The quantumdot cellular automata qca approach offers an attractive alternative in which binary information is encoded in the configuration of charge. Pdf fabrication and measurement of molecular quantum cellular. In the static treatment, the difference between stationary states before and after. These groups of qds are named quantum dot molecules. Pdf quantumdot cellular automata at a molecular scale. We show how to construct a simple model hamiltonian. Quantumchemical design of molecular quantumdot cellular.
Qca is transistorless computational paradigm which can achieve device density. However, it still remains a challenge to find appropriate. Coulomb interactions provide devicedevice coupling without current flow. A new molecular implementation in quantum cellular automata. A molecular qca implementation promises ultrahigh device densities, high switching speeds, and. The development of theoretical quantummechanical models. Cellular automata are commonly implemented as software programs. However, it still remains a challenge to find appropriate candidate molecules for mqca operation.
Electricfield inputs for molecular quantumdot cellular automata circuits. Performance analysis on quantumdot cellular automata. Eliminating wire crossings for molecular quantumdot. Design of arithmetic processor in molecular quantumdot. Fieldeffect transistor fetbased microelectronics is approaching its size limit due to unacceptable power dissipation and shortchannel effects. Quasiclassical modeling of molecular quantumdot cellular. The quantumdot cellular automata qca approach offers an attractive alternative in which binary information is encoded in the configuration of charge among redoxactive molecular sites. Molecular quantumdot cellular automata qca paradigm is a promising approach to molecular electronics. Quantumdot cellular automata qca is a lowpower, nonvon neumann, general purpose paradigm for classical computing using.
Quantumdot cellular automata qca is an approach to computing which eliminates the need for transistors by representing binary digits as charge configurations rather than current levels. Molecular quantumdot cellular automata enrique pacis blair united states naval academy dated. Power dissipation in clocking wires for clocked molecular. A 3d universal structure based on molecularqca and cnt technologies. Molecular quantumdot cellular automata journal of the.
In the molecular quantumdot cellular automata qca paradigm clocking wires are used to produce an electric field which is perpendicular to the device plane of surfacebound molecules and is sinusoidally modulated in space and time. Molecular qca uses redox sites of molecules as quantum dots. We establish a method for exploring the dynamics of molecular quantumdot cellular automata qca devices by hierarchically combining the techniques of quantum chemistry with the nonequilibrium timedependent coherence vector formalism. Discussed here are the basic paradigm of qca, materials systems in which qca might be constructed, a series of. The automaton quickly gained popularity and it was first fabricated in 1997. When exploring computing elements made from technologies other than cmos, it is imperative to investigate the effects of physical implementation constraints. Nano express open access quasiclassical modeling of. Qca is transistorless computational paradigm which. Molecular quantumdot cellular automata request pdf. The device under study was composed of four metal dots, connected with tunnel junctions and capacitors, and operated at localization. Nano express open access quasiclassical modeling of molecular quantumdot cellular automata multidriver gates ehsan rahimi and shahram mohammad nejad abstract molecular quantumdot cellular automata mqca has received considerable attention in nanoscience.
Recently reported quantumdot cellular automata qca exclusiveor gate designs are usually made with the andorinverter method in which it is difficult to optimize the xor gate. Represent information with molecular charge configuration. Single qca molecules are characterized using ab initio quantum chemistry methods. Molecular quantumdot cellular automata is the most promising and challenging technology nowadays for its high operating frequency, extremely high device density and noncryogenic working temperature. Quantumdot cellular automata qca is a lowpower, nonvonneumann, general purpose paradigm for classical computing using. Our studies support the experimental interpretation that this molecule has a bistable electronic state, and that binary information can be encoded in the molecular. Then molecular cells can be arranged in order to design logical gates whose. Binary multipliers on quantumdot cellular automata 543 our pipelined array multiplier. Quantumdot cellular automata qca is a paradigm for lowpower, highspeed, highly dense computing that could be realized in a variety of materials systems.
Quantumdot cellular automata qca is a scheme for molecular electronics in which information is transmitted and processed through electrostatic interactions between charges in an array of quantum dots. A second fundamental expectation relies on their molecular nature, a feature that paves the way to fabrication. In the qca paradigm information is represented in the charge configuration of a qca cell, which maps naturally to a binary model. Realization of a functional cell for quantumdot cellular. The quantumdot cellular automata qca approach offers an attractive alternative in which binary information is encoded in the configuration of. This paper focuses on molecular quantumdot cellular automata circuits. A theoretical study on the implementation of quantum dot cellular automata. Electricfield inputs for molecular quantumdot cellular automata. Quantumdot cellular automata revolutionary, not incremental, approach beyond transistors requires rethinking circuits and architectures use molecules, not as current switches, but as structured charge containers. We present an ab initio quantum chemistry study of. A new molecular implementation in quantum cellular. The quantumdot cellular automata qca approach offers an attractive alternative in.
