Simbierowicz Slawomir, Vesterinen Visa, Milem Joshua, Lintunen Aleksi, Oksanen Mika, Roschier Leif, Grönberg Leif, Hassel Juha, Gunnarsson David, Lake Russell E
Bluefors Oy, Arinatie 10, 00370 Helsinki, Finland.
VTT Technical Research Centre of Finland Ltd., QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland.
Rev Sci Instrum. 2021 Mar 1;92(3):034708. doi: 10.1063/5.0028951.
We present a cryogenic microwave noise source with a characteristic impedance of 50 Ω, which can be installed in a coaxial line of a cryostat. The bath temperature of the noise source is continuously variable between 0.1 K and 5 K without causing significant back-action heating on the sample space. As a proof-of-concept experiment, we perform Y-factor measurements of an amplifier cascade that includes a traveling wave parametric amplifier and a commercial high electron mobility transistor amplifier. We observe system noise temperatures as low as 680 mK at 5.7 GHz corresponding to 1.5 excess photons. The system we present has immediate applications in the validation of solid-state qubit readout lines.
我们展示了一种特性阻抗为50Ω的低温微波噪声源，它可安装在低温恒温器的同轴线中。该噪声源的浴温可在0.1 K至5 K之间连续变化，而不会对样品空间产生显著的反作用加热。作为概念验证实验，我们对一个放大器级联进行了Y因子测量，该级联包括一个行波参量放大器和一个商用高电子迁移率晶体管放大器。我们在5.7 GHz频率下观测到系统噪声温度低至680 mK，对应1.5个过量光子。我们展示的系统在固态量子比特读出线路的验证中具有直接应用。
