7 papers
Readout failures in superconducting qubits due to TLS-defects in tunnel junctions
J. Lisenfeld, A. K. Händel, A. Bilmes +1
Material defects give rise to parasitic two-level systems (TLS) which present a major source of decoherence in superconducting qubits. Here, we study a strongly coupled TLS that re…
Mapping the positions of Two-Level-Systems on the surface of a superconducting transmon qubit
Jürgen Lisenfeld, Alexander K. Händel, Etienne Daum +3
The coherence of superconducting quantum computers is severely limited by material defects that create parasitic two-level-systems (TLS). Progress is complicated by lacking underst…
Benchmarking the quality of multiplexed qubit readout beyond assignment fidelity
Andras Di Giovanni, Adrian Skasberg Aasen, Jürgen Lisenfeld +3
The accurate measurement of quantum two-level objects (qubits) is crucial for developing quantum computers. Over the last decade, the measure of choice for benchmarking readout rou…
Gradiometric, Fully Tunable C-Shunted Flux Qubits
Benedikt Berlitz, Alexander Konstantin Händel, Etienne Daum +2
Fully tunable flux qubits offer in-situ and independent controls of their energy potential asymmetry and tunnel barrier, making them versatile tools for quantum computation and the…
Investigation of Parasitic Two-Level Systems in Merged-Element Transmon Qubits
Etienne Daum, Benedikt Berlitz, Steffen Deck +2
In conventional transmon qubits, decoherence is dominated by a large number of parasitic two-level systems (TLS) residing at the edges of its large area coplanar shunt capacitor an…
Dielectric waveguide setup tested with a superconducting millimeter-wave Fabry-Pérot interferometer at milli-Kelvin temperatures
Jakob Lenschen, Rosalie Labbe, Nils Drotleff +4
We propose and test a cryogenic setup comprising dielectric waveguides for mm-wave frequencies in the range of 75-110 GHz and temperatures down to 10 mK. The targeted applications…