Noise-mediated cooperative behavior in a system of coupled DC SQUIDs

We study the oscillator equations describing a system of coupled DC-SQUIDs. The circulating current in each SQUID is inductively and globally coupled to the loop currents in the other SQUIDs. Just beyond the onset of spontaneous oscillations, the system shows significantly enhanced sensitivity to very weak magnetic fields. The ability to quantify the oscillation frequency permits its exploitation as a detection/analysis tool in remote sensing applications. Here we present quantitative results about such oscillation frequency and its scaling in terms of the control parameters, and the number of SQUIDs involved. For infinitely many coupled SQUIDs, at the thermodynamic limit, we derive a nonlinear Fokker-Planck equation. This mean-field equation allows us to explore the various regimes of operation of the system analytically as well as numerically.