YQI Talk - Kungang Li - UMD

Event time: 
Thursday, May 2, 2024 - 11:00am to 12:00pm
YQI Researchers
YQI Seminar Room See map
Event description: 

Energy relaxation time fluctuations in transmon qubits with different superconducting gaps 

Superconducting qubits are an ideal platform for quantum computing and the relaxation time Thas increased in recent years. We have repeatedly measured the behavior of Al/AlOx/Al transmons that have electrodes with different superconducting gaps in a 3-D cavity and observed significant fluctuations. In our devices, the base electrode was formed from nominally pure aluminium while the counter electrode was formed from oxygen-doped aluminium. The measurement of T1 varied from 100 to 300 μs under low temperature and the maximum T1 of the transmon observed was 310 μs at 20 mK. A device with a thin doped-Al base electrode and thick pure Al counter electrode showed Tfluctuations of a similar size with maximum T1 values over 200 μs. Measurements of the fluctuations versus temperature reveal that the standard deviation of T1 is proportional to T1. I proposed a mechanism for exploring the T1 fluctuation data and discuss the possible underlying cause of the Tfluctuations.

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