科研之友
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摘要
By coupling a quantum detector, a superconductor-insulator-superconductor junction, to a Josephson junction via a resonant circuit we probe the high-frequency properties, namely the ac complex admittance and the current fluctuations of the Josephson junction at the resonant frequencies. The admittance components show frequency-dependent singularities related to the superconducting density of states while the noise exhibits a strong frequency dependence, consistent with theoretical predictions. The circuit also allows us to probe separately the emission and absorption noise in the quantum regime of the superconducting resonant circuit at equilibrium. At low temperature the resonant circuit exhibits only absorption noise related to zero-point fluctuations, whereas at higher temperature emission noise is also present.
- 出版日期2012-2-27
