Thermal and Residual Excited-State Population in a 3D Transmon Qubit
Author(s)
Jin, X. Y.; Gudmundsen, Theodore J.; Miloshi, J.; Yan, F.; Kamal, Archana; Sears, Adam P.; Hover, David J.; Slattery, Richard L.; Yoder, Jonilyn Longenecker; Orlando, Terry Philip; Gustavsson, Simon; Oliver, William D.; ... Show more Show less
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Remarkable advancements in coherence and control fidelity have been achieved in recent years with cryogenic solid-state qubits. Nonetheless, thermalizing such devices to their milliKelvin environments has remained a long-standing fundamental and technical challenge. In this context, we present a systematic study of the first-excited-state population in a 3D transmon superconducting qubit mounted in a dilution refrigerator with a variable temperature. Using a modified version of the protocol developed by Geerlings et al., we observe the excited-state population to be consistent with a Maxwell-Boltzmann distribution, i.e., a qubit in thermal equilibrium with the refrigerator, over the temperature range 35–150 mK. Below 35 mK, the excited-state population saturates at approximately 0.1%. We verified this result using a flux qubit with ten times stronger coupling to its readout resonator. We conclude that these qubits have effective temperature T_{eff}=35 mK. Assuming T[subscript eff] is due solely to hot quasiparticles, the inferred qubit lifetime is 108 μs and in plausible agreement with the measured 80 μs.
Date issued
2015-06Department
Lincoln Laboratory; Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Research Laboratory of ElectronicsJournal
Physical Review Letters
Publisher
American Physical Society
Citation
Jin, X. Y., et al. "Thermal and Residual Excited-State Population in a 3D Transmon Qubit." Phys. Rev. Lett. 114, 240501 (June 2015). © 2015 American Physical Society
Version: Final published version
ISSN
0031-9007
1079-7114