THEORETICAL BASICS OF QUANTUM COMPUTATIONS

2021 ◽  
Vol 158 (3-4) ◽  
pp. 7-38
Author(s):  
Tomasz Kuczerski ◽  
Michał Dyszyński

The paper includes basic information over the domain of quantum physics needed to understand basic principles of calculations and operations with the use of quantum computers. Questions of the unit of quantum information – qubit, and the Bloch’s zone are thoroughly explained. The paper is aimed to be an introduction into the world of quantum IT for persons beyond the quantum physics who want to use the quantum algorithms for their scientific researches.

2018 ◽  
Author(s):  
Rajendra K. Bera

It now appears that quantum computers are poised to enter the world of computing and establish its dominance, especially, in the cloud. Turing machines (classical computers) tied to the laws of classical physics will not vanish from our lives but begin to play a subordinate role to quantum computers tied to the enigmatic laws of quantum physics that deal with such non-intuitive phenomena as superposition, entanglement, collapse of the wave function, and teleportation, all occurring in Hilbert space. The aim of this 3-part paper is to introduce the readers to a core set of quantum algorithms based on the postulates of quantum mechanics, and reveal the amazing power of quantum computing.


Author(s):  
Phillip Kaye ◽  
Raymond Laflamme ◽  
Michele Mosca

A computer is a physical device that helps us process information by executing algorithms. An algorithm is a well-defined procedure, with finite description, for realizing an information-processing task. An information-processing task can always be translated into a physical task. When designing complex algorithms and protocols for various information-processing tasks, it is very helpful, perhaps essential, to work with some idealized computing model. However, when studying the true limitations of a computing device, especially for some practical reason, it is important not to forget the relationship between computing and physics. Real computing devices are embodied in a larger and often richer physical reality than is represented by the idealized computing model. Quantum information processing is the result of using the physical reality that quantum theory tells us about for the purposes of performing tasks that were previously thought impossible or infeasible. Devices that perform quantum information processing are known as quantum computers. In this book we examine how quantum computers can be used to solve certain problems more efficiently than can be done with classical computers, and also how this can be done reliably even when there is a possibility for errors to occur. In this first chapter we present some fundamental notions of computation theory and quantum physics that will form the basis for much of what follows. After this brief introduction, we will review the necessary tools from linear algebra in Chapter 2, and detail the framework of quantum mechanics, as relevant to our model of quantum computation, in Chapter 3. In the remainder of the book we examine quantum teleportation, quantum algorithms and quantum error correction in detail. We are often interested in the amount of resources used by a computer to solve a problem, and we refer to this as the complexity of the computation. An important resource for a computer is time. Another resource is space, which refers to the amount of memory used by the computer in performing the computation. We measure the amount of a resource used in a computation for solving a given problem as a function of the length of the input of an instance of that problem.


MRS Bulletin ◽  
2005 ◽  
Vol 30 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Luiz Davidovich

AbstractThe following article is based on the plenary address by Luiz Davidovich (Federal University of Rio de Janeiro), presented on April 14, 2004, at the 2004 MRS Spring Meeting in San Francisco. The field of quantum information is a discipline that aims to investigate methods for characterizing, transmitting, storing, compressing, and computationally utilizing the information carried by quantum states. It owes its rapid development over the last few years to several factors: the ability, developed in several laboratories, to control and measure simple microscopic systems; the discovery of fast quantum algorithms; and the recognition that Moore's law will soon lead to the single-atom limit of elementary computing gates.Cryptography and quantum computing are among the main applications in the field.They rely on the subtle and fundamental properties of the quantum world: the unavoidable disturbance associated with measurement, the superposition principle, and the nonlocal properties of entangled states. Progress in this area is intimately connected to a deep understanding of quantum physics: recent achievements include the experimental demonstration of teleportation and detailed investigations of the role of the environment in the quantum–classical transition. This article reviews basic concepts and recent developments in the field of quantum information, emphasizing the close ties between fundamental research and possible applications.


2021 ◽  
Author(s):  
Bharadwaja V. Srividya ◽  
Smitha Sasi

The application of internet has spiked up in the present-day scenario, as the exchange of information made between two parties happens in public environment. Hence privacy of information plays an important role in our day to day life. There have been incredible developments made in the field of cryptography resulting in modern cryptography at its zenith. Quantum computers are one among them creating fear into security agencies across the world. Solving the complex mathematical calculations is uncomplicated using quantum computers which results in breaking the keys of modern cryptography, which cannot be broken using classical computers. The concept of quantum physics, into the cryptographic world has resulted in the advancement of quantum cryptography. This technique utilizes the idea of key generation by photons, and communicates between peer entities by secured channel. Quantum cryptography adapts quantum mechanical principles like Heisenberg Uncertainty principle and photon polarization principle to provide secure communication between two parties. This article focuses on generation of a secret shared key, later converted into Quantum bits (Qbits) and transmitted to the receiver securely.


