Microwave spectroscopy of the Schmid transition
Aug 30, 20235 pages
Published in:
- Phys.Rev.B 109 (2024) 15, 155431
- Published: Apr 15, 2024
e-Print:
- 2308.16072 [cond-mat.supr-con]
DOI:
- 10.1103/PhysRevB.109.155431 (publication)
View in:
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Abstract: (APS)
Schmid transition was introduced first as a superconductor-insulator transition in the zero-frequency response of a shunted Josephson junction in equilibrium at zero temperature. As it is typical for a quantum impurity problem, at finite frequencies the transition is broadened to a crossover. Modern attempts to find Schmid transition rely on finite-frequency measurements of a quantum circuit. We predict the frequency dependence of the admittance and reflection phase shift for a high-impedance transmission line terminated by a Josephson junction for a wide variety of devices, from a charge qubit to a transmon. Our results identify the circuit parameters needed for the experimental observation of universal scaling of the responses with frequency. On the insulating side of the transition, the full crossover from weak to strong coupling can only be observed in a transmon. On the contrary, observation of such crossover on the superconducting side of the transition is possible only with the charge qubit. The frequency dependence gets weaker and vanishes upon approaching the Schmid transition from either side.Note:
- 6+5 pages, 2 figures
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Figures(2)
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