Figure 1

Experimental setup. (a) Internal circuit diagram of the TES system, consisting of the TES photon detector and its DC-SQUID readout. The TES photon detector is mounted on a 100-mK cold stage chilled by an adiabatic demagnetization refrigerator (ADR). The TES current \(I_{\text{TES}}\) is readout by DC-SQUID electronics and transferred proportionally to a voltage output \(V_{\text{out}}\). (b) Blinding and fake signal power is controlled by variable attenuators (Att), combined at a \(50\!:\!50\) fiber-optic beam splitter (BS), measured by an optical power meter (PM), and applied to the TES system under test. Its output voltage \(V_{\text{out}}\) is recorded and analyzed by a data acquisition module (DAQ) connected to a computer (PC)