KIT | KIT-Bibliothek | Impressum | Datenschutz

Intrinsic decoherence in superconducting quantum circuits

Schlör, Steffen

Abstract:
Decoherence and parameter fluctuations are two of the mayor obstacles for solid-state quantum computing.
In this work, decoherence in superconducting qubits of the transmon type is investigated. For this purpose, a time-multiplexed measurement protocol was developed and applied in long-term measurements. The resulting simultaneous measurement of the qubit's relaxation and dephasing rate, as well as its resonance frequency enables analysis of correlations between these parameters. A spectral noise analysis complements these measurements. Together, the results agree well with the interacting defect model of two-level-systems and yield information about the microscopic origin of the intrinsic decoherence mechanisms in Josephson qubits.

Our measurements show inherent correlations between dephasing and fluctuations in qubit frequency on the timescale of seconds to days, which is attributed to the influence of individual defects, located close to conductor edges. Cross-correlation and spectral noise analysis confirm this interpretation and ascribe the source of fluctuation to interactions between thermal fluctuators and surface defects. ... mehr

Open Access Logo


Volltext §
DOI: 10.5445/IR/1000105563
Veröffentlicht am 05.02.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Physikalisches Institut (PHI)
Publikationstyp Hochschulschrift
Publikationsjahr 2020
Sprache Englisch
Identifikator KITopen-ID: 1000105563
Verlag Karlsruhe
Umfang IV, 125 S.
Abschlussart Dissertation
Fakultät Fakultät für Physik (PHYSIK)
Institut Physikalisches Institut (PHI)
Prüfungsdatum 20.12.2019
Referent/Betreuer Prof. A. V. Ustinov
Projektinformation DFG, DFG EIN, WE 4359/7-1
DFG, DFG INFRA, INST 121384/138-1 FUGG
Schlagwörter Qubit, Coherence, Two-Level-Systems, PSD, Superconductivity
KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft
KITopen Landing Page