The fundamental flaws of qubit concept for general-purpose quantum computing are elaborated here. We show that from implementing of the addition operation of two bits, only four symbolic substitution rules are needed. Superposition of four states from the two qub its is then irrelevant for the addition operation of two bits. The fundamental quantum processor needed is further described here against the quib it concept. The quantum Turing Machine is thus settled in the cellular automata architecture. Therefore, quantum computing must be rule-based, rather than logic-gate based.
The fundamental flaws of qubit concept for general-purpose quantum computing are elaborated here. We show that from implementing of the addition operation of two bits, only four symbolic substitution rules are needed. Superposition of four states from the two qub its is then irrelevant for the addition operation of two bits. The fundamental quantum processor needed is further described here against the quib it concept. The quantum Turing Machine is thus settled in the cellular automata architecture. Therefore, quantum computing must be rule-based, rather than logic-gate based.
Quantum computer is considered as a generalization of Turing machine. The bits are substituted by qubits. In turn, a "qubit" is the generalization of "bit" referring to infinite sets or series. It extends the consept of calculation from finite processes and algorithms to infinite ones, impossible as to any Turing machines (such as our computers). However, the concept of quantum computer mets all paradoxes of infinity such as Gödel's incompletness theorems (1931), etc. A philosophical reflection on how quantum computer might implement the idea of "infinite calculation" is the main subject.
In the preceding chapter we established that a suitable set of quantum gates, complemented by quantum error correction, allows us to produce a desired multiqubit unitary transformation. This transformation is one of the three steps in a quantum computation; the others, of course, are the preparation of the qubits in their initial state and the measurement of them after the transformation has been implemented. A quantum computation is designed to solve a problem or class of problems. The power of quantum computers is that they can do this, at least for some problems, very much more efficiently and quickly than any conventional computer based on classical logic operations. If we can build a quantum computer then a number of important problems which are currently intractable will become solvable. The potential for greatly enhanced computational power is, in itself, reason enough to study quantum computers, but there is another. Moore’s law is the observation that the number of transistors on a chip doubles roughly every eighteen months. A simple corollary is that computer performance also doubles on the same timescale. Associated with this exponential improvement is a dramatic reduction in the size of individual components. If the pace is to be kept up then it is inevitable that quantum effects will become increasingly important and ultimately will limit the operation of the computer. In these circumstances it is sensible to consider the possibility of harnessing quantum effects to realize quantum information processors and computers. We start with a brief introduction to the theory of computer science, the principles of which underlie the operation of what we shall refer to as classical computers. These include all existing machines and any based on the manipulation of classical bits. The development of computer science owes much to Turing, who devised a simple but powerful model of a computing device: the Turing machine. It its most elementary form, this consists of four elements. (i) A tape for data storage, which acts as a memory. This tape has a sequence of spaces, each of which has on it one of a finite set of symbols. (ii) A processor, which controls the operations of the machine.
Over the last three decades computers have become exceptionally compact and faster. Now that we have reached the fifth generation of computers which include concepts of artificial intelligence, what’s next? There is a lot of fuss about quantum computers being a strong contender for the next generation of computing. Recently we heard stories about small scale quantum computers being built by technology giants like IBM and Google and also an instance of quantum supremacy.
One of the key features of quantum computing is its core concept, leveraging the principles of quantum mechanics, which we have avoided with our classic computers. Quantum computers are the first ones to deviate from the basic concept of bits. To understand this difference in the fundamental concepts, we start with basic building blocks in conventional computers, bits and draw contrasts with those in quantum computers. Further explore how rudimentary operations are performed in both machines by comparing addition operations of 2 and 3 bits. Followed by a brief detail on current research on quantum computers and claims on their supremacy over current machines. Then we elaborate on the world of new possibilities and unsolvable problems quantum computers have the ability to tackle.
This paper aims at giving a gist of quantum computing to beginners, starting with fundamentals to current research by identifying stark contrasts with conventional machines. It also explores the need of new computation powers and why we have reached almost the tail end of processing power of classical computers.
Quantum mechanics is one of the cornerstones of modern physics. It governs the behavior and the properties of matter in a fundamental way, in particular on the microscopic scale of atoms and molecules. Hence, what we may call a classical computer, i.e., those machines on or under the desktops in our offices together with all their potential descendants, are themselves following the rules of quantum mechanics. However, they are no quantum computers in the sense that all the inside information processing can perfectly be described within classical information theory. In fact, we do not need quantum mechanics in order to explain how the zeros and ones – the bits – inside a classical computer evolve. The reason for this is that the architecture of classical computers does not make use of one of the most fundamental features of quantum mechanics, namely the possibility of superpositions. Throughout the entire processing of any program on a classical computer, each of the involved bits takes on either the value zero or one. Quantum mechanics, however, would in addition allow superpositions of zeros one ones, that is bits – now called qubits (quantum-bits) – which are somehow in the state zero and one at the
Quantum computing plays a major role in modern computation. It can perform operations exponentially faster when compared to classical computation. It has applications in various areas like secure communication, drug design, artificial intelligence, cyber security, etc. Thus, the researchers and students are showing interest to perform experiments in quantum computing to design novel architectures. But to learn/understand quantum computing, one should have strong knowledge of its basics. Because quantum computing performs operations at the atomic level, so the learners need to understand basic concepts like Qubits, superposition, quantum gates, etc. This chapter gives a clear idea about the basic concepts of quantum computing like Qubits, superposition, entanglement, and quantum gates.
Quantum computing plays a major role in modern computation. It can perform operations exponentially faster when compared to classical computation. It has applications in various areas like Secure communication, Drug design, Artificial Intelligence, Cyber security, etc. Thus the researchers and students are showing interest to perform experiments in quantum computing to design novel architectures. But to learn/understand quantum computing, one should have strong knowledge of its basics. Because quantum computing performs operations at the atomic level, so the learners need to understand basic concepts like Qubits, Superposition, Quantum gates, etc. Therefore this chapter gives a clear idea about the basic concepts of quantum computing like Qubits, Superposition, Entanglement, Teleportation, and Quantum gates.