Quantum computing is an emerging technology with the potential to have a significant impact on science and society. Recent advances in mathematics, material science and computer engineering are transforming quantum computing from theory into practice. As quantum computing is an entirely different concept compared to classical computing, it is necessary to develop a new way of thinking to establish the new technologies for the current quantum revolution. This book is an essential resource for students and active researchers where the readers are introduced to quantum computing and quantum logic, fault tolerant quantum computing and quantum dot cellular automata (QCA).

Quantum circuits are the building blocks of a quantum computer, and the design of quantum circuits, including the adder, multiplier, divider, encoder, decoder, barrel shifter, comparator and arithmetic logic units are discussed. Quantum error correction and fault-tolerant quantum computation represent one of the most vital challenges of quantum information processing. Fault tolerant circuits are requited, which will allow the qubits to be protected from quantum errors due to uncontrolled interactions with the environment or imperfect implementations of quantum logical operations. Including designs of fault tolerant quantum circuits such as adder, multiplier and divider, this book provides readers with a clear perspective on the topic.

Quantum dot cellular automata is a new computational paradigm which encodes binary information by charge configuration within a cell instead of the conventional current switches. As there is no current flow, the columbic interaction is sufficient for computation. This revolutionary paradigm provides a possible solution for transistor-less computation at the nano-scale. Through this book readers will acquire knowledge of QCA and the design processes of different quantum circuits using QCA designing software. Coverage also extends to the cost of QCA circuits which includes cell area, delay, kink energy and power.

Professor Rd. Hafiz Md. Hasan Babu is currently the Pro -Vice-Chancellor of National University, Bangladesh. He also served as the Professor and former Chairman of the Department of Robotics and Mechatronics Engineering, University of Dhaka , Bangladesh. He received his M.Sc. degree in Computer Science and Engineering from the Brno University of Technology, Czech Republic in 1992 and his PhD from the Kyushu Institute of Technology, Japan in 2000. He has written more than one hundred research articles and a regular reviewer of reputed International Journals and International Conferences and associate Editor of "Computer and Digital Techniques" published by the Institution of Engineering and Technology of the United Kingdom. Professor dir. Hasan was appointed as a member of the Prime Minister's ICT Task Force Committee, Government of the People's Republic of Bangladesh on recognition of his national and international level contributions in Engineering Sciences. He is currently the President of Bangladesh Computer Society and the President of Internet Society, Bangladesh Chapter.

Part I Quantum Logic

1 Quantum Logic

2 Basic Definitions of Quantum Logic

3 Quantum Bit String Comparator

4 Quantum Full-adder and Subtractor

5 Quantum Multiplexer and Demultiplexer

6 Quantum Adders Circuits

7 Quantum Multiplier Accumulator

8 Quantum Divider

9 Quantum BCD Priority Encoder

10 Quantum Decoder

11 Quantum Square Root Circuit

12 Quantum Latches and Counter Circuits

13 Quantum Controlled Ternary Barrel Shifter

14 Quantum Random Access Memory

15 Quantum Arithmetic Logic Unit

16 Applications of Quantum Computing Technology

Part II Quantum Fault Tolerant

17 Quantum Fault Tolerant Circuit

Part III Quantum-Dot Cellular Automata

18 Quantum-Dot Cellular Automata

19 QCA Adder and Subtractor

20 QCA Multiplier and Divider

21 QCA Asynchronous and Synchronous Counter

22 QCA Decoder and Encoder

23 QCA Multiplexer and Demultiplexer

24 QCA RAM Cell, ROM and Processor