A Plea for Help with Computer Architecture for Quantum Dot Cellular Automata Based Nano-Computing

Speaker: Dr Gerard Edwards, Deputy Head of Electronic & Electrical Engineering Subject Area
Venue: University of Chester, Thornton site, Room TSU115
Date: 21/2/2020 10:30 - 11:00
Audience: Staff, tenants and students interested in research


The Quantum Dot Cellular Automata (QCA) paradigm for nano-computing, put forward by the Notre Dame, USA group, manages to achieve the minimal heat dissipation and the ultimate in coding one bit, in the charge configuration state of a mixed valence molecule. The QCA paradigm is a leading contender to take over from transistor based integrated circuits, employing Complementary Metal Oxide semiconductor (CMOS) Silicon devices, in the next decade. It is the CMOS integrated circuit that allows the Information Technology revolution with ever more computationally powerful desktop PCs, laptops and smartphones.

Understanding the fundamental device physics of a QCA cell – cell response, mediated by electrostatic repulsion, is the initial step in tackling the underpinning science and engineering of a QCA based nano-computer. Current progress is being made on calculating the switching response for a pair of cells composed of a mixed valence Diferrocenylacetylene (DFA) molecules. The physical system consists of the external driver molecular and the test molecule (electronic system) being driven. However the test molecule can vibrate (vibronic modes) so this aspect must be included. The vibration system can exchange energy with the thermal environment. The density matrix for this system (a spin – boson model), whose time evolution is given by a Lindblad equation, will be calculated, giving a treatment of the molecular switching including dissipation. The Quantum Toolbox in Python (QuTip) will be used to solve for the density matrix as it has advanced features (representation of tensor operators and superoperators) designed for this purpose.

The QCA Nano-computer needs to be tackled also from a Computer Architecture systems perspective, a top down approach, to compliment the device physics bottom upwards line of attack. The basic QCA logic gate is a majority gate which can be employed to construct adder circuits. The QCADesigner Technology Computer Aided Design (TCAD) tool allows the construction of nano-computer circuits, from majority gates, using a point and click Graphical User Interface (GUI), with the device physics encapsulated in the underlying quantum mechanical description of the gates. The QCADesigner tool allows a Computer Scientist with expertise in Computer Architecture to investigate QCA Central Processor Unit (CPU) design which is essential in ushering in QCA, as the replacement technology for CMOS.


This seminar is to discuss Shareable Techniques that other researchers might find interesting and useful for their own research.

Speaker's Bio

Gerard’s research background is in theoretical semiconductor physics and solid state electronics. Gerard pursued postdoctoral work at the Centre for Solid State Electronics Research, Arizona State University (USA) and the Department of Electrical Engineering, University of Notre Dame (USA), in his late twenties/early thirties.

Gerard carried out a research collaboration from 2007 – 2011 with Prof Rong Zhang, Department of Physics, Nanjing University, PRC. Gerard provided theoretical and modelling support to Nanjing’s experimental efforts in the field of the optical properties of wide bandgap semiconductors (the underlying science for solid state lighting). This collaboration resulted in seven journal publications, four of which were successfully submitted to the REF2014 from the Renewable Energy, Materials and Devices Group, University of Bolton (UoB). While at the UoB, Gerard was also involved in providing theoretical and computer modelling/simulation support to assist the interpretation of cone calorimeter experimental results for composite material burning, carried out by collaborators Prof Baljinder Kandola & Prof Peter Myler, at the Centre for Materials Research and Innovation, UoB which resulted in three journal publications.

Gerard has cooperated with the German scientists Dr Werner Krybus and Dr Dominik Aufderheide at the South Westphalia University of Applied Sciences, Division Soest, Germany in the Computer Vision field working on Multimodal Sensor Fusion for Real Time Scene Modelling which has provided a publication that is being submitted to the Engineering Unit for the University of Chester (UoC) REF2021.

Gerard turned his attention, over the last few years, to establishing the Electronic & Electrical Engineering (EEE) Subject Area at the UoC, setting up the labs and reshaping the EEE degree, making it fit for IET Accreditation. Gerard has spawned an Exciting New Nano-electronics Research Initiative and set up the Computational Condensed Matter Physics & Nanoelectronics Research Group with Dr Theo Papadopoulos and Dr Graham Spink, at Thornton Science Park. The field of Nano-electronics is concerned with the materials, devices, circuits and systems relevant to contemporary and future integrated circuits (ICs) with feature sizes at the nanoscale i.e. nano-chips. Gerard is currently co-supervising a PhD student Mr Jack Riall on the project ‘The Calculation of the Switching of Molecular Quantum Dot Cellular Automata (QCA) for Mixed Valence Molecules’ with Dr Graham Spink, simulating a new device level nano-chip QCA technology.

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