The most important application areas are: the simulation of material properties and chemical processes; cracking cryptography; using quantum networks to distribute cryptographic keys; and solving large-scale optimisation and AI problems.
Abstract Quantum computers are designed to outperform standard computers by running quantum algorithms. Areas in which quantum algorithms can be applied include cryptography, search and optimisation, simulation of quantum systems and solving large systems of linear equations. Here we briefly survey some known quantum algorithms, with an emphasis on a broad overview of their applications rather than their technical details. We include a discussion of recent developments and near-term applications of quantum algorithms.
With the development of quantum computers, traditional cryptographic systems are facing more and more serious security threats. Fortunately, quantum key distribution (QKD) and post-quantum cryptography (PQC) are two cryptographic mechanisms with quantum-resistant security, and both will become important solutions for future information security. However, neither of them is perfect, and they are complementary. Quantum key distribution has unconditional security that post-quantum cryptography does not have, and PQC can provide secure and convenient authentication for QKD networks. In this paper, we propose two protocols based on PQC to realize the full authentication of the QKD data post-processing, and we only need to assume the short-term security of PQC algorithm to ensure the long-term quantum resistant security of distributed keys. We found that for the above two authentication protocols, attackers cannot successfully implement replay attacks. These authentication protocols can solve the problems of the current pre-shared key authentication in the application of large-scale quantum key distribution networks, and are expected to realize a key distribution mechanism with practical operability and quantum resistant security, which will be beneficial to promote the deployment and application of quantum key distribution networks.
In recent years, a significant amount of research has been conducted in the field of quantum computers. Machines that use quantum mechanical phenomena to solve mathematical problems difficult or unsolvable for ordinary computers. If large-scale quantum computers ever appear, they will be able to crack many of the currently used public key cryptosystems. This will seriously compromise the privacy and integrity of digital communications on the Internet. The goal of post-quantum cryptography (also called quantum-stable cryptography) is to develop cryptographic systems that are protected from both quantum and classical computers that can interact with existing communication protocols and networks.
With the development of quantum computing and computer science, the risk of traditional cryptographic algorithms being cracked is increasing. Therefore, quantum key distribution (QKD) technology based on quantum physical properties has been developed to ensure the security of information communication. Large-scale QKD networks can be built using trusted relay technology, but the hops encryption and decryption process of trusted relay will consume extra keys, which makes it particularly important to choose a reasonable path to reduce the consumption of extra keys during key distribution. The existing routing algorithms mainly focus on the number of remaining keys and hops, but ignore the congestion information of the network, resulting in a high key exchange failure rate and an increase in key consumption. In view of this background, we propose a load balancing routing (LBR) algorithm, which can realize congestion control in QKD network by dynamically detecting link state with SDN controller. Simulation results show that LBR improves key request success rate by more than 10% and key utilization efficiency by about 5% compared with existing methods.