Physics (Internal)

How to probe many-body localized phase?

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: Recently it was demonstrated that the many-body localized phase can be characterized by the existence of infinitely many local conservation laws. These local integrals of motion can be viewed as effective quantum spins that have conserved z-components. This picture shows that the dynamics of the many-body localized phase is limited to dephasing between distant effective spins. Slow logarithmic entanglement growth for initial product states is one signature of the restricted dynamics of the many-body localized phase. However, the entanglement entropy is difficult to observe experimentally.

In this talk, after reviewing the description of the MBL phase in terms of conserved quantities [1], we explore experimentally observable consequences of dynamics in the MBL phase. We argue that a characteristic slow power-law decay of local observables is a signature of the MBL phase that is measurable experimentally. In particular, we propose a specific protocol to probe the dephasing of a given spin due to its entanglement with a set of distant spins [2]. The proposed response function exhibits a power-law decay that is robust with respect to thermal and disorder averaging. We also briefly discuss the quench dynamics and spectral functions of local operators. We will discuss numerical simulations supporting our results.

[1] M. Serbyn, Z. Papic, D. A. Abanin, Phys. Rev. Lett. 111, 127201 (2013). [2] M. Serbyn et. al., arXiv:1403.0693.