Statistical properties of environmental and intrinsic decoherence*

In addition to providing a versatile platform for quantum information and quantum optics applications, the utilization of superconducting qubits as quantum sensors has emerged as an active area of research (see Refs. 1--3 among others). Superconducting qubits are sensitive to both intrinsic and environmental [4] perturbations that induce dephasing and relaxation. In this talk we present experimental data on time-dependent fluctuations of the properties of multiple transmon qubits spanning up to several days. We analyze histograms and Allan plots of energy relaxation time, coherence time, and frequency jumps. The method enables direct tests of specific noise hypotheses [5,6]. The aims of our study are to: 1) define the minimum required sampling time to accurately capture system performance and, 2) separate decoherence mechanisms intrinsic to the circuit versus environmental factors. For the latter we implement added thermal noise within the dilution refrigerator measurement system as a diagnostic resource [7].

[1] K. Serniak, et al. Phys. Rev. Applied 12, 014052 (2019)

[2] S. Schlör et al. Phys. Rev. Lett. 123, 190502 (2019)

[3]  R.T. Gordon, et al. Appl. Phys. Lett. 120, 074002 (2022)

[4] Vepsäläinen, et al. Nature 584, 551–556 (2020)

[5] Burnett, J.J. et al. npj Quantum Inf. 5, 54 (2019).

[6] K. Li, et al. IEEE Trans. Appl. Supercond., 33, 1, (2023)

[7] S. Simbierowicz, et al. Rev. Sci. Instrum.  92 (3): 034708 (2021)