DYNAMICS OF SUPERFLUID QUANTUM ATOMIC GASES AND ATOMIC NUCLEI WITHIN THE FRAMEWORK OF DENSITY FUNCTIONAL THEORY

摘要

Time-dependent density functional theory can be viewed as an exact reformulation of time-dependent quantum mechanical problem, where the fundamental variable is no longer the many-body wave-function but the density. For systems like atomic nuclei and quantum atomic gases this approach has to be extended in order to deal with superfluid fermionic systems. We have introduced a local extension of the time-dependent density functional theory to describe the dynamics of fermionic superfluids. Such calculations require however extensive computational resources, as one has to solve tens to hundreds of thousands, or more,of nonlinear coupled PDEs. Therefore we have created extremely accurate, fast and efficient software which enable to investigate the real-time evolution of up to 30000 superfluid fermions on the 3D lattice without any symmetry restrictions. I will illustrate the power of this approach by studying the generation of quantized vortices, vortex rings, vortex reconnection, and transition from a superfluid to a normal state in real time for a unitary Fermi gas. We predict the emergence of a new qualitative phenomenon in superfluid dynamics of gases, the existence of stable superfluidity when the systems are stirred with velocities significantly exceeding the nominal Landau critical velocity in these systems. Moreover I will present generation of shock waves and domain walls in collisions of clouds of thousands of atoms as well as preliminary investigations of nuclear dynamics.