Quantumdot cellular automata represent binary information by charge configuration of cell. Molecular quantumdot cellular automata based on diboryl. Research in the fields of physics, chemistry and electronics has demonstrated that quantumdot cellular automata qca is a viable alternative for nanoscale computing. Before discussing quantum dot cellular automata, it is worth discussing quantum dots and the confinement of electrons in the dots. Ripple clock schemes for quantumdot cellular automata. Universal shift register implementation using quantum dot.
The majority gate voter and inverter are the basic logic gates in the qca architecture designing. The first design leverages the complement addition method, while the second design uses the direct subtraction method. These quantum dots are sites in which electrons are able to tunnel between them but cannot leave the cell. Computation and information transfer in qca is based on.
Abstractquantum dot cellular automata qca are an emerging nanotechnology with remarkable performance and energy ef. The use of buried dopants to construct quantum dot cellular automata is investigated as an alternative to conventional electronic devices for information. In this regard, quantumdot cellular automata qca lent and tougaw 1997 are a promising candidate. Fieldeffect transistor fetbased microelectronics is approaching its size limit due to unacceptable power dissipation and shortchannel effects. Qca uses quantum mechanical effects in the device at the molecular scale. Memory architecture for quantumdot cellular automata. Accordingly, the design of reversible qca circuits is an active field of research. This technique is based on the interaction of electrons. Quantumdot cellular automata serial decimal subtractors. Since the first introduction of quantum dot cellular automata qca, an interesting nanoscale computing paradigm by lent et al. They employ a fieldcoupled nanotechnology fcn in which information is stored in terms of the polarity of small cells and can be propagated to adjacent.
The four dots are located at the corners of the cell and only two electrons are injected into a cell. Design of 1bit comparator using 2 dot 1 electron quantum. An improved eigensolver for quantumdot cellular automata. A line of three two dot cells is presented, which demonstrates that there are no metastable states in a qca line. In recent years, a group of researchers have presented a generalization of the basic qca cell, namely the ternary qca tqca cell 710, which. In this paper we present a novel design for qca cells and another possible and unconventional scheme for majority gates. The basic boolean primitive in qca is the majority gate. Performance evaluation of efficient xor structures in. Design and implementation of new feynman and toffoli nft. Design rules for quantumdot cellular automata request pdf. Each cell has four quantum dots which can hold a single electron per dot. In this paper we introduce qca logic gates such has qca inverter and qca majority gate. Quantumdot cellular automata qca is a lowpower, nonvonneumann, generalpurpose paradigm for classical.
Abstractquantumdot cellular automata qca are an emerging nanotechnology with remarkable performance and energy efficiency. Demonstration of a sixdot quantum cellular automata system. Cmos scaling is currently facing a technological barrier. Quantum dot cellular automata qca is a novel nanotechnology with great potential for very dense memory and low power logic. Quantum dot cellular automata is a mean of representing binary information on cells, through which no current flows, and achieving device performance by the coupling of those cells 5,7. A layout of four and eight bit universal shift register usr has been proposed.
Design of sequential circuit using quantum dot cellular. Two dimensional 2 dot 1 electron qca is the structural variation of qca. A novel design for quantumdot cellular automata cells and. The noise coupling problem is solved by arranging the qca cells and assigning the clocking zones. The building block of quantum dot cellular automata are cells and quantum dots or holes.
Evaluating the impact of interconnections in quantumdot cellular. Quantum dot cellular automata in detailed explained. Quantum cellular automata, heuristic algorithms, quantum dots, quantum computing i. Implementation of multiclb designs using quantumdot. This law put forth by moore has been a benchmark for semiconductor scaling. However, it still remains a challenge to find appropriate. Cellular automata may be seen as an extreme form of simple. Qca is an abstract quantum computational nanotechnology based on fieldcoupled arrays of finitestate automata. Quantum dot cellular automata qca demands to be a promising alternative of cmos in ultra large scale circuit integration.
To be considered as a suitable cmos candidate, qca must be. They employ a fieldcoupled nanotechnology fcn in which information is stored in terms of the polarity of small cells and can be propagated to adjacent cells using electrostatic force coulomb interaction. Abstractquantum dot cellular automata qca is an emerging nanotechnology, with the potential for faster speed, smaller size, and lower power consumption than transistorbased technology. Quantum dot cellular automata, clock zone, majority gate, multiplexer, and parallel memory. Mqca offers very low power dissipation together with high integration density of functional devices, as qca implementations do in general.
Logic scl gates in quantum dot cellular automata qca. Quantum dot cellular automata qca is one of the alternative technology. The work in this paper describes the application of an optimized eigensolver algorithm to produce the kernel. Each of the xor gate 3, 4, has an inordinate latency and very complex circuit. Abstract the use of quantum dots is a promising emerging technology for implementing digital systems at the nanoscale level. In this regard, quantum dot cellular automata qca lent and tougaw 1997 are a promising candidate.
Quantum automata pdf university of nijmegen, the netherlands. Quantum dot cellular autometa presents a promissing nanoscale technology for replacement of conventional cmos based circuits. A quantum dot cellular automata qca is a square nanostructure of electron wells confining free electrons. In contrast, novel nanotechnologies like quantum dot cellular automata qca allow for computations with very low energy dissipation and hence are promising candidates for breaking this limit. It is considered as an alternative to widely used complementary metal oxide semiconductor cmos technology because of its key features, which include low power operation, high density and high operating frequency. It is a digital logic architecture that uses single electrons in arrays of quantum dots. Quantum dot cellular automata visit physics tomorrow webpage references. As the name clearly suggests that a 2 dot 1electron qca cell consists of. Evaluating the impact of interconnections in quantumdot. Arithmetic and logic unit designs using qca are of high research interest. The following definition of cellular automaton appears in cellular. Experimental studies of quantum dot cellular automata devices. We provide an introduction to quantum cellular automata. Unlike conventional logic circuits in which information is transferred by.
