The Free On-line Dictionary of Computing (30 December 2018):

quantum cell

    (Or "quantum dot cell") A structure
   comprising four quantum dots arranged in a square, with two
   diagonally opposed dots containing electron charges.  One
   diagonal containing charges is arbitrarily defined as
   representing a value of '1', the other as '0'.  In a five-dot
   cell, the fifth, central dot contains no charge.

   See also: quantum cell wire, quantum-dot cellular
   automata.

   (http://mitre.org/research/nanotech/quantum_dot_cell.html).

   ["Quantum Dot Heterostructures", D. Bimberg, et al, John Wiley
   & Sons Ltd., Dec 1998].

   [Implementations?]

   (2001-07-17)