High-quality superconducting tantalum resonators with beta phase defects
Abstract
For practical superconducting quantum processors, orders of magnitude improvement in coherence is required, motivating efforts to optimize hardware design and explore new materials. Among the latter, the coherence of superconducting transmon qubits has been shown to improve by forming the qubit capacitor pads from α-tantalum, avoiding the metastable β-phase that forms when depositing tantalum at room temperature, and has been previously identified to be a source of microwave losses. In this work, we show lumped element resonators containing β-phase tantalum in the form of inclusions near the metal–substrate interface with internal quality factors (Qi) up to 5.0 ± 2.5×106 in the single photon regime. They perform at least as good as resonators with no sign of the β-phase in x-ray diffraction and thermal quasi-particle loss. Our results indicate that small concentrations of β-phase can be beneficial, enhancing critical magnetic fields and potentially, for improving coherence in tantalum-based superconducting circuits.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (19)
Ritika Dhundhwal
IQMT, Karlsruhe Institute of Technology 1 , 76131 Karlsruhe,
Haoran Duan
INT, Karlsruhe Institute of Technology 2 , 76131 Karlsruhe,
Lucas Brauch
IQMT, Karlsruhe Institute of Technology 1 , 76131 Karlsruhe,
Soroush Arabi
IQMT, Karlsruhe Institute of Technology 1 , 76131 Karlsruhe,
Dirk Fuchs
Amir-Abbas Haghighirad
Alexander Welle
Florentine Scharwaechter
Physics Institute 1, University of Stuttgart 6 , 70569 Stuttgart,
Sudip Pal
Physics Institute 1, University of Stuttgart 6 , 70569 Stuttgart,
Marc Scheffler
Physics Institute 1, University of Stuttgart 6 , 70569 Stuttgart,
José Palomo
Laboratoire de Physique de l'Ecole normale supérieure 7 , 75005 Paris,
Zaki Leghtas
Laboratoire de Physique de l'Ecole normale supérieure 7 , 75005 Paris,
Anil Murani
Alice & Bob 8 , 53 Bd du Général Martial Valin, Paris 75015,
Horst Hahn
IQMT, Karlsruhe Institute of Technology 1 , 76131 Karlsruhe,
Jasmin Aghassi-Hagmann
INT, Karlsruhe Institute of Technology 2 , 76131 Karlsruhe,
Christian Kübel
Wulf Wulfhekel
Ioan M. Pop
Thomas Reisinger
IQMT, Karlsruhe Institute of Technology 1 , 76131 Karlsruhe,