Quantum-dot cellular automata (QCA) technology is considered to be a possible alternative for circuit implementation in terms of energy efficiency, integration density and switching frequency. Multiplexer (MUX) can be considered to be a suitable candidate for designing QCA circuits. In this paper, two different structures of energy-efficient $2\times 1$ MUX designs are proposed. These MUXes outperform the best existing design in terms of power consumption with approximate reductions of 26% and 35%. Moreover, similar or better performance factors such as area and latency are achieved compared to the available designs. These MUX structures can be used as fundamental energy-efficient building blocks for replacing the majority-based structures in QCA. The scalability property of the proposed MUXes is excellent and can be used for energy-efficient complex QCA circuit designs.

Cellular arrays have been the topic of interest in computer arithmetic and architecture for the last four decades. In this letter, an overall quantum-dot cellular automata (QCA) design for a generalized pipeline cellular array is presented. QCA is one of the promising emerging nanotechnologies that are being considered as possible alternatives to complementary metal-oxide semiconductor technology due to the physical limitations of CMOS. The QCA designs for arithmetic cell and control cell used in the pipeline array are discussed in detail. The equivalent majority logic networks to these cells are generated using the best existing majority logic synthesis method in order to obtain the optimal majority networks which require fewer QCA cells and clock zones compared to other synthesis methods. The proposed array can perform all the basic arithmetic operations such as squaring, square rooting, multiplication, division, etc., which could be quite valuable in considering future large-scale QCA designs.

In this study, we propose a quantum structure of an associative memory cell for effective data learning based on artificial intelligence. For effective learning of related data, content-based retrieval and storage rather than memory address is essential. A content-addressable memory (CAM), which is an efficient memory cell structure for this purpose, in a quantum computing environment, is designed based on quantum-dot cellular automata (QCA). A CAM cell is composed of a memory unit that stores information, a match unit that performs a search, and a structure, using an XOR gate or an XNOR gate in the match unit, that shows good performance. In this study, we designed an XNOR gate with a multilayer structure based on electron interactions and proposed a QCA-based CAM cell using it. The area and time efficiency are verified through a simulation using QCADesigner, and the quantum cost of the proposed XOR gate and CAM cell were reduced by at least 70% and 15%, respectively, when compared to the latest research. In addition, we physically proved the potential energy owing to the interaction between the electrons inside the QCA cell. We also proposed an additional CAM circuit targeting the reduction in energy dissipation that overcomes the best available designs. The simulation and calculation of power dissipation are performed by QCADesigner-E and it is confirmed that more than 27% is reduced.

Recently a great deal of interest has been shown by researchers on developing a bio-molecule based computer. The basic building blocks of such a computer are arithmetic units and memory. These units can be designed using Boolean logic gates as in the case of electronic circuits. Instead of using silicon based technology, Boolean logic gates can be generated from biological systems. One such system can be generated by a DNA reaction mechanism based on a reversible strand displacement process. A generalized pipeline architecture employing DNA reaction chain mechanism for the arithmetic operations such as addition, subtraction, multiplication, and division is discussed in this paper. A single control line is used in the pipeline array to control the different modes of operations. The primary functional blocks in a pipelined array are arithmetic unit and control unit. These units are made up of basic Boolean logic gates. To implement these gates, a DNA strand displacement process is employed. A set of integrating and amplifying gates are used in cascade with different threshold values to build different digital logic operations. The main advantage of such a system is that the arithmetic operations can be overlapped in the pipeline and thus a high speed operation is possible. Such a general Boolean model will be a step towards the development of a bio-computer. The ultimate goal of such a method is to design an automated system using logic gates, which make decisions within living cells.

The applications of digital circuits are well known in all walks of life. In this paper the procedure for the development of Nano digital circuits is given. The procedure requires the Boolean function realization for the application in mind. The proposed technique works for any Boolean Function. The Boolean functions are written in the form of Exclusive OR, AND and NOT gates. The functions are then written as ONLY majority gates. The Majority gates are implemented using QCA (Quantum Cellular Automata Logic). QCA are one of the established approaches for nanotechnology. An algorithm is established by which a universal procedure can be established for implementing Boolean Functions using Nano logic. These functions are written in Verilog language. The Verilog program can be tested on FPGA's. Cadence software can be used to design a chip. The research in Nano Medicine has attracted the attention of scientists recently. The applications of Nano digital circuits in Molecular medicine are discussed. It is hoped that this procedure will result in a large number of applications of Nano logic and open a way to the development and use of Nano digital circuits in molecular medicine.

One of the nanoscale technologies that shows its capability of implementing integrated digital circuits with low power, high speed, and high density is quantum-dot cellular automata (QCA). The fundamental device for designing and implementing circuits in QCA is majority logic. In this paper, a novel energy-efficient QCA design of three-input AND/OR logic functions is proposed. This design can perform both AND and OR logic operations using the same structure with an achievement of 58% and 64% approximate reductions in power consumption compared to majority-based structures, and 31% and 32% approximate reductions in power consumption compared to the best available circuits, respectively. In addition, other physical constraints such as area and latency are improved and have better or similar results compared to the best existing circuits. The proposed circuit can be considered as a fundamental and better alternative to the majority gate for energy-efficient circuit design in QCA. This will pave the way for developing efficient large-scale QCA-based sequential and combinational circuits.