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Thermal noise in superconducting quantum point contacts

1996; American Physical Society; Volume: 53; Issue: 14 Linguagem: Inglês

10.1103/physrevb.53.r8891

1095-3795

A. Martín‐Rodero, A. Levy Yeyati, F. J. García‐Vidal,

Semiconductor Quantum Structures and Devices

We present a theory for the frequency-dependent current fluctuations in superconducting quantum point contacts (SQPC) within the dc transport regime. This theory is valid for any barrier transparency between the tunnel and ballistic limits, yielding an analytical expression for the fluctuations spectrum in the subgap region. It is shown that the level of noise in a quasiballistic SQPC may have a huge increase in comparison with the case of a normal contact carrying the same average current. The effect of this high level of noise on the actual observability of the current-phase relation for a ballistic point contact is discussed in connection with recent experimental measurements.