  Out of thermal equilibrium, bosonic quantum systems can Bose-condense away
from the ground state, featuring a macroscopic occupation of an excited state
or even of multiple states in the so-called Bose-selection scenario. In
previous work, a theory was developed that predicts, in which states a
driven-dissipative ideal Bose gas condenses. Here, we address the inverse
problem: Given a target state with desired condensate fractions in certain
single-particle states, how can this configuration be achieved by tuning
available control parameters? Which type of experimental setup allows for
flexible condensation control? We solve these problems, on the one hand, by
proposing a Bose `condenser', experimentally implementable in a superconducting
circuit, where targeted Bose condensation into eigenstates of a chain of
resonators is driven through the coupling to artificial quantum baths, realized
via auxiliary two-level systems. On the other, we develop a theory to solve the
inverse problem based on linear programming methods. We further discuss the
engineering of transition points between different Bose condensation
configurations, which may find application for amplification, heat-flow
control, and the design of highly-structured quantum baths.
