Minimizing irreversible losses in quantum systems by local counter-diabatic driving

TL;DR

This paper introduces a variational method to design local counter-diabatic protocols that minimize irreversible losses in quantum systems, enabling faster and more efficient quantum annealing in complex many-particle systems.

Contribution

A simple variational approach to find approximate local counter-diabatic protocols that reduce dissipation and improve fidelity in large, complex quantum systems.

Findings

Protocols drastically decrease dissipation in quantum annealing.

Fidelity of quantum processes is significantly increased.

Protocols are easy to implement experimentally and numerically.

Abstract

Counter-diabatic driving protocols were proposed as a means to do fast changes in the Hamiltonian without exciting transitions. Such driving in principle allows one to realize arbitrarily fast annealing protocols or implement fast dissipationless driving, circumventing standard adiabatic limitations requiring infinitesimally slow rates. These ideas were tested and used both experimentally and theoretically in small systems, but in larger chaotic systems it is known that exact counter-diabatic protocols do not exist. In this work we develop a simple variational approach allowing one to find best possible counter-diabatic protocols given physical constraints like locality. These protocols are easy to derive and implement both experimentally and numerically. We show that, using these approximate protocols, one can drastically decrease dissipation and increase fidelity of quantum annealing protocols in complex many-particle systems. In the fast limit these protocols provide an effective dual description of adiabatic dynamics where the coupling constant plays the role of time and the counter-diabatic term plays the role of the Hamiltonian.