Quantum dot cellular automata qca is an emerging technology for building digital circuits at nanoscale. Focus on the graphical user interface, which enables the user to construct, simulate and analyze structures. Electricfield inputs for molecular quantumdot cellular automata circuits. Two designs for quantum dot cellular automata serial decimal subtractors are proposed for a nanocomputer. Novel design of nbit controllable inverter by quantumdot.
Qca systems have the potential for low power, high density, and regularity. Implementation of 4x4 vedic multiplier using carry save. Physical systems proposed for qca include quantum dot arrays and endohedral. Quantum dot cellular automata has a simple cell as the basic element.
Logic levels in qca are represented by the configurations of single electrons in arrays of coupled quantumdots. Novel technologies are being proposed to keep up with the need for computation power and speed. Implementation of one bit parallel memory cell using. Quantum dot, single electron devices, quantum dot cellular automata, coulomb blockade, logic gate 7227 1. Quantumdot cellular automata qca is a potential nanoelectronic technology for information processing. Near zeroenergy computation using quantumdot cellular. Were not really talking about realworld time here, but about the ca living over a period of time, which could also be called a generation and, in our. Quantum dot cellular automata qca the fundamental unit of qca device is qca cell. Optimized design and performance analysis of novel comparator and full adder in nanoscale. Quantum dot cellular automaton qca is an emerging, promising, future generation nanoelectronic computational architecture that encodes binary information as electronic charge configuration of a. International journal of science and engineering, 91, 912. As a consequence, new strategies are required for design automation approaches in order to cope with the arising. Discussed here are the basic paradigm of qca, materials systems in which qca might be constructed, a series of experiments performed in the metal tunnel.
Molecular quantum dot cellular automata mqca is a promising transistorless paradigm that encodes binary information with bistable charge configurations instead of currents and voltages. Different formations of cells lead to different variants of qca. A near zeroenergy computation using quantumdot cellular. We havent yet discussed, however, what is perhaps the most important detail of how cellular automata worktime.
One of the proposed ideas is the quantum dot cellular automata qca technology. Sandeep inakollu,1 xiaobo pan,3 jing ma,4 haibo yu1,2 1school of chemistry, university of wollongong, nsw 2522, australia 2illawarra health and medical research institute, wollongong, nsw 2522, australia 3college of chemistry and chemical engineering, lanzhou. A design tool for ternary quantumdot cellular automata core. To be considered as a suitable cmos candidate, qca must be able to implement complex real. The external field reduces the potential barrier between the twostable statesand erases the pre. An improved eigensolver for quantum dot cellular automata simulations a. Introduction quantumdot cellular automata qca is a computational nanotechnology that employs a 2d patterned array of charge or magnetically coupled. For your thesis study the existing tools for simulating ternary quantum dot cellular automata and design software equipment for visual designing of such systems. Automatic cell placement for quantumdot cellular automata. Today, standard solid state qca cell design considers the distance between quantum dots to be about 20 nm, and a distance between cells of about 60 nm. Just like any ca, quantum dot cellular automata are based on the simple interaction rules between cells placed on a grid. This paper is a study of cellular automata as computational programs. Quantum dot cellular automaton qca is an emerging, promising, future generation nanoelectronic computational architecture that encodes binary information as electronic charge configuration of a cell. Quantumdot cellular automata qca is one of the most important computing technologies for the future and will be.
This work presents the hmemory architecture, a memory architecture that exploits the characteristics of qca and results in order of magnitude density gains over end of the roadmap sram and dram. Taylor baldwin, jeffrey will, douglas tougaw electrical and computer engineering valparaiso university valparaiso, indiana aaron. Qca uses geometrically arranged arrays of quantum wells quantum dot cells to encode and process binary information. The 5bit johnsonmobius code is used to encode decimal digits. Introduction according to gordon moore1965, the number of transistors that can be integrated on to a single chip will double every 18 months. Abstractquantum dot cellular automata qca is a novel and potentially attractive technology for implementing computing architectures at the nanoscale. In this paper a new architecture for quantum dot cellular. Abstract quantum dot cellular automata qca offers a novel alternative to the transistor paradigm. Matching architecture to qca device characteristics is of high importance and failure to do so may squander potential gains. By the clocking mechanism, the electrons can tunnel through to. A qca cell, created with four quantum dots positioned at the vertices of a square 16 17, coupled by tunneling barriers has been in figure 1a. In qca the cell is used for logic computation and also used for interconnection i. Conventional device physics is based on a free electron model which treats carriers in a material as if they were free electrons with a reduced effective mass which reflects the properties of the material.
Realization of efficient quantum dot cellular automata based. Algorithms for embedding quantumdot cellular automata. Molecular quantum dot cellular automata based on diboryl. The proposed subtractors are compared to the existing quantum dot cellular automata decimal adders. Electricfield inputs for molecular quantumdot cellular automata. S1 molecular quantum dot cellular automata based on diboryl monoradical anions xingyong wang,1,2 lirong yu,3 v. Optimum multiplexer design in quantumdot cellular automata. Quantum dot cellular automata are a proposed improvement on conventional computer design cmos, which have been devised in analogy to conventional. The same name may also refer to quantum dot cellular automata, which are a proposed physical implementation of classical cellular automata by exploiting quantum mechanical phenomena. Each qca device cell consists of a bistable or tristable semiconductor molecular structure of quantum dots.