Unlike the currentbased molecular switches, where the digital data is represented by the onoff states of the switches, in mqca devices, binary information is encoded in. Read counterionfree molecular quantumdot cellular automata using mixed valence zwitterions a doubledot derivative of the closo 1cb 9 h 10. These functional molecules were specifically designed for molecular quantumdot cellular automata, a computational paradigm where charge configurations are used to represent binary states. All experiments were carried out in ultrahigh vacuum and at lowtemperature 77 k. For these circuits, it is very difficult for chemists to fabricate wire crossings at least in the near future. Theoretical study of molecular quantumdot cellular automata. Among these evolving nanotechnologies, quantumdot cellular automata is the most favorable technology 1. From molecular structure to circuit dynamics yuhui lu, mo liu, and craig lenta department of electrical engineering, university of notre dame, notre dame, indiana 46565 received 23 february 2007. Design of arithmetic processor in molecular quantumdot cellular automata abstract nano digital circuits have been the topic of interest in molecular medicine for the last three decades. Our interest in mixedvalence complexes is as a potential molecular implementation of quantumdot cellular automata qca,,,, a promising approach to molecular electronics.
Devices are typically analyzed with quantum physicsbased approaches which are far from the electronic engineering world and make it difficult to design, simulate and fabricate. Mj frisch, gw trucks, hb schlegel, ge scuseria, ma robb, jr cheeseman, vg zakrzewski. Molecular quantumdot cellular automata and the relevance of robinday classification, chemical physics letters on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Current lines of investigation include choosing candidate molecules, 7, 21, clocking on the molecular scale 10, and circuit selfassembly 4. Department of electrical engineering, university of notre dame.
Qca cells can be implemented using mixedvalence compounds. Quantumdot cellular automata qca may provide a novel way to bypass the transistor paradigm to form ultrasmall computing elements. However, the existence of counterions can perturb the local electric field and thus is detrimental to. The interaction of the quantum mechanics with the coulomb in every cell, is the one that determines the cell state. Molecular qca implementations are being explored where the quantum dots in the cell take the form of redox centers in a molecule. Clock topologies for molecular quantumdot cellular automata. This clocking field guides the data flow through the molecular qca array. Quantumdot cellular automata qca is a transistorless computation. Localization and cellcell response in tetrameric mixedvalence units andrew palii institute of applied physics, academy of sciences of moldova, kishinev, moldova. Quantum dot molecules for quantum cellular automata. A tetrairon dication featuring tetraethynylbenzene.
Pdf an introduction to the operation of quantumdot cellular automata is presented, along with recent experimental results. Clocking of molecular quantumdot cellular automata. The main idea of quantum dot cellular automata 116 is demonstrated in fig. Power is dissipated in clocking wires due to the nonzero resistance of the conductors. Automatic cell placement for quantumdot cellular automata. Molecular electronics and quantumdot cellular automata most approaches to molecular electronics have sought to reproduce conventional electronic elements, such as transistors, wires, or diodes. This electronic framework therefore provides the possibility of an all. Quantumchemical design of molecular quantumdot cellular automata qca. Signal transmission through molecular quantumdot cellular.
This illustrates the robustness of information encoding in the qca scheme. Some researchers have analyzed some human body operations as equivalent to simple nano gates and their connections. Molecular quantum dot cellular automata mqca is a promising transistorless paradigm that encodes binary information with bistable charge configurations instead of currents and voltages. Effectiveness of molecules for quantum cellular automata. Pdf an overview is given of the qca architecture, along with a summary of.
As a replacement for cmos technology, quantum cellular automata was proposed by lent et al. Counterionfree molecular quantumdot cellular automata. Notwithstanding the increasing interest in molecular quantumdot cellular automata mqca as emerging devices for computation, a characterization of their behavior from an electronic standpoint is not wellstated. Pdf theoretical study of molecular quantum dot cellular. Clocking of molecular quantumdot cellular automata university of. Molecular electronics is commonly conceived as reproducing diode or transistor action at the molecular level. Quantumdot cellular automata qca 5 and resonant tunneling diodes rtd 6 are some of the beyond cmos technologies. The quantum cellular automaton qca concept represents an attempt to break away from the traditional threeterminal device paradigm that has dominated digital computation.
The quantum dot molecules consist of 1012 dots surrounding each. In order to distinguish this proposal from models of cellular automata. Molecular quantum dot cellular automata based on diboryl. Abstract quantumdot cellular automata qca is a novel. Since its early formulation in 1993 at notre dame university, the qca idea has received significant attention and several physical implementations have been proposed. The key idea in qca is to encode binary information as the charge configuration of a cell. Design and analysis of a novel lowpower exclusiveor gate. Like the previous work by braunsand and wiest 18, dinuclear metal complexes shown in fig.
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