Sound wave amplification in superconductors

✍ Scribed by P. Otschik; H. Eschrig; F. Lange

• Book ID: 104626685
• Publisher: Springer US
• Year: 1981
• Tongue: English
• Weight: 436 KB
• Volume: 43
• Category: Article
• ISSN: 0022-2291
• DOI: 10.1007/bf00116164

✦ Synopsis

The possibility of generating an occupation inversion n(E) > 89 in a nonequilibrium superconducting state by tunnel injection is discussed. By investigating the combined densities of states of the processes involved, a condition on the occupation function n(E) for sound wave amplification is derived, which generally is more restrictive than occupation inversion. It is shown that occupation inversion can be generated only in nonsymmetric superconductorinsulator-superconductor tunnel ]unctions where the superconducting layers are of different thicknesses. The thickness of the amplifying layer must not exceed the diffusion length of the quasiparticles. The estimates suggest that sound wave amplification should in principle be possible.