English

Ramp and periodic dynamics across non-Ising critical points

Strongly Correlated Electrons 2018-01-29 v2

Abstract

We study ramp and periodic dynamics of ultracold bosons in an one-dimensional (1D) optical lattice which supports quantum critical points separating a uniform and a Z3Z_3 or Z4Z_4 symmetry broken density-wave ground state. Our protocol involves both linear and periodic drives which takes the system from the uniform state to the quantum critical point (for linear drive protocol) or to the ordered state and back (for periodic drive protocols) via controlled variation of a parameter of the system Hamiltonian. We provide exact numerical computation, for finite-size boson chains with L24L \le 24 using exact-diagonalization (ED), of the excitation density DD, the wavefunction overlap FF, and the excess energy QQ at the end of the drive protocol. For the linear ramp protocol, we identify the range of ramp speeds for which DD and QQ shows Kibble-Zurek scaling. We find, based on numerical analysis with L24L \le 24, that such scaling is consistent with that expected from critical exponents of the qq-state Potts universality class with q=3,4q=3,4. For periodic protocol, we show that the model display near-perfect dynamical freezing at specific frequencies; at these frequencies D,Q0D, Q \to 0 and F1|F| \to 1. We provide a semi-analytic explanation of such freezing behavior and relate this phenomenon to a many-body version of Stuckelberg interference. We suggest experiments which can test our theory.

Keywords

Cite

@article{arxiv.1710.07646,
  title  = {Ramp and periodic dynamics across non-Ising critical points},
  author = {Roopayan Ghosh and Arnab Sen and K. Sengupta},
  journal= {arXiv preprint arXiv:1710.07646},
  year   = {2018}
}

Comments

v2,final version accepeted in PRB