Noise temperature and beam pattern of an NbN hot electron bolometer mixer at 5.25 THz

We report the measured sensitivities of a superconducting NbN hot electron bolometer (HEB) heterodyne receiver at 5.25 THz. Terahertz (THz) radiation is quasioptically coupled to a HEB mixer with a lens and a spiral antenna. Using a measurement setup with black body calibration sources and a beam splitter in vacuo, and an antireflection coated...

Noise in NbTiN, Al, and Ta Superconducting Resonators on Silicon and Sapphire Substrates

We present measurements of the frequency noise and resonance frequency temperature dependence in planar superconducting resonators on both silicon and sapphire substrates. We show, by covering the resonators with sputtered SiOx layers of different thicknesses, that the temperature dependence of the resonance frequency scales linearly with...

Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators

We study NbTiN resonators by measurements of the temperature dependent resonance frequency and frequency noise. Additionally, resonators are studied covered with SiOx dielectric layers of various thicknesses. The resonance frequency develops a nonmonotonic temperature dependence with increasing SiOx layer thickness. The increase in the noise is...

Influence of the direct response on the heterodyne sensitivity of hot electron bolometer mixers

We present a detailed experimental study of the direct detection effect in a small volume (0.15??m×1??m×3.5?nm) quasioptical NbN phonon cooled hot electron bolometer mixer at 673?GHz. We find that the small signal noise temperature, relevant for an astronomical observation, is 20% lower than the noise temperature obtained using 300 and 77?K...