Cooling through optimal control of quantum evolution

TL;DR

This paper demonstrates that optimal control via bang-bang protocols can enhance cooling in coupled quantum gases by nonadiabatic evolution, with potential broad applications.

Contribution

It introduces a bang-bang optimal control protocol for quantum evolution that achieves effective cooling beyond current methods.

Findings

Optimal bang-bang control maximizes desired figures of merit.

Nonadiabatic protocols can cool quasicondensates beyond existing techniques.

Potential for broad application through experimental and computational integration.

Abstract

Nonadiabatic unitary evolution with tailored time-dependent Hamiltonians can prepare systems of cold atomic gases with various desired properties. For a system of two one-dimensional quasicondensates coupled with a time-varying tunneling amplitude, we show that the optimal protocol, for maximizing any figure of merit in a given time, is bang-bang, i.e., the coupling alternates between only two values through a sequence of sudden quenches. Minimizing the energy of one of the quasicondensates with such nonadiabatic protocols, and then decoupling it at the end of the process, can result in effective cooling beyond the current state of the art. Our cooling method can be potentially applied to arbitrary systems through an integration of the experiment with simulated annealing computations.