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. December 20, 2009 abstract quantumdot cellular automata qca is a novel, currentfree approach to computing at the nanoscale, which, if realized in computing devices, will have broadreaching e ects in the electronics industry. A molecular qca implementation promises ultrahigh device densities, high switching speeds, and. Performance analysis on quantumdot cellular automata. The development of theoretical quantummechanical models. These groups of qds are named quantum dot molecules. Represent information with molecular charge configuration. Theoretical study of 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.
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. Among these evolving nanotechnologies, quantumdot cellular automata is the most favorable technology 1. Fieldeffect transistor fetbased microelectronics is approaching its size limit due to unacceptable power dissipation and shortchannel effects. Mj frisch, gw trucks, hb schlegel, ge scuseria, ma robb, jr cheeseman, vg zakrzewski. Design of arithmetic processor in molecular quantumdot. We show how to construct a simple model hamiltonian. Read counterionfree molecular quantumdot cellular automata using mixed valence zwitterions a doubledot derivative of the closo 1cb 9 h 10.
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. The quantumdot cellular automata qca approach offers an attractive alternative in. Molecular quantumdot cellular automata journal of the. Pdf fabrication and measurement of molecular quantum cellular. Quasiclassical modeling of molecular quantumdot cellular. Power dissipation in clocking wires for clocked molecular. 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 device under study was composed of four metal dots, connected with tunnel junctions and capacitors, and operated at localization.
Qca is transistorless computational paradigm which can achieve device density. A theoretical study on the implementation of quantum dot cellular automata. The automaton quickly gained popularity and it was first fabricated in 1997. This paper presents an experimental demonstration of a basic cell of the quantumdot cellular automata, a transistorless approach to computation that addresses the issues of device density, interconnection, and power dissipation.
Qca cells can be implemented using mixedvalence compounds. Then molecular cells can be arranged in order to design logical gates whose. In the static treatment, the difference between stationary states before and after. However, it still remains a challenge to find appropriate. Molecular electronics is commonly conceived as reproducing diode or transistor action at the molecular level. Department of electrical engineering, university of notre dame. Future quantum computer 33 increasing the thickness of inas regrown layer to 1.
The quantumdot cellular automata qca approach offers an attractive alternative in which binary information is encoded in the configuration of charge. Nano express open access quasiclassical modeling of. Coulomb interactions provide devicedevice coupling without current flow. Abstract quantumdot cellular automata qca is a novel. When exploring computing elements made from technologies other than cmos, it is imperative to investigate the effects of physical implementation constraints.
Pdf quantumdot cellular automata at a molecular scale. Effectiveness of molecules for quantum cellular automata. The quantumdot cellular automata qca approach offers an attractive alternative in which binary information is encoded in the configuration of. Molecular quantumdot cellular automata enrique pacis blair united states naval academy dated. 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.
The key idea in qca is to encode binary information as the charge configuration of a cell. Cellular automata are commonly implemented as software programs. For these circuits, it is very difficult for chemists to fabricate wire crossings at least in the near future. Molecular qca uses redox sites of molecules as quantum dots. Molecular qca implementations are being explored where the quantum dots in the cell take the form of redox centers in a molecule. In the qca paradigm information is represented in the charge configuration of a qca cell, which maps naturally to a binary model. Quantumdot cellular automata qca 5 and resonant tunneling diodes rtd 6 are some of the beyond cmos technologies. Molecular quantum dot cellular automata based on diboryl.
Electricfield inputs for molecular quantumdot cellular automata circuits. Quantumchemical design of molecular quantumdot cellular. A new molecular implementation in quantum cellular automata. A second fundamental expectation relies on their molecular nature, a feature that paves the way to fabrication. 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. These functional molecules were specifically designed for molecular quantumdot cellular automata, a computational paradigm where charge configurations are used to represent binary states. Like the previous work by braunsand and wiest 18, dinuclear metal complexes shown in fig. Clocking of molecular quantumdot cellular automata university of. Molecular quantumdot cellular automata request pdf.
