A macroscopic 'order parameter' for many-body localization

Event Dates: 

Friday, March 20, 2015 - 10:30am

CTQM Seminar Type: 

  • CTQM Discussion

Seminar Location: 

  • Duane Physics Room G1B20

Speaker Name(s): 

Mark Fischer

Speaker Affiliation(s): 

Weizmann Institute

Abstract, Event Details: 

Recent theoretical progress in characterizing many-body localized systems has not been confronted so far with an experimental test. I will present a theoretical analysis of new experimental results showing many-body localization of  interacting fermions in a quasi periodic optical lattice potential (arXiv:1501.05661). Specifically we considered the time evolution of a system prepared in a particular many-body initial state, a charge-density wave. Relaxation of the density-wave to a non-vanishing value at long times provides a direct demonstration of the breakdown of ergodicity in the many-body localized state and the saturation value can serve as an order parameter of this state. We found this stationary density wave order to show a distinctive dependence on the interaction strength, in agreement with experiment. Moreover, I will discuss how (temporal) fluctuations in this order parameter are connected to the entanglement-entropy growth, thus providing a distinguishing signature that could be observed in future experiments.