Quantum adiabatic cycles and their breakdown

Abstract

An analytically solvable model for quasi-static transformations across quantum critical points featuring Bosonic quasi-particle excitations is presented. The model proves that adiabaticity breakdown is a general feature of universal slow dynamics in these systems. The existence of an "anti-adiabatic" dynamical phase with vanishing ground state fidelity in the slow drive limit is also proven. The relation of these findings with the Kibble-Zurek mechanism and their consequences on defect formation in many body systems ramped across a quantum phase transition are discussed.

Harnessing non-adiabatic excitations promoted by a quantum critical point

“…As a consequence of the breakdown of the adiabatic condition due to a vanishing energy gap (g c ) = 0 [29], the initial state is never retrieved upon a slow cycle, regardless of how slow it is performed, that is, independently of how large ωτ is [72,76]. In particular, the resulting final state after one cycle for ωτ 1 acquires a squeezing [72]…”