Quantum criticality and dynamical instability in the kicked-top model

Phys Rev Lett. 2014 Apr 11;112(14):140408. doi: 10.1103/PhysRevLett.112.140408. Epub 2014 Apr 11.

Abstract

We investigate precursors of critical behavior in the quasienergy spectrum due to the dynamical instability in the kicked top. Using a semiclassical approach, we analytically obtain a logarithmic divergence in the density of states, which is analogous to a continuous excited state quantum phase transition in undriven systems. We propose a protocol to observe the cusp behavior of the magnetization close to the critical quasienergy.