A Gross-Pitaevskii theory for an excitonic incompressible Bose solid

Abstract: We show that interlayer excitons in double-layer semiconductor heterostructures can form a Bose solid, which is an incompressible supersolid characterized by exactly one boson per lattice site. This exciton Bose solid would be the first realization of an incompressible supersolid, unlike the generally compressible cluster supersolids seen in dipolar quantum gases. Capturing its characteristics and associated emergent phenomena requires extending the Gross-Pitaevskii formalism to include strong two-particle correlations and exclude exciton self-interactions. We develop such a formalism, we apply it across experimentally accessible exciton densities and interlayer separations, and we show that it incorporates both superfluid and incompressible supersolid ground states. This extended framework allows us to determine the superfluid-supersolid transition and explore the low-temperature properties of the exciton supersolid across its complete parameter space.