Table 1 Summary of the main parameters extracted from qubit and thin film measurements.

From: Microscopic relaxation channels in materials for superconducting qubits

Deposition

Sputtered

HiPIMS opt

HiPIMS norm

T1 (μs)

56 ± 12

33 ± 2

17 ± 9

RRR

8.9 ± 0.1

5.0 ± 0.2

2.9 ± 0.1

Tc (K)

9.0 ± 0.1

8.6 ± 0.1

8.1 ± 0.1

GSA (nm2)

1140 ± 70

500 ± 50

180 ± 30

Nb

61 ± 3

64 ± 3

45 ± 2

NbOx

15.1 ± 0.2

16 ± 0.3

20.4 ± 0.8

NbO

0 ± 2

0 ± 1

5 ± 1

NbO2

3.1 ± 0.4

3.5 ± 0.2

10 ± 2

Nb2O5

20 ± 1

15.9 ± 0.8

19 ± 2

Suboxide

19 ± 2

20 ± 1

36 ± 2

  1. For T1, we report the average and standard deviation between the three rounds for each film. RRR and Tc measurement errors are reported, as well as the uncertainty on the estimates for the GSA, which is the mean grain surface area. The numbers for the different oxidation states of Nb are relative concentrations integrated over the 20 nm in the depth profiles of Fig. 3, expressed in percentages. The errors were calculated for each depth step, and summed in quadrature and weighted according to the total measured signal for each oxidation state. Suboxide is the sum of the relative concentrations of NbOx, NbO, and NbO2.
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