A Search for Stimulated Emission of Radiation From Superconducting Tunnel Junctions

1973 ◽  
Vol 51 (4) ◽  
pp. 465-476 ◽  
Author(s):  
A. A. Fife ◽  
S. Gygax
Keyword(s):  
Energy Gap ◽  
Tunnel Junctions ◽  
Narrow Band ◽  
Frequency Converter ◽  
Broad Band ◽  
Radiation Detectors ◽  
Exhaustive Search ◽  
Stimulated Emission ◽  
Superconducting Tunnel Junctions ◽  
Radiative Emission

A report is made of an exhaustive search for stimulated emission of energy gap radiation from superconducting tunnel junctions of the form Ta–oxide–A1. Two types of radiation detectors have been employed—bolometers for broad band detection and a superconducting frequency converter tunable in the range of interest for narrow band work. The present search has been completely unsuccessful and this negative result has spurred a reexamination of both the theory and the experiments. Serious doubts are raised as to the validity of earlier claims and it is concluded that the previous probable observation of radiative emission requires a different interpretation.

Effects of Quasiparticle Diffusion in Nb-Based Superconducting Tunnel Junctions Under X-Rays Irradiation

1999 ◽  
Vol 13 (09n10) ◽  
pp. 1247-1252
Author(s):  
Emanuela Esposito ◽  
Luigi Frunzio ◽  
Loredana Parlato ◽  
Roberto Cristiano ◽  
Mikhall Lisitskii ◽  
...  
Keyword(s):  
Tunnel Junctions ◽  
Signal Amplitude ◽  
Radiation Detectors ◽  
Superconducting Tunnel Junctions ◽  
X Rays ◽  
Theoretical Limit ◽  
X Ray ◽  
Operational Temperature ◽  
Amplitude Spectra ◽  
Quasiparticle Diffusion

A novel class of sensors is constituted by radiation detectors based on superconducting tunnel junctions, which could lead in the next future to an advanced instrumentation with an interesting fall out for applications. So far, this area is restricted to LTc superconductors. Among them, niobium has the highest critical temperature and is therefore less demanding in terms of operational temperature. The best performances achieved so far in pure Nb-based junction are far away from the expected theoretical limit. The reason of this discrepancy could be attributed to various problems. Quasiparticle diffusion and edge losses seem to be responsible for the broadening of the signal amplitude spectra so often observed and reported in literature. In this paper we report on efforts to investigate the response to X-Ray of Nb-based superconducting tunnel junctions in terms of a model which includes the quasiparticle diffusion and the edge losses. Our model takes into account the contribution from both the electrodes of the junction and well reproduces the experimental data.

Lateral proximity effect and long-range energy-gap gradients in Ta/Al and Nb/Al superconducting tunnel junctions

2001 ◽  
Vol 63 (21) ◽  
Author(s):  
Roland den Hartog ◽  
A. Golubov ◽  
P. Verhoeve ◽  
A. Poelaert ◽  
D. Martin ◽  
...  
Keyword(s):  
Long Range ◽  
Proximity Effect ◽  
Energy Gap ◽  
Tunnel Junctions ◽  
Superconducting Tunnel Junctions

SOME PHONON EFFECTS IN SUPERCONDUCTING TUNNEL JUNCTIONS

1965 ◽  
Vol 43 (4) ◽  
pp. 557-562 ◽  
Author(s):  
J. G. Adler ◽  
J. S. Rogers ◽  
S. B. Woods
Keyword(s):  
Temperature Dependence ◽  
Phonon Spectrum ◽  
Energy Gap ◽  
Tunnel Junctions ◽  
Phonon Energy ◽  
Superconducting Tunnel Junctions ◽  
Tunnel Current ◽  
Broad Group ◽  
Superconducting Energy Gap ◽  
Phonon Structure

Tunneling measurements have been made on junctions consisting of aluminium separated from a second metal by aluminium oxide insulating layers. When the second metal was lead, tin, or indium, the effect of its phonon spectrum on the tunnel current was observed. Results with indium indicate that there is a broad group of phonons at an energy of 5 millivolts and another group at an energy of 13 millivolts in the indium phonon spectrum. The end point of the spectrum is at 14.8 ± 0.1 millivolts. Evidence is presented for a relationship between the strength of the phonon structure, the phonon energy, and the width of the superconducting energy gap from measurements on lead, tin, and indium. Measurements of the temperature dependence of the phonon structure in lead and indium are also reported.

Observation of stimulated radiative emission from normal to superconducting metal junctions

1969 ◽  
Vol 47 (11) ◽  
pp. 1171-1176 ◽  
Author(s):  
W. D. Gregory ◽  
L. Leopold ◽  
D. Repici
Keyword(s):  
Current Density ◽  
Free Space ◽  
Energy Gap ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Stimulated Emission ◽  
Point Contacts ◽  
Radiative Emission ◽  
Superconducting Metal

Approximately 10−7 W of radiation at the energy-gap frequency of Ta (3 mm wavelength at 4.26 °K) has been observed traveling through free space from specially formed Ta–Al point contacts. This radiation appears discontinuously at a threshold current density of about 105 A/cm2, disappears as the sample is warmed above Tc, and appears to be tunable by changing the energy gap with temperature. These results are consistent with our predictions of stimulated emission from normal–superconductor contacts.

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