IET Quantum Communication最新文献

In recent years, numerous research advancements have extended the limit of classical simulation of quantum algorithms. Although, most of the state-of-the-art classical simulators are only limited to binary quantum systems, which restrict the classical simulation of higher-dimensional quantum computing systems. Through recent developments in higher-dimensional quantum computing systems, it is realised that implementing qudits improves the overall performance of a quantum algorithm by increasing memory space and reducing the asymptotic complexity of a quantum circuit. Hence, in this article, QuDiet, a state-of-the-art user-friendly python-based higher-dimensional quantum computing simulator is introduced. QuDiet offers multi-valued logic operations by utilising generalised quantum gates with an abstraction so that any naive user can simulate qudit systems with ease as compared to the existing ones. Various benchmark quantum circuits is simulated in QuDiet and show the considerable speedup in simulation time as compared to the other simulators without loss in precision. Finally, QuDiet provides a full qubit-qudit hybrid quantum simulator package with quantum circuit templates of well-known quantum algorithms for fast prototyping and simulation. Comprehensive simulation up to 20 qutrits circuit on depth 80 on QuDiet was successfully achieved. The complete code and packages of QuDiet is available at https://github.com/LegacYFTw/QuDiet.

With the race to build large-scale quantum computers and efforts to exploit quantum algorithms for efficient problem solving in science and engineering disciplines, the requirement to have efficient and scalable verification methods are of vital importance. A novel formal verification method that is targeted at Quantum Fourier Transform (QFT) circuits is proposed. Quantum Fourier Transform is a fundamental quantum algorithm that forms the basis of many quantum computing applications. The verification method employs abstractions of quantum gates used in QFT that leads to a reduction of the verification problem from Hilbert space to the quantifier free logic of bit-vectors. Very efficient decision procedures are available to reason about bit-vectors. Therefore, this method is able to scale up to the verification of QFT circuits with 10,000 qubits and 50 million quantum gates, providing a meteoric advance in the size of QFT circuits thus far verified using formal verification methods.

Classical Cryptography has been in use for a long time. It has been the only way of securing people's communication. However, there are some flaws observed during the execution of classical cryptography. One of them being the staunch belief that the number composed of multiplication of two large prime numbers cannot be factorised easily, which is under a threat thanks to the computational power of the quantum computers. The next flaw is the non-detection of the hacker, both of which can be eliminated by using quantum mechanical principles for encryption purposes, which is known as quantum cryptography. Quantum Key Distribution, which provides an information-theoretically safe solution to the key exchange problem, is the most well-known example of quantum cryptography. The benefit of quantum cryptography is that it makes it possible to perform a variety of cryptographic operations that have been demonstrated or are hypothesised to be impractical when using solely traditional (i.e., non-quantum) communication. Free-space quantum communication has been successfully demonstrated across 300 m by the Indian Space Research Organization (ISRO) in March 2021. With this, ISRO is trying to achieve the same using a satellite-based communication mechanism, which would revolutionise the mode of modern communication. It is justified that the key generation rate depends on factors like the aperture diameter of the sender and receiver, distance between them, the quantum bit error rate, and many more. The results vary with the parameters in the discussion as explained in the upcoming sections. The avenue of different types of losses that occur while transmitting at large distances, such as Atmospheric Loss, Pointing Loss and Geometric Loss, is explored.

Physics systems are becoming increasingly complex and require more and more computing time. Quantum computing, which has shown its efficiency on some problems, such as the factorisation of a number with Shor's algorithm, may be the solution to reduce these computation times. Here, the authors propose two quantum numerical schemes for the simulation of physics phenomena, based on the finite difference method. The aim is to see if quantum versions of standard numerical schemes offer an advantage over their classical counterparts, either in accuracy, stability or computation time. First, the authors will present the different phenomena studied as well as the classical solution methods chosen. The authors will then describe the implementation of the quantum numerical schemes and present some results obtained on the different physics phenomena beforehand and then compare both approaches, classical and quantum.

The combination of quantum communication technology and wireless networks brings a flexible and secure communication method that adapts to a more complex and open network environment. A new multi-hop teleportation scheme is investigated for transferring arbitrary unknown multi-qudit states between two distant parties. Based on a more general quantum routing protocol, intermediate nodes are introduced and linked with each other via d-level entangled Greenberger-Horne-Zeilinger states as quantum channels. In this multi-hop teleportation protocol, the source node and all the intermediate nodes can perform the entanglement measurement and transmit the measurement results simultaneously, thus reducing the time consumption largely. Furthermore, a general matrix formula is derived between the measurement results and the receiver's state, which enables the receiver to restore the unknown state efficiently. Compared with previous multi-hop teleportation protocols, the teleportation protocol of arbitrary unknown multi-qudit states of the authors can transfer more information, and it demonstrates lower computational complexity and higher flexibility.

Wireless Sensor Networks (WSNs) due to their numerous applications have become a significant research topic in recent years, which include monitoring, tracking/detection, medical, military surveillance, and industrial. Due to the small sensors' difficulty in being easily recharged after random deployment, energy consumption is a challenging research problem for WSNs in general. One popular scenario for reducing energy consumption for WSNs is to use cluster-based technology to reduce sensor node communication distance. Along with focusing on the Chain Cluster Based routing protocol classes. Initially, the Calinski Harabasz approach is utilized to find the optimum number of clusters. This modification will take place for two stages that pass via improving techniques of enhancing the Improved Energy-Efficient PEGASIS-Based (IEEPB) protocol to achieve the main goal of this study. The network lifetime was then extended by using the K-means algorithm. As a result, rather than using a single long path, data is transferred over shorter parallel lines. The protocol is simulated with the MatlabR2015b simulator, which produces clear and effective simulation results, particularly in terms of energy savings. The outcome of the simulation results shows that the Improved energy-efficient PEGASIS-based routing protocol- KMeans optimisation (Improved EEPB- K-means Optimisation) protocol outperforms the Low-energy adaptive clustering hierarchy, Power-efficient gathering in sensor information systems, IEEPB, and MIEEPB protocols.

The Kolmogorov complexity of a string is the minimum length of a programme that can produce that string. Information distance between two strings based on Kolmogorov complexity is defined as the minimum length of a programme that can transform either string into the other one, both ways. The second quantised Kolmogorov complexity of a quantum state is the minimum average length of a quantum programme that can reproduce that state. In this paper, a second quantised information distance is defined based on the second quantised Kolmogorov complexity. It is described as the minimum average length of a transformation quantum programme between two quantum states. This distance's basic properties are discussed. A practical analogue of quantum information distance is also developed based on quantum data compression.

In this paper, a modified formulation of generalised probabilistic theories that will always give rise to the structure of Hilbert space of quantum mechanics, in any finite outcome space, is presented and the guidelines to how to extend this work to infinite dimensional Hilbert spaces are given. Moreover, this new formulation which will be called as extended operational-probabilistic theories, applies not only to quantum systems, but also equally well to classical systems, without violating Bell's theorem, and at the same time solves the measurement problem. A new answer to the question of why our universe is quantum mechanical rather than classical will be presented. Besides, this extended probability theory shows that it is non-determinacy, or to be more precise, the non-deterministic description of the universe, that makes the laws of physics the way they are. In addition, this paper shows that there is still a possibility that there might be a deterministic level from which our universe emerges, which if understood correctly, may open the door wide to applications in areas such as quantum computing. In addition, this paper explains the deep reason why complex Hilbert spaces in quantum mechanics are needed.