The elementary particle of information used by modern digital computers is the bit—a register or memory element that can be in one of two distinct states, 0 or 1. But we live in a quantum world, and one can design computers in which each elementary unit of information is a quantum bit, or qubit, which can be in any superposition of two quantum states, |0〉 and |1〉. A quantum computer built with n such components could itself be in a superposition of 2n distinct states, each splinter of the superposition performing its own computation in parallel with all the rest.
The elementary particle of information used by modern digital computers is the bit—a register or memory element that can be in one of two distinct states, 0 or 1. But we live in a quantum world, and one can design computers in which each elementary unit of information is a quantum bit, or qubit, which can be in any superposition of two quantum states, |0〉 and |1〉. A quantum computer built with n such components could itself be in a superposition of 2n distinct states, each splinter of the superposition performing its own computation in parallel with all the rest.
Today's computers work on bits that exist as either 0 or 1. Quantum computers aren't limited to two states; they encode information as quantum bits, or qubits, which can exist in superposition. Qubits represent atoms, ions, photons or electrons and their respective control devices that are working together to act as computer memory and a processor. Because a quantum computer can contain these multiple states simultaneously, it has the potential to be millions of times more powerful than today's most powerful supercomputers. A processor that can use registers of qubits will be able to perform calculations using all the possible values of the input registers simultaneously. This superposition causes a phenomenon called quantum parallelism, and is the motivating force behind the research being carried out in quantum computing. Due to technical obstacles, till date, a quantum computer has not yet been realized. But the concepts and ideas of quantum computing has been demonstrated using various methods like NMR, Ion Trap, Quantum Dot, Optical Methods, etc. A quantum computer manipulates qubits by executing a series of quantum gates, each a unitary transformation acting on a single qubit or pair of qubits. In applying these gates in succession, a quantum computer can perform a complicated unitary transformation to a set of qubits in some initial state. The qubits can then be measured, with this measurement serving as the final computational result. Research must devise a way to maintain decoherence and other potential sources of error at an acceptable level. Probably the most important idea in this field is the application of error correction in phase coherence as a means to extract information and reduce error in a quantum system without actually measuring that system. Thereby, quantum computers will emerge as the superior computational devices and perhaps one day make today's modern computer obsolete.
Behold your computer. Your computer represents the culmination of years of technological advancements beginning with the early ideas of Charles Babbage (1791-1871) and eventual creation of the first computer by German engineer Konrad Zuse in 1941. Surprisingly however, the high speed modern computer sitting in front of you is fundamentally no different from its gargantuan 30 ton ancestors, which were equipped with some 18000 vacuum tubes and 500 miles of wiring! Although computers have become more compact and considerably faster in performing their task, the task remains the same: to manipulate and interpret an encoding of binary bits into a useful computational result. A bit is a fundamental unit of information, classically represented as a 0 or 1 in your digital computer. Each classical bit is physically realized through a macroscopic physical system, such as the magnetization on a hard disk or the charge on a capacitor. A document, for example, comprised of n-characters stored on the hard drive of a typical computer is accordingly described by a string of 8n zeros and ones. Herein lies a key difference between your classical computer and a quantum computer. Where a classical computer obeys the well understood laws of classical physics, a quantum computer is a device that harnesses physical phenomenon unique to quantum mechanics (especially quantum interference) to realize a fundamentally new mode of information processing. In a quantum computer, the fundamental unit of information (called a quantum bit or qubit), is not binary but rather more quaternary in nature. This qubit property arises as a direct consequence of its adherence to the laws of quantum mechanics which differ radically from the laws of classical physics. A qubit can exist not only in a state corresponding to the logical state 0 or 1 as in a classical bit, but also in states corresponding to a blend or superposition of these classical states. In other words, a qubit can exist as a zero, a one, or simultaneously as both 0 and 1, with a numerical coefficient representing the probability for each state. This may seem counterintuitive because everyday phenomenon are governed by classical physics, not quantum mechanics – which takes over at the atomic level. This rather difficult concept is perhaps best explained through an experiment. Consider Figure 1 below:
Computer technology fundamentally works as on/off switches. These switches are digits: 1s and 0s; 1s are on, 0s are off. In computerese these switchable binary digits are called bits. Quantum computing utilizes subatomic bits, or “qubits,” that can exist as a 1 or a 0 or as both simultaneously. Quantum computers use quantum-mechanical interactions that allow amazing calculating power. The chief advantage of a quantum computer is that it can be in multiple states simultaneously, known as “superposition,” while also simultaneously acting on each possible state. A quantum computer could therefore perform innumerable calculations in parallel using only one processing unit.
The quantum world is fascinating. It presents a description of nature that defies our most rooted concepts about what reality is. For example, quantum objects possess \lq\lq spooky\rq\rq\ properties that allow them to be in multiple places at the same time, to move in different directions simultaneously, or to exist and not to exist. In other words, to live several parallel stories. Making use of these parallel stories to compute is the realm of quantum computation, a world in which information is processed using the laws of quantum physics. Nowadays, quantum computers are an object of an extensive experimental and theoretical research, since it is known that, on paper, these can solve many of the current computational challenges. These are the problems that even the most sophisticated supercomputers of today, or tomorrow, will not be able to solve.
The article is devoted to the actual problem of teaching methods of the subjects of the educational process of modern information and computer science. The contribution of Ukrainian scientists to the development of electronic computing machines, their programming and teaching methods, prospects for further research are briefly considered. In the natural sciences, elementary units are widely used for various measurements. In particular, Planck’s constant is the smallest portion, quantum of energy, quantum of action, which is used in quantum mechanics. It is also known from the course of physics that the smallest portion of energy in classical mechanics is the energy per one degree of freedom. Logically created mathematical models and theories describing the relevant properties of matter using the specified units. Similarly, emphasis is placed on clarifying the difference between a classical computer and quantum units of information. The concepts of bit of information, qubit and trit are revealed, and depending on the defined units of information, types of computers are distinguished: classical and quantum. The concepts of qubit and trit are considered mainly as a mathematical entity, and attention is not focused on the content of the physics of quantum objects, a comparison of the indicated units of quantum information with a traditional bit of information in the quantum world is given. A historical-genetic analysis of the registers of elementary logic systems, a theoretical study of the principles of superposition and interaction between quantum states, and experimental methods of implementing qubits and their connections have been carried out. An important field for the use of quantum computers is cryptology, for solving the problems of which Grover’s method has already been created. With Grover’s quantum algorithm, it is possible to quickly search for the necessary element in an unsorted database with 2nN (n is the length of the search space of the quantum register - the number of qubits in it; N is the size of the search space). However, although the quantum simulator gives a high probability of the correct result, experimental studies also show large discrepancies. Therefore, there is a problem for further research. Quantum computers can influence each other through the phenomenon of entanglement.
Quantum computing makes use of wave-function superposition to provide a computational system with remarkable possibilities. A computing bit is a 0 or 1, but a quantum bit, a qubit, is a superposition of two quantum states, of, say, an atom. A number n of qubits will then be in a superposition of 2n distinct states. An operation on such a state then does 2n simultaneous operations, demonstrating quantum parallelism. The possibilities of quantum computing are demonstrated via discussion of Deutch’s problem, Shor’s period-finding algorithm, and Grover’s search algorithm. Shor’s algorithm might allow the factoring of large numbers, which might enable the decoding of many encryption schemes. Details are given for the solution of Deutch’s problem. The analysis introduces certain operators, the NOT and Hadamard, that are used in computer logic.