“…While general qualitative insights can help to understand some quandaries arising from Maxwell's demon or Szilard's engine [8][9][10], and correlations play various interesting roles in quantum thermodynamics (see, e.g., [2,3,[11][12][13][14][15][16][17][18]), precise quantitative statements about the trade-off between work and correlations are generally complicated. For example, by allowing arbitrarily slow quasi-static operations and perfect control over arbitrarily many auxiliary systems, one may provide tight lower bounds on the work cost of creating bipartite correlations as measured by the mutual information [7,11,12,19,20]. However, for two identical systems, these bounds are tight only in the case when specific so-called symmetrically thermalizing unitaries (STUs) exist, i.e., unitaries that map initial thermal states to locally thermal states at higher local effective temperatures.…”