Ptitsina, N. G., Chulkova, G. M., & Gershenzon, E. M. (1995). Influence of the interference of electron-phonon and electron-impurity scattering on the conductivity of unordered Nb films. JETP, 80(5), 960–964.
Abstract: The temperature dependence of the resistivity of Nb thin films has been studied at T=4.2-300 K. It has been shown that quantum interference between electron-phonon and electron-impurity scattering determines the temperature dependence of the resistivity of the films investigated over a broad temperature range. The magnitude of the contribution of the electron-phonon-impurity,interference is described satisfactorily by the theory developed by Reizer and Sergeev {Zh. Eksp. Teor. Fiz. 92,2291 (1987) [Sov. Phys. JETP 65, 1291 (1987)l). The interaction constants of electrons with longitudinal and transverse phonons in Nb films have been determined for the first time by comparing the experimental data with the theory. The values of the constants obtained are consistent with the data on the inelastic electron-phonon scattering times in the films investigated. The contribution of the transverse phonons is dominant both in the interference correction to the resistivity and in the electron energy relaxation.
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Beck, M., Klammer, M., Rousseau, I., Gol’tsman, G. N., Diamant, I., Dagan, Y., et al. (2015). Probing superconducting gap dynamics with THz pulses. In CLEO (SM3H.3 (1 to 2)). Optical Society of America.
Abstract: We studied superconducting gap dynamics in a BCS superconductor NbN and electron doped cuprate superconductor PCCO following excitation with near-infrared (NIR) and narrow band THz pulses. Systematic studies on PCCO imply very selective electron-phonon coupling.
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Korneev, A. A., Korneeva, Y. P., Mikhailov, M. Y., Pershin, Y. P., Semenov, A. V., Vodolazov, D. Y., et al. (2015). Characterization of MoSi superconducting single-photon detectors in the magnetic field. IEEE Trans. Appl. Supercond., 25(3), 2200504 (1 to 4).
Abstract: We investigate the response mechanism of nanowire superconducting single-photon detectors (SSPDs) made of amorphous MoxSi1-x. We study the dependence of photon count and dark count rates on bias current in magnetic fields up to 113 mT at 1.7 K temperature. The observed behavior of photon counts is similar to the one recently observed in NbN SSPDs. Our results show that the detecting mechanism of relatively high-energy photons does not involve the vortex penetration from the edges of the film, and on the contrary, the detecting mechanism of low-energy photons probably involves the vortex penetration from the film edges.
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Ozhegov, R. V., Gorshkov, K. N., Vachtomin, Y. B., Smirnov, K. V., Finkel, M. I., Goltsman, G. N., et al. (2014). Terahertz imaging system based on superconducting heterodyne integrated receiver. In C. Corsi, & F. Sizov (Eds.), Proc. THz and Security Applications (pp. 113–125). Dordrecht: Springer Netherlands.
Abstract: The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compared to traditional systems.
In this project we propose a prototype THz imaging system using an 1 pixel SIR and 2D scanner. At a local oscillator frequency of 500 GHz the best noise equivalent temperature difference (NETD) of the SIR is 10 mK at an integration time of 1 s and a detection bandwidth of 4 GHz. The scanner consists of two rotating flat mirrors placed in front of the antenna consisting of a spherical primary reflector and an aspherical secondary reflector. The diameter of the primary reflector is 0.3 m. The operating frequency of the imaging system is 600 GHz, the frame rate is 0.1 FPS, the scanning area is 0.5 × 0.5 m2, the image resolution is 50 × 50 pixels, the distance from an object to the scanner was 3 m. We have obtained THz images with a spatial resolution of 8 mm and a NETD of less than 2 K.
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Zhang, W., Miao, W., Zhong, J. Q., Shi, S. C., Hayton, D. J., Vercruyssen, N., et al. (2014). Temperature dependence of the receiver noise temperature and IF bandwidth of superconducting hot electron bolometer mixers. Supercond. Sci. Technol., 27(8), 085013 (1 to 5).
Abstract: In this paper we study the temperature dependence of the receiver noise temperature and IF noise bandwidth of superconducting hot electron bolometer (HEB) mixers. Three superconducting NbN HEB devices of different transition temperatures (Tc) are measured at 0.85 THz and 1.4 THz at different bath temperatures (Tbath) between 4 K and 9 K. Measurement results demonstrate that the receiver noise temperature of superconducting NbN HEB devices is nearly constant for Tbath/Tc, less than 0.8, which is consistent with the simulation based on a distributed hot-spot model. In addition, the IF noise bandwidth appears independent of Tbath/Tc, indicating the dominance of phonon cooling in the investigated HEB devices.
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