Finite size effects in global quantum quenches: examples from free bosons in an harmonic trap and the one-dimensional Bose-Hubbard model

Understand

We investigate finite size effects in quantum quenches on the basis of simple energetic arguments.

• Distinguishing between the low-energy part of the excitation spectrum, below a microscopic energy-scale, and the high-energy regime enables one to define a crossover number of particles that is shown to diverge in the small quench limit.
• Another crossover number is proposed based on the fidelity between the initial and final ground-states.
• Both criteria can be computed using ground-state techniques that work for larger system sizes than full spectrum diagonalization.