  We predict a gigantically long lifetime of the first excited state of an
interstitial lithium donor in silicon. The nature of this effect roots in the
anomalous level structure of the {\em 1s} Li manifold under external stress.
Namely, the coupling between the lowest two states of the opposite parity is
very weak and occurs via intervalley phonon transitions only. We propose to use
these states under the controlled ac and dc stress to process quantum
information. We find an unusual form of the elastic-dipole interaction between
%the electronic transitions in different donors. This interaction scales with
the inter-donor distance $R$ as $R^{-3}$ or $R^{-5}$ for the transitions
between the states of the same or opposite parity, respectively. The long-range
$R^{-3}$ interaction provides a high fidelity mechanism for 2-qubit operations.

Quantum Physics;Other Condensed Matter