Effectiveness of Molecules for Quantum Cellular Automata as Computing Devices

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.

Characterisation of a bis‐ferrocene molecular QCA wire on a non‐ideal gold surface

“…2.1. 'MoSQuiTo' suite: The molecular simulator quantum-dot cellular automata Torino suite ('MoSQuiTo') is implemented to model MQCA as electronic devices [11,12]. It introduces figures of merits to demonstrate the ability of MQCA devices to perform the computation.…”

“…Stage II : the electrostatic properties of MQCA systems are analysed defining the Aggregated Charge and the Input‐Voltage as figure of merits [12], evaluated with Octave [14] by post‐processing simulation data [11]. To be specific, the aggregated charge is calculated based on the obtained atomic charges [15] which are spatially collected in three groups, representing the dots, and summed up to obtain the aggregated charge distribution of the bis‐ferrocene molecule.…”

“…The relation between the charge distribution and the is described using the V in ‐aggregated charge transcharacteristics (VACT), figure of merit which links the input voltage with the value of the aggregated charges [12]. An alternative transcharacteristics to describe the interaction between two molecules was evaluated analytically in [16], in the present work we use the VACT because it is evaluated directly with ab initio simulation and it enables the evaluation of molecule polarisation considering the influence of all the molecules of the wire.…”

Router design for nano‐communication using actin quantum cellular automata

“…Actin filament networks can act as a computational medium where different cell structures of actin are used for developing the logical concept [30]. AQCA concept is also capable of describing the effectiveness of molecules and the design of digital circuitry [31].…”

Editorial for the Special Issue on “Quantum-Dot Cellular Automata (QCA) and Low Power Application”

“…In the paper entitled "Effectiveness of Molecules for Quantum Cellular Automata as Computing Devices" [4], Professors Ardesi, Pulimeno, Graziano, Riente, and Piccinini define new figures of merit to characterize the molecules, which are based on the post-processing of results obtained from ab initio simulations. These quantities are compatible with an electronic engineering point of view and can be used to analyze the capability of molecules to propagate information.…”