A Signal Distribution Network for Sequential Quantum-dot Cellular Automata Systems

The authors describe a signal distribution network for sequential systems constructed using the Quantum-dot Cellular Automata (QCA) computing paradigm. This network promises to enable the construction of arbitrarily complex QCA sequential systems in which all wire crossings are performed using nearest neighbor interactions, which will improve the thermal behavior of QCA systems as well as their resistance to stray charge and fabrication imperfections. The new sequential signal distribution network is demonstrated by the complete design and simulation of a two-bit counter, a three-bit counter, and a pattern detection circuit

Matrix multiplication using quantum-dot cellular automata to implement conventional microelectronics

Quantum-dot cellular automata (QCA) shows promise as a post silicon CMOS, low power computational technology. Nevertheless, to generalize QCA for next-generation digital devices, the ability to implement conventional programmable circuits based on NOR, AND, and OR gates is necessary. To this end, we devise a new QCA structure, the QCA matrix multiplier (MM), employing the standard Coulomb blocked, five quantum dot (QD) QCA cell and quasi-adiabatic switching for sequential data latching in the QCA cells. Our structure can multiply two N x M matrices, using one input and one bidirectional input/output data line. The calculation is highly parallelizable, and it is possible to achieve reduced calculation time in exchange for increasing numbers of parallel matrix multiplier units. We show convergent, ab initio simulation results using the Intercellular Hartree Approximation for one, three, and nine matrix multiplier units. The structure can generally implement any programmable logic array (PLA) or any matrix multiplication based operation.Comment: 14 pages, 9 figures, supplemental informatio

Quantum Cellular Neural Networks

We have previously proposed a way of using coupled quantum dots to construct digital computing elements - quantum-dot cellular automata (QCA). Here we consider a different approach to using coupled quantum-dot cells in an architecture which, rather that reproducing Boolean logic, uses a physical near-neighbor connectivity to construct an analog Cellular Neural Network (CNN).Comment: 7 pages including 3 figure

A Signal Distribution Grid for Quantum-dot Cellular Automata

Coplanar wire crossing has been a major challenge for quantum-dot cellular automata systems since their development. Several possible solutions have been presented, but they have either relied on non-adjacent cell interactions or have required switching time that scales with the number of inputs or outputs. In this paper, the authors present a signal distribution grid that enables multiple parallel crossings, while doing so with only adjacent cell interactions, a constant time for signal distribution regardless of the number of inputs or outputs, and regularly shaped and contiguous clocking regions that will be relatively easier to fabricate. The utility of this device is demonstrated by the design of a one-bit full adder that meets all of the listed requirements

Programmable Logic Implemented Using Quantum-Dot Cellular Automata

The authors describe a geometric layout of quantum-dot cellular automata (QCA) cells and an associated set of clock signals that can be used to implement a programmable array of logic (PAL). PALs are an important category of programmable logic that can be programmed (typically once) to perform a particular sum-of-products Boolean operation. The particular device described has six inputs, four product terms, and one output. The connections between the inputs and the product terms are fully re-programmable, while the connections between the product terms and the output are hardwired. This device takes 22 clock cycles to load the connection data and then completes the calculation in 57 cycles. The connection data are preserved in memory, so additional calculations with the same set of connections can be performed in just 57 cycles each

A signal calculation grid for quantum-dot cellular automata

The quantum-dot cellular automata (QCA) computing paradigm presents great promise as a potential strategy for future nanocomputing devices. Perhaps the greatest challenge facing the QCA architecture is finding a robust wire crossing strategy. In this paper, the recently introduced QCA signal distribution grid is extended to carry out generalized sum-of-products and product-of-sums calculations that are performed concurrently with signal distribution. The new signal calculation grid is capable of performing an arbitrary number of simultaneous programmable Boolean operations on an arbitrary number of inputs, and the time required to perform all of these parallel calculations is just seven clock cycles