ORCID Profile
0000-0001-8605-4373
Current Organisation
Karlsruher Institut für Technologie
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: AIP Publishing
Date: 20-12-2010
DOI: 10.1063/1.3529457
Abstract: We use high-precision spectroscopy and detailed theoretical modeling to determine the form of the coupling between a superconducting phase qubit and a two-level defect. Fitting the experimental data with our theoretical model allows us to determine all relevant system parameters. We observe a strong qubit-defect coupling with a nearly vanishing longitudinal component. We quantitatively compare several existing theoretical models for the microscopic origin of two-level defects.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2015
DOI: 10.1038/NCOMMS7182
Abstract: Parasitic two-level tunnelling systems originating from structural material defects affect the functionality of various microfabricated devices by acting as a source of noise. In particular, superconducting quantum bits may be sensitive to even single defects when these reside in the tunnel barrier of the qubit’s Josephson junctions, and this can be exploited to observe and manipulate the quantum states of in idual tunnelling systems. Here, we detect and fully characterize a system of two strongly interacting defects using a novel technique for high-resolution spectroscopy. Mutual defect coupling has been conjectured to explain various anomalies of glasses, and was recently suggested as the origin of low-frequency noise in superconducting devices. Our study provides conclusive evidence of defect interactions with full access to the in idual constituents, demonstrating the potential of superconducting qubits for studying material defects. All our observations are consistent with the assumption that defects are generated by atomic tunnelling.
Publisher: American Physical Society (APS)
Date: 25-03-2010
Publisher: American Physical Society (APS)
Date: 03-12-2010
Publisher: American Physical Society (APS)
Date: 08-11-2019
Publisher: IOP Publishing
Date: 30-10-2019
Abstract: Amorphous solids show surprisingly universal behaviour at low temperatures. The prevailing wisdom is that this can be explained by the existence of two-state defects within the material. The so-called standard tunneling model has become the established framework to explain these results, yet it still leaves the central question essentially unanswered-what are these two-level defects (TLS)? This question has recently taken on a new urgency with the rise of superconducting circuits in quantum computing, circuit quantum electrodynamics, magnetometry, electrometry and metrology. Superconducting circuits made from aluminium or niobium are fundamentally limited by losses due to TLS within the amorphous oxide layers encasing them. On the other hand, these circuits also provide a novel and effective method for studying the very defects which limit their operation. We can now go beyond ensemble measurements and probe in idual defects-observing the quantum nature of their dynamics and studying their formation, their behaviour as a function of applied field, strain, temperature and other properties. This article reviews the plethora of recent experimental results in this area and discusses the various theoretical models which have been used to describe the observations. In doing so, it summarises the current approaches to solving this fundamentally important problem in solid-state physics.
Publisher: IOP Publishing
Date: 09-06-2011
Publisher: American Physical Society (APS)
Date: 25-10-2010
Publisher: American Physical Society (APS)
Date: 31-07-2015
Location: No location found
No related grants have been discovered for Jürgen Lisenfeld.