We formulate a new paradigm for computing with cellular automata (CAS) composed of arrays of quantum devices-quantum cellular automata. Computing in such a paradigm is edge driven. Input, output, and power are delivered at the edge of the cnarray only; no direct flow of information or energy to internal cells is required. Computing in this paradigm is also computing with the ground state. The architecture is so designed that the ground-state configuration of the array, subject to boundary conditions determined by the input, yields the computational result. We propose a specific realization of these ideas using two-electron cells composed of quantum dots, which is within the reach of current fabrication technology. The charge density in the cell is very highly polarized (aligned) along one of the two cell axes, suggestive of a twostate CA. The polarization of one cell induces a polarization in a neighboring cell through the Coulomb interaction i n a very non-linear fashion. Quantum cellular automata can perform useful computing. We show that AND gates, OR gates, and inverters can be constructed and interconnected.

We examine the possible implementation of logic devices using coupled quantum dot cells. Each quantum cell contains two electrons which interact Coulombically with neighboring cells. The charge distribution in each cell tends to align along one of two perpendicular axes, which allows the encoding of binary information using the state of the cell. The state of each cell is affected in a very nonlinear way by the states of its neighbors. A line of these cells can be used to transmit binary information. We use these cells to design inverters, programmable logic gates, dedicated AND and OR gates, and non-interfering wire crossings. Complex arrays are simulated which implement the exclusive-OR function and a single-bit full adder.

We describe a paradigm for computing with interacting quantum dots, quantum-dot cellular automata (QCA). We show how arrays of quantum-dot cells could be used to perform useful computations. A new adiabatic switching paradigm is developed which permits clocked control, eliminates metastability problems, and enables a pipelined architecture.

A simple model quantum dot cell containing two electrons is analyzed as a candidate for quantum cellular automata implementations. The cell has eigenstates whose charge density is strongly aligned along one of two directions. In the presence of the electrostatic perturbation due to a neighboring cell, the ground state is nearly completely aligned (polarized) in one direction only. The polarization is a highly nonlinear function of the perturbing electrostatic fields and shows the strong bistable saturation important for cellular automation function.

The behavior of linear arrays of cells composed of quantum dots is examined. Each cell holds two electrons and interacts Coulombically with neighboring cells. The electrons in the cell tend to align along one of two axes resulting in a cell "polarization" which can be used to encode binary information. The ground-state polarization of a cell is a highly nonlinear function of the polarization of its neighbors. The resulting bistable saturation can be used to transmit binary information along the line of cells, thus forming a binary wire. 6227