Counterflow Quantum Turbulence and the Instability in Two-component Bose-Einstein Condensates

We theoretically study the nonlinear dynamics of the instability of counter-superflow in two miscible Bose-Einstein condensates. The condensates become unstable when the relative velocity exceeds a critical value, which is called counter-superflow instability. We reveal that the counter-superflow instability can lead to quantum turbulence by numerically solving the coupled Gross-Pitaevskii equations. The modes amplified by the instability grow into solitons and decay into quantized vortices.Eventually, the vortices become tangled and quantum turbulence of two superfluids. We show that this process may occur in experiments by investigating the dynamics in a 2D trapped system.