Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR 8502, F-91405 Orsay Cedex, France.
Phys Rev Lett. 2010 Oct 15;105(16):166801. doi: 10.1103/PhysRevLett.105.166801. Epub 2010 Oct 11.
Using a quantum detector, a superconductor-insulator-superconductor junction, we probe separately the emission and absorption noise in the quantum regime of a 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. By coupling a Josephson junction, biased above the superconducting gap, to the same resonant circuit, we directly measure the noise power of quasiparticles tunneling through the junction at two resonance frequencies. It exhibits a strong frequency dependence, consistent with theoretical predictions.
利用量子探测器超导-绝缘-超导结，我们分别探测了处于平衡态下超导共振电路量子区的发射和吸收噪声。在低温下，共振电路只表现出与零点波动相关的吸收噪声，而在较高温度下则会出现发射噪声。通过将偏置在超导能隙之上的约瑟夫森结耦合到相同的共振电路，我们直接测量了在两个共振频率下通过结的准粒子隧道的噪声功率。它表现出强烈的频率依赖性，与理论预测一致。
