Classical verification of a quantum simulator: local relaxation of a 1D Bose gas

In [Nat. Phys. 8, 325-330 (2012)], Trotzky et al. utilize ultracold atoms in an optical lattice to simulate the local relaxation dynamics of a strongly interacting Bose gas "for longer times than present classical algorithms can keep track of". Here, I classically verify the results of this analog quantum simulator by calculating the evolution of the same quasi-local observables up to the time at which they appear "fully relaxed". Using a parallel implementation of the time-evolving block decimation (TEBD) algorithm to simulate the system on a supercomputer, I show that local densities and currents can be calculated in a matter of days rather than weeks. The precision of these numerics allows me to observe deviations from the conjectured power-law decay and to determine the effects of the harmonic trapping potential. As well as providing a robust benchmark for future experimental, theoretical, and numerical methods, this work serves as an example of the independent verification process.