9 research outputs found
Melting a Hubbard dimer: benchmarks of 'ALDA' for quantum thermodynamics
The competition between evolution time, interaction strength, and temperature
challenges our understanding of many-body quantum systems out-of-equilibrium.
Here we consider a benchmark system, the Hubbard dimer, which allows us to
explore all the relevant regimes and calculate exactly the related average
quantum work. At difference with previous studies, we focus on the effect of
increasing temperature, and show how this can turn competition between
many-body interactions and driving field into synergy. We then turn to use
recently proposed protocols inspired by density functional theory to explore if
these effects could be reproduced by using simple approximations. We find that,
up to and including intermediate temperatures, a method which borrows from
ground-state adiabatic local density approximation improves dramatically the
estimate for the average quantum work, including, in the adiabatic regime, when
correlations are strong. However at high temperature and at least when based on
the pseudo-LDA, this method fails to capture the counterintuitive qualitative
dependence of the quantum work with interaction strength, albeit getting the
quantitative estimates relatively close to the exact results