Quantum Lattice-Gas Algorithm for Quantum Turbulence - CAP Simulations on 12,288 Cores of Cray XT-5 Einstein at NAVO

Abstract

A novel unitary quantum lattice algorithm is developed to explore quantum turbulence. Because of its low memory requirements and its near perfect parallelization to the full 12,288 cores on the Cray XT5, simulations were run up to spatial grids of 5,7603. The Gross-Pitaevskii equation, which describes the ground state of a Bose Einstein condensate (BEC), is solved and it is found that the incompressible kinetic energy spectrum exhibits 3 distinct power laws: classical Kolmogorov k?5/3 spectrum at scales much larger than the individual quantum vortex cores, and a quantum Kelvin wave cascade spectrum of k?3 at scales of the order of the quantum cores. In the adjoining semiclassical regime, there is a steeper spectral decay transitioning between the classical and quantum regimes. However, its spectral exponent does not seem to be universal. This is the first, first-principle simulation yielding the universal quantum Kelvin cascade exponent.