Detection of ultrafast oscillations in Superconducting Point-Contacts by   means of Supercurrent Measurements
  We present a microscopic calculation of the nondissipative current through a superconducting quantum point contact coupled to a mechanical oscillator. Using the non-equilibrium Keldysh Green function approach, we determine the current-phase relation. The latter shows that at certain phases, the current is sharply suppressed. These dips in the current-phase relation provide information about the oscillating frequency and coupling strength of the mechanical oscillator. We also present an effective two-level model from which we obtain analytical expressions describing the position and width of the dips. Our findings are of relevance for nanomechanical resonators based on superconducting materials. 
R. Avriller, F. S. Bergeret and F. Pistolesi
cond-mat.mes-hall