Trainable Associative Memory Neural Networks in a Quantum-Dot Cellular Automata

Quantum-dot cellular automata (QCAs) offer a diffusive computing paradigm with picosecond transmission speed, making them an ideal candidate for moving diffusive computing to real-world applications. By implementing a trainable associative memory neural network into this substrate, we demonstrate that high-speed, high-density associative memory is feasible through QCAs. The presented design occupies $415\text{nm}^2$ per neuron, which translates to circa $240 \text{ billion neurons/cm}^2$, or $28\text{GB/cm}^2$ of memory storage, offering a real possibility for large-scale associative memory circuits. Results are presented from simulation, demonstrating correct working behaviour of the associative memory in single neurons, two-neuron and four-neuron arrays.