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Quantum cellular AutomataQuantum cellular Automata

• Quantum Cellular Automata (QCA) refers to any one of several models of quantum computation, which have been devised in analogy to conventional models of cellular automata introduced by von Neumann. It may also refer to quantum dot cellular automata, which is a proposed physical implementation of "classical" cellular automata by exploiting quantum mechanical phenomena.

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Quantum cellular AutomataQuantum cellular Automata

• 4 quantum SED dot• 2 electrons added to system• System will minimize electro-static energy

01

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Quantum cellular Automata :ExampleQuantum cellular Automata :Example

• Input1

Propagate a 1

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Quantum cellular Automata: LogicQuantum cellular Automata: Logic

• Based on neighbor interaction– Vs movement of charge

• Key advantages– Very low power

• Key disadvantage– No gain.– Input not isolated from output

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5Quantum cellular Automata : Logic Gate Quantum cellular Automata : Logic Gate exampleexample

• Input A

0

Propagate a 0

• Input C

• Input B

0

0

1

Voting gate

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An InverterAn Inverter6

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HistoryHistory

• Proposed in 1993 by Lent et. al. • Based on ground state computation• System moves to lowest electro-static energy

state• State of lowest energy uniquely defined• Key issue is energy level between states and kT.• 1997 physical implementation of QCA produced

– Tunnnel junctions and Al islands– Experiment at 10mK

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S. E. Thompson EEL 6935

Ferroelectric RAMFerroelectric RAM9

DRAM