Abstract
We demonstrated and analyzed the smooth microwave-driven transition of a superconducting bridge made from Hf into its normal state at bath temperatures below the critical temperature of Hf (Tc ≈ 380 mK). The bridge is integrated on a silicon chip with both the 600-700 GHz double-slot antenna and the 1.5-GHz CPW quarter-wave resonator (Q-factor ∼104) made from 100-nm Nb film. The experimental bridge was sized 2.5 um by 2.5 um by 50 nm and tested at temperatures down to 50 mK. Similar to the technique of MKID, we measured the dependence of transmission S21 on microwave power at the bottom of the resonance curve. It was found that the microwave power absorbed in the bridge fits to the model of hot electron gas, P∼Te6-Tph6. The internal NEP down to ≈10−18 W/⎷Hz is estimated due to thermal noise at the optimum electron gas temperature, Te ≈ 320 mK. The NEP can be scaled down below ≈10−19 W/√Hz via reasonable reduction of the bridge volume. The new detector circuit is suitable for integration within a large imaging array exploiting the FDM-readout.
Highlights
The monolithic bolometers are of great interest due to their mechanical and electrical stability
A low-noise measurement of the DC impedance is rather difficult, not to mention need in costly SQUID-amplifiers. This is why the readout of such electron gas impedance at a microwave frequency can be beneficial, especially for the implementation of array detectors using the method of wide-band frequency division multiplexing (FDM) [6,7]
Referring to the hot electron gas model of Hf described in paper [3], we have fitted the bias power absorbed by the bridge in our experiment, PB, to the electron temperature, Te, using the following formula
Summary
The monolithic bolometers are of great interest due to their mechanical and electrical stability. A low-noise measurement of the DC (lowfrequency) impedance is rather difficult, not to mention need in costly SQUID-amplifiers This is why the readout of such electron gas impedance at a microwave frequency can be beneficial, especially for the implementation of array detectors using the method of wide-band frequency division multiplexing (FDM) [6,7]. An FDM system has to be designed using one of the existing RF standards (for example, 50-Ω) and can use off-shelf GHz-range microwave amplifiers Another benefit of an RF standard is the ultimate accuracy of design in respect to the circuit stability.
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