  All known superfluid and superconducting states of condensed matter are
enabled by composite bosons (atoms, molecules, Cooper pairs) made of an even
number of fermions. Temperatures where such macroscopic quantum phenomena occur
are limited by the lesser of the binding energy and the degeneracy temperature
of the bosons. High critical temperature cuprate superconductors set the
present record of ~100 K. Here we propose a design for artificially structured
materials to rival this record. The main elements of the structure are two
monolayers of a transition metal dichalcogenide separated by an atomically thin
spacer. Electrons and holes generated in the system would accumulate in the
opposite monolayers and form bosonic bound states --- the indirect excitons.
The resultant degenerate Bose gas of indirect excitons would exhibit
macroscopic occupation of a quantum state and vanishing viscosity at high
temperatures.