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. 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. 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. Clocking of molecular quantumdot cellular automata. All experiments were carried out in ultrahigh vacuum and at lowtemperature 77 k.
Quantumdot cellular automata qca is a lowpower, nonvonneumann, general purpose paradigm for classical computing using. This clocking field guides the data flow through the molecular qca array. Single qca molecules are characterized using ab initio quantum chemistry methods. Design and analysis of a novel lowpower exclusiveor gate. Current lines of investigation include choosing candidate molecules, 7, 21, clocking on the molecular scale 10, and circuit selfassembly 4. Realization of a functional cell for quantumdot cellular. However, it still remains a challenge to find appropriate candidate molecules for mqca operation. Molecular quantum dot cellular automata mqca is a promising transistorless paradigm that encodes binary information with bistable charge configurations instead of currents and voltages. Quantumdot cellular automata qca is a paradigm for lowpower, highspeed, highly dense computing that could be realized in a variety of materials systems.
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. A tetrairon dication featuring tetraethynylbenzene. A 3d universal structure based on molecularqca and cnt technologies. Pdf theoretical study of molecular quantum dot cellular. The interaction of the quantum mechanics with the coulomb in every cell, is the one that determines the cell state. Automatic cell placement for quantumdot cellular automata. Qca is transistorless computational paradigm which. Since its early formulation in 1993 at notre dame university, the qca idea has received significant attention and several physical implementations have been proposed. Quantumdot cellular automata qca is a lowpower, nonvon neumann, general purpose paradigm for classical computing using. The quantum cellular automaton qca concept represents an attempt to break away from the traditional threeterminal device paradigm that has dominated digital computation. 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. Molecular electronics and quantumdot cellular automata most approaches to molecular electronics have sought to reproduce conventional electronic elements, such as transistors, wires, or diodes.
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. In order to distinguish this proposal from models of cellular automata. Discussed here are the basic paradigm of qca, materials systems in which qca might be constructed, a series of. Electricfield inputs for molecular quantumdot cellular automata. Molecular quantumdot cellular automata mqca has received considerable attention in nanoscience. The main idea of quantum dot cellular automata 116 is demonstrated in fig. Molecular quantumdot cellular automata qca paradigm is a promising approach to molecular electronics. This illustrates the robustness of information encoding in the qca scheme. Signal transmission through molecular quantumdot cellular. Quantumchemical design of molecular quantumdot cellular automata qca. Our interest in mixedvalence complexes is as a potential molecular implementation of quantumdot cellular automata qca,,,, a promising approach to molecular electronics.
Pdf an introduction to the operation of quantumdot cellular automata is presented, along with recent experimental results. 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. Our studies support the experimental interpretation that this molecule has a bistable electronic state, and that binary information can be encoded in the molecular. This electronic framework therefore provides the possibility of an all. Power is dissipated in clocking wires due to the nonzero resistance of the conductors.
Eliminating wire crossings for molecular quantumdot. Quantum dot molecules for quantum cellular automata. This paper focuses on molecular quantumdot cellular automata circuits. Binary multipliers on quantumdot cellular automata 543 our pipelined array multiplier. Pdf an overview is given of the qca architecture, along with a summary of. 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. 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.
Molecular quantumdot cellular automata university of notre dame. Localization and cellcell response in tetrameric mixedvalence units andrew palii institute of applied physics, academy of sciences of moldova, kishinev, moldova. Clock topologies for molecular quantumdot cellular automata. A new molecular implementation in quantum cellular. As a replacement for cmos technology, quantum cellular automata was proposed by lent et al. Pdf clocking of molecular quantumdot cellular automata. Quantumdot cellular automata qca is a transistorless computation. Some researchers have analyzed some human body operations as equivalent to simple nano gates and their connections. Counterionfree molecular quantumdot cellular automata. We present an ab initio quantum chemistry study of. The quantum dot molecules consist of 1012 dots surrounding each.
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