers). For this purpose, we have developed a broadband measurement setup employing multiplexed lumped element resonators using a broadband power combiner and a low-noise amplifier. The measured temperature and power dependences of the dielectric losses are in good agreement with those predicted for atomic two-level tunneling systems (TLS). By measuring the losses at different frequencies, we found that the TLS density of states is energy dependent. This had not been seen previously in loss measurements. These results contribute to a better understanding of decoherence effects in superconducting qubits and suggest a possibility to minimize TLS-related decoherence by reducing the qubit operation frequency.
Authors:
 [1] ;  [2] ; ; ;  [3] ; ; ; ;  [1] ;  [1] ;  [4]
  1. Physikalisches Institut, Karlsruher Institut für Technologie, Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe (Germany)
  2. (Germany)
  3. Institut für Mikro- und Nanoelektronische Systeme, Karlsruher Institut für Technologie, Hertzstraße 16, D-76187 Karlsruhe (Germany)
  4. (Russian Federation)
Publication Date:
OSTI Identifier:
22399119
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 2; Other Information: (c) 2015 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; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMPLIFIERS; DENSITY OF STATES; DIELECTRIC MATERIALS; ENERGY DEPENDENCE; MICROWAVE RADIATION; NOISE; OPERATION; PROBES; QUBITS; RESONATORS; SILICON OXIDES; SUPERCONDUCTIVITY; THIN FILMS; TUNNEL EFFECT