2016/09/30 by Alexander Bilmes, Sebastian Zanker, Andreas Heimes +6
Computer Science · Physics and Astronomy · #Coherence (philosophical gambling strategy) #Condensed matter physics #Josephson effect #Physics #Physics of Superconductivity and Magnetism #Pi Josephson junction #Quantum #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum decoherence #Quantum mechanics #Quantum tunnelling #Quasiparticle #Qubit #Superconducting quantum computing #Superconducting tunnel junction #Superconductivity #Tunnel junction #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.96.064504
published as Phys. Rev. B 96, 064504 (2017)
openalex publication_date 2017/08/03 · arxiv created 2017/08/17 · arxiv updated 2017/08/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The sensitivity of superconducting qubits allows for spectroscopy and coherence measurements on individual two-level systems present in the disordered tunnel barrier of an Al/AlOx/Al Josephson junction. We report experimental evidence for the decoherence of two-level systems by Bogoliubov quasiparticles leaking into the insulating AlOx barrier. We control the density of quasiparticles in the junction electrodes either by the sample temperature or by injecting them using an on-chip dc superconducting quantum interference device driven to its resistive state. The decoherence rates were measured by observing the two-level system's quantum state evolving under application of resonant microwave pulses and were found to increase linearly with quasiparticle density, in agreement with theory. This interaction with electronic states provides a noise and decoherence mechanism that is relevant for various microfabricated devices such as qubits, single-electron transistors, and field-effect transistors. The presented experiments also offer a possibility to determine the location of the probed two-level systems across the tunnel barrier, providing clues about the fabrication step in which they emerge.