  We study quantum entanglement loss due to environmental interaction in a
condensed matter system with a complex geometry relevant to recent proposals
for computing with single electrons at the nanoscale. We consider a system
consisting of two qubits, each realized by an electron in a double quantum dot,
which are initially in an entangled Bell state. The qubits are widely separated
and each interacts with its own environment. The environment for each is
modeled by surrounding double quantum dots placed at random positions with
random orientations. We calculate the unitary evolution of the joint system and
environment. The global state remains pure throughout. We examine the time
dependence of the expectation value of the bipartite Clauser-Horne-Shimony-Holt
(CHSH) and Brukner-Paunkovi\'c-Rudolph-Vedral (BPRV) Bell operators and explore
the emergence of correlations consistent with local realism. Though the details
of this transition depend on the specific environmental geometry, we show how
the results can be mapped on to a universal behavior with appropriate scaling.
We determine the relevant disentanglement times based on realistic physical
parameters for molecular double-dots.
