Measurements of the Maximum Josephson Supercurrent vs. Magnetic Field as a Probe of Tunnel Barrier Uniformity
Nonequilibrium quasiparticle distributions can be studied as a result of elastic single-particle electron tunneling in superconducting junctions. The use of a tunnel junction both for creation and detection of nonequilibrium states is widely reported in the literature. Quasiparticle, phonon and photon generation by tunneling have been in fact investigated, as well as phonon, and microwave detection, etc. For instance, a simple symmetric (i.e., equal superconducting gaps Δ1=Δ2=Δ) junction can be used in the voltage region V<2Δ/e for the detection of phonons of energy V1ω>2Δ (see Chapter 3). Another example is a structure consisting of two superimposed tunnel junctions with one superconducting layer in common (i.e., a S-I-S-I-S structure), which has been successfully employed in a variety of experiments of nonequilibrium superconductivity (see Chapter 5). In this case the role of the one junction is the creation of the nonequilibrium superconducting state, whereas the second serves as a probe of such a state. The possibility of phonon detection by using Josephson junctions has also been demonstrated (e.g., Tredwell and Jacobsen, 1974).
KeywordsJosephson Junction Tunnel Junction Background Current Magnetic Field Dependence Current Density Distribution
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