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Author Varyukhin, S. V.; Zakharov, A. A.; Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Chulkova, G. M.
Title (up) Low energy excitation in La2CuO4 Type Journal Article
Year 1990 Publication Sverkhprovodimost': Fizika, Khimiya, Tekhnika Abbreviated Journal Sverkhprovodimost': Fizika, Khimiya, Tekhnika
Volume 3 Issue 5 Pages 832-837
Keywords metal-dielectric-La2CuO4, monocrystals
Abstract Measurements of transmission and photoconductivity spectra in submillimeter wave length range as well as of capacity C and conductivity G in the region of acoustic frequencies of metal-dielectric-La2CuO4 system at low temperatures are performed using La2CuO4 monocrystals. Optical spectra posses a threshold character, a sharp decrease of transmission and photocoductivity signal occurs in the energy region hν>1.5 MeV. C(ω,T) and G(ω, T) dependences have a universal form typical of Debye type relaxation processes. Relaxation time dependence is of thermoactivated character τ(T)∼exp(ξ/T) with the gap value ξ≅2 meV. It is assumed that excitations with characteristic energy of ∼2 meV exist in La2CuO4. A possible nature of the detected low-energy excitations is discussed.
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Call Number Serial 1688
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Author Karpov, A.; Miller, D.; Rice, F.; Zmuidzinas, J.; Stern, J. A.; Bumble, B.; LeDuc, H. G.
Title (up) Low noise 1.2 THz SIS receiver Type Conference Article
Year 2001 Publication Proc. 12th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 21-22
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Publisher Place of Publication San Diego, CA, USA Editor Jet Propulsion Laboratory, California Inst.it.u.t.e of Technology
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Call Number RPLAB @ s @ sis_650K_at_1p13THz Serial 316
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Author Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Maslennikova, Anna; Kaurova, Natalia; Lobastova, Anastasia; Voronov, Boris; Gol'tsman, Gregory
Title (up) Low noise and wide bandwidth of NbN hot-electron bolometer mixers Type Journal Article
Year 2011 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 98 Issue Pages 033507 (1 to 3)
Keywords NbN HEB mixer
Abstract We report a record double sideband noise temperature of 600 K (5hν/kB) offered by a NbN hot-electron bolometer receiver at 2.5 THz. Allowing for standing wave effects, this value was found to be constant in the intermediate frequency range 1–7 GHz, which indicates that the mixer has an unprecedentedly large noise bandwidth in excess of 7 GHz. The insight into this is provided by gain bandwidth measurements performed at the superconducting transition. They show that the dependence of the bandwidth on the mixer length follows the model for an HEB mixer with diffusion and phonon cooling of the hot electrons.
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Call Number RPLAB @ gujma @ Serial 638
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Author Khosropanah, P.; Gao, J. R.; Laauwen, W. M.; Hajenius, M; Klapwijk, T. M.
Title (up) Low noise NbN hot electron bolometer mixer at 4.3 THz Type Journal Article
Year 2007 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 91 Issue Pages 221111 (1 to 3)
Keywords NbN HEB mixers, NbN, contacts cleaning
Abstract We have studied the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a spiral antenna at 4.3 THz. Using hot/cold blackbody loads and a beam splitter all in vacuum, we measured a double sideband receiver noise temperature of 1300 K at the optimum local oscillator (LO) power of 330 nW, which is about 12 times the quantum noise (hnu/2kB). Our result indicates that there is no sign of degradation of the mixing process at the superterahertz frequencies. Moreover, a measurement method is introduced which allows us for an accurate determination of the sensitivity despite LO power fluctuations.
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Call Number Serial 584
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Author Kawamura, J.; Blundell, R.; Tong, C.-yu E.; Gol’tsman, G.; Gershenzon, E.; Voronov, B.; Cherednichenko, S.
Title (up) Low noise NbN lattice-cooled superconducting hot-electron bolometric mixers at submillimeter wavelengths Type Journal Article
Year 1997 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 70 Issue 12 Pages 1619-1621
Keywords NbN HEB mixers
Abstract Lattice-cooled superconducting hot-electron bolometric mixers are used in a submillimeter-wave waveguide heterodyne receiver. The mixer elements are niobium nitride film with 3.5 nm thickness and ∼10 μm2 area. The local oscillator power for optimal performance is estimated to be 0.5 μW, and the instantaneous bandwidth is 2.2 GHz. At an intermediate frequency centered at 1.4 GHz with 200 MHz bandwidth, the double sideband receiver noise temperature is 410 K at 430 GHz. The receiver has been used to detect molecular line emission in a laboratory gas cell.
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number Serial 1599
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