Author(s):  
Ciaran Hughes ◽  
Joshua Isaacson ◽  
Anastasia Perry ◽  
Ranbel F. Sun ◽  
Jessica Turner

AbstractWe have come a long way from Chap. 10.1007/978-3-030-61601-4_1 To recap on what we have learnt, we have understood important quantum mechanical phenomena such as superposition and measurement (through the Stern-Gerlach and Mach-Zehnder experiments). We have also learnt that while quantum computers can in principle break classical encryption protocols, they can also be used to make new secure channels of communication. Furthermore, we have applied quantum logic gates to qubits to perform quantum computations. With entanglement, we teleported the information in an unknown qubit to another qubit. This is quite a substantial achievement.


2021 ◽  
Vol 158 (3-4) ◽  
pp. 49-63
Author(s):  
Tomasz Kuczerski ◽  
Włodzimierz MIKKE

An exemplary hardware platform for simulation of some elementary quantum computations is presented in the paper. Basic cards of Sinara system with software and platform for experiments in domain of quantum physics and computations were described. Some exemplary applications of the hardware platform and instruction for starting up basic quantum algorithms are presented.


Author(s):  
Ralf Stadelhofer ◽  
Wolfgang Banzhaf ◽  
Dieter Suter

AbstractAlthough it is known that quantum computers can solve certain computational problems exponentially faster than classical computers, only a small number of quantum algorithms have been developed so far. Designing such algorithms is complicated by the rather nonintuitive character of quantum physics. In this paper we present a genetic programming system that uses some new techniques to develop and improve quantum algorithms. We have used this system to develop two formerly unknown quantum algorithms. We also address a potential deficiency of the quantum decision tree model used to prove lower bounds on the query complexity of the parity problem.


Author(s):  
Dr.Seethal Peenikkal ◽  
Dr.K.Savitha R. Shenoy ◽  
Dr.Sri Nagesh K.A.

Breast Cancer is one of the most common types of malignancy among Indian woman currently. The current increase in the world wide prevalence of this disease suggests an urgent need of detailed analysis, diagnosis and treatment line through Ayurvedic principles. As cancer is least understood in technical terms of Ayurveda, Nidana Panchaka a basic tool to understand and diagnose a Vyadhi, is used to analyze it. Even though a direct diagnostic correlation of breast cancer is not available under the major Vyadhi classifications, it is possible to elicit and formulate Nidana Panchaka based on the references of Sthana Roga, Shopha, Granthi, Arbuda etc. The current article is an effort to formulate Nidana Panchaka for Breast Cancer, from the background of basic principles of Ayurveda, for a better analysis and diagnosis of the Vyadhi.


Author(s):  
Kai Li ◽  
Qing-yu Cai

AbstractQuantum algorithms can greatly speed up computation in solving some classical problems, while the computational power of quantum computers should also be restricted by laws of physics. Due to quantum time-energy uncertainty relation, there is a lower limit of the evolution time for a given quantum operation, and therefore the time complexity must be considered when the number of serial quantum operations is particularly large. When the key length is about at the level of KB (encryption and decryption can be completed in a few minutes by using standard programs), it will take at least 50-100 years for NTC (Neighbor-only, Two-qubit gate, Concurrent) architecture ion-trap quantum computers to execute Shor’s algorithm. For NTC architecture superconducting quantum computers with a code distance 27 for error-correcting, when the key length increased to 16 KB, the cracking time will also increase to 100 years that far exceeds the coherence time. This shows the robustness of the updated RSA against practical quantum computing attacks.


2021 ◽  
Vol 11 (4) ◽  
pp. 1405
Author(s):  
Nan Zhao ◽  
Tingting Wu ◽  
Yan Yu ◽  
Changxing Pei

As research on quantum computers and quantum information transmission deepens, the multi-particle and multi-mode quantum information transmission has been attracting increasing attention. For scenarios where multi-parties transmit sequentially increasing qubits, we put forward a novel (N + 1)-party cyclic remote state preparation (RSP) protocol among an arbitrary number of players and a controller. Specifically, we employ a four-party scheme in the case of a cyclic asymmetric remote state preparation scheme and demonstrate the feasibility of the scheme on the IBM Quantum Experience platform. Furthermore, we present a general quantum channel expression under different circulation directions based on the n-party. In addition, considering the impact of the actual environment in the scheme, we discuss the feasibility of the scheme affected by different noises.


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