| AVS 66th International Symposium & Exhibition | |
| Materials and Processes for Quantum Information, Computing and Science Focus Topic | Monday Sessions |
| Session QS+EM+MN+NS-MoM |
| Session: | High Coherence Qubits for Quantum Computing |
| Presenter: | Jonas Bylander, Chalmers University of Technology, Sweden |
| Correspondent: | Click to Email |
We are engineering a superconducting quantum processor within the Wallenberg Center for Quantum Technology [1] in Sweden and the project OpenSuperQ [2] of the European Union's Flagship on Quantum Technology.
Here we will present our engineering approach for high-coherence superconducting quantum hardware. We have studied the temporal stability of relaxation and dephasing in transmon qubits [3]. Our qubits are made of aluminum on silicon; they have reached average T1 relaxation times of about 70 us. The T2* decoherence time, as measured in a Ramsey fringe, is practically relaxation-limited. By collecting statistics during measurements spanning several days, we reveal large fluctuations of qubit lifetimes – the standard deviation of T1 is about 15 us – and find that the cause of fluctuations is parasitic, near-resonant two-level-systems (TLS). Our statistical analysis shows consistency with an interacting-TLS model. Interacting TLS also cause low-frequency capacitance fluctuations, ultimately leading to frequency noise and dephasing of the qubit state. These discoveries are important for creating stable superconducting circuits suitable for high-fidelity quantum gates in quantum computing applications.
[1] www.wacqt.se
[2] www.opensuperq.eu
[3] J. J. Burnett, A. Bengtsson, M. Scigliuzzo, D. Niepce, M. Kudra, P. Delsing, and J. Bylander, “Decoherence benchmarking of superconducting qubits” arXiv:1901.04417