Effectiveness of Molecules for Quantum Cellular Automata as Computing Devices

Yuri Ardesi,Gianluca Piccinini,Mariagrazia Graziano,Fabrizio Riente,Azzurra Pulimeno

doi:10.3390/jlpea8030024

Abstract

Notwithstanding the increasing interest in Molecular Quantum-Dot Cellular Automata (MQCA) as emerging devices for computation, a characterization of their behavior from an electronic standpoint is not well-stated. Devices are typically analyzed with quantum physics-based approaches which are far from the electronic engineering world and make it difficult to design, simulate and fabricate molecular devices. In this work, we define new figures of merits to characterize the molecules, which are based on the post-processing of results obtained from ab initio simulations. We define the Aggregated Charge (AC), the electric-field generated at the receiver molecule (EFGR), the Vin–Vout and Vin–AC transcharacteristics (VVT and VACT), the Vout maps (VOM) and the MQCA cell working zones (CWZ). These quantities are compatible with an electronic engineering point of view and can be used to analyze the capability of molecules to propagate information. We apply and verify the methodology to three molecules already proposed in the literature for MQCA and we state to which extent these molecules can be effective for computation. The adopted methodology provides the quantitative characterization of the molecules necessary for digital designers, to design digital circuits, and for technologists, to the future fabrication of MQCA devices.

Highlights

The high switching frequency associated to the reduced power dissipation, which is ensured by the absence of electrical conduction, is the most attracting feature of Molecular Quantum-dot Cellular Automata (MQCA) [1,2] that proposes it as a potential emerging technology for computation
We define new figures of merits such as the Aggregated Charge (AC), the electric-field generated at the receiver molecule (EFGR), the Vin–Vout transcharacteristics (VVT), the Vin–AC transcharacteristics (VACT), the Vout maps (VOM) and the MQCA cell working zones (CWZ)
The molecular implementation of Field-Coupled Nanocomputing, known as Molecular Quantum-dot Cellular Automata, has been assessed as a possible technology to overcome the issues related to CMOS scaling

Summary

Introduction

The high switching frequency associated to the reduced power dissipation, which is ensured by the absence of electrical conduction, is the most attracting feature of Molecular Quantum-dot Cellular Automata (MQCA) [1,2] that proposes it as a potential emerging technology for computation. By aligning cells on a line, it is possible to obtain QCA wires that propagate the logic information from a point to another [4,5]. No electrical current is involved in the propagation of the logic information; this property limits the power consumption and represents the most interesting feature of these devices, especially if compared to scaled CMOS circuits and their current trend in terms of power dissipation [6]. In order to enhance the performance of the MQCA cell, the molecule should be considered in the oxidized or reduced form. In the former case, one electron is missing and the molecule has a net positive charge; while in the latter case an additional electron is available and the molecule has a net negative charge

Methods

Results

Conclusion