The kicked top — a periodically driven quantum spin system — shows precursors of critical behavior in its quasienergy spectrum that stem from dynamical instability rather than a conventional equilibrium phase transition. Using a semiclassical approach, this paper derives a logarithmic divergence in the density of states, analogous to a continuous excited-state quantum phase transition in undriven systems, and proposes a protocol to observe the resulting cusp behavior in the magnetization.
Read the paper
- Authors: Victor Manuel Bastidas, Pedro Pérez-Fernández, Malte Vogl, and Tobias Brandes
- Journal: Physical Review Letters 112, 140408 (2014)
- DOI: 10.1103/physrevlett.112.140408