"Diabatic approach to creating ground states of certain critical models"

Speaker: Kartiek Agrawal, Princeton University

When: October 6, 2017 (Fri), 12:00PM to 01:30PM (add to my calendar)
Location: SCI 352
Hosted by: Anatoli Polkovnikov

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

We propose a spatio-temporal quench protocol that allows for the fast preparation of ground states of gapless models with Lorentz invariance. Assuming the system initially resides in the ground state of a corresponding massive model, we show that a supersonically-moving ‘front’ that locally quenches the mass, leaves behind it (in space) a state arbitrarily close to the ground state of the gapless model. Importantly, our protocol takes time O (L) to produce the ground state of a system of size ∼ Ld (d spatial dimensions), while a fully adiabatic protocol requires time ∼ O( L2) to produce a state with exponential accuracy in L. We provide proof-of-concept by solving the proposed quench exactly for a system of free bosons in arbitrary dimensions, and for free fermions in d = 1. We also discuss the role of interactions and UV effects on the free-theory idealization, before numerically illustrating the usefulness of the approach using simulations on classical phonons and on the quantum Heisenberg spin-chain with a mass induced by local magnetic fields.