quantum dot cellular automata - ucsb

Quantum‐Dot Cellular Automata

M i fMain reference:

QCA ‐main ideaQCA  main idea

QCA devicesQCA devices

QCA full adderQCA full adder

One of the challenges: Kink energyOne of the challenges: Kink energy

Kink energy should be >> KbTshould be   KbT

QCA implementation

Metal‐dot QCA cells and devicesMetal dot QCA cells and devices

Metal‐dot QCA cells and devicesMetal dot QCA cells and devices

Clocked QCA cells (Lent design)Clocked QCA cells (Lent design)

Clocked QCA cells (Likharev design)Clocked QCA cells (Likharev design)

K. K. Likharev and A. N. Korotkov, Science 273. (1996) 763‐765

Three‐dot QCA latch operationThree dot QCA latch operation

QCA shift register

QCA shift registerQCA shift register

Adiabatic clocking in QCAAdiabatic clocking in QCA

Two schemes (similar to CMOS l k )clocking)

Molecular QCAMolecular QCA

Molecular QCA clockingMolecular QCA clocking

Magnetic QCAMagnetic QCA

QCA problems ‐ 1QCA problems  1

• Wire crossingsWire crossings 

• Communication is computation

i f ? Superior performance?

QCA problems ‐ 2

• Critical dimension variations or low T (could be solve with large redundancy)be solve with large redundancy)

Superior performance?