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CAMP Seminar: Fast preparation of critical ground states using superluminal fronts.

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Kartiek Agarwal, Princeton University
When
07 November 2017 from 3:30 PM to 4:30 PM
Where
339 Davey Laboratory
Contact Name
Jainendra Jain
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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 superluminally-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. The physics of the dynamical problem can be understood in terms of relativistic rarefaction of excitations generated by the mass front. 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 discuss the role of interactions and UV effects on the free-theory idealization, before numerically illustrating the usefulness of the approach via simulations on the quantum Heisenberg spin-chain. 

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