Voltage locking and other interactions in coupled superconducting weak links. II. Experiment

Experiments have been performed on two superconducting indium microbridges fabricated in close proximity ({} 2 {μ}m) to one another. The observed interactions include the following: (i) the apparent critical current of one bridge depends upon the current and voltage across the other bridge; (ii) gross modifications of the current-voltage characteristics of one bridge occur which are dependent on the current and voltage across the neighboring bridge; and (iii) strong voltage pulling is observed whenever the two bridge voltages are approximately equal, resulting in dc-voltage locking under appropriate conditions. The "voltage-locking" interaction is of particular interest, and data are presented showing its observed temperature and frequency dependence. It is shown that the observed interactions are in qualitative agreement with a model based upon the diffusion of quasiparticles generated during the phase-slip process.