  We show how nanostructuring of a metallic gate on a field-effect transistor
(FET) can lead to a macroscopic, robust and voltage controlled quantum state in
the electron channel of a FET. A chain of triple quantum dot molecules created
by gate structure realizes a spin-half Heisenberg chain with spin-spin
interactions alternating between ferromagnetic and anti-ferromagnetic. The
quantum state is a semiconductor implementation of an integer spin-one
antiferromagnetic Heisenberg chain with a unique correlated ground state and a
finite energy gap, originally conjectured by Haldane.
