Tunable impedance environment for quantum phase slip experiments

Tunneling of magnetic vortices through a thin superconducting nanowire, i.e. quantum phase slips (QPS), can cause an insulating transition instead of the typical zero resistance state. This phenomenon is dual to Cooper pair tunneling in a Josephson junction with quantum conjugate variables the phase and the charge exchanged. The QPS nanowire may allow the realization of a very precise quantum current standard. Although the experimental realization of coherent QPS was reported [1], only weak reverse Shapiro effect-like features in superconducting nanowires were observed so far [2].

Using our millikelvin-operational silicon MOSFET platform [3], we realize an integrated tunable impedance environment for ultra-thin TiN and NbN superconducting nanowires. We present experimental QPS data, compare it with recent theoretical predictions [4], and determine the effect of the cryogenic microwave background on a QPS system [5].

The research is supported by the EU H2020 grants No 862660 & 824109 and the Academy of Finland (Centre of Excellence program: projects 336817 & 312294).  

[1] Nature 484, 355–358 (2012)

[2] Phys. Rev. Lett. 109, 187001 (2012); App. Phys. Lett., 114, 242601 (2019)

[3] Appl. Phys. Lett. 118, 164002 (2021)

[4] Phys. Rev. B 102, 144509 (2020)

[5] Phys. Rev. B 85, 012504 (2012)