AQC 2016 - Driving Spin Systems with Noisy Control Fields: Limits to Adiabatic Protocol

A Google TechTalk, June 27, 2016, presented by Adolfo del Campo (University of Massachusetts) ABSTRACT: We consider driving a thermally isolated system across a quantum phase transition by a noisy control field. At variance with the defect suppression under slow noise-free driving predicted by the Kibble-Zurek mechanism, we show that in the presence of external noise in the control, the system may exhibit an anti-Kibble-Zurek behavior, where slower driving results in a higher density of excitations at the end of the process. For the transverse field Ising model, we show that the noise-averaged dynamics is effectively described by a purely dephasing Lindbladian. Exploiting this connection, we find the density of defects as a function of the quench rate and the noise strength and determine the optimal driving time for defect suppression, which scales as universal power of the noise amplitude. Our findings show the limitation of adiabatic protocols imposed by noise in the control fields and motivates the use of shortcuts to adiabaticity as an alternative. Armin Rahmani, University Of British Columbia, Anirban Dutta, University of Massachusetts Presented at the Adiabatic Quantum Computing Conference, June 26-29, 2016, at Google's Los Angeles office.