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The ability to control the optical properties of a material with an electric field has led to optical memory devices, communication systems, optical signal processing, or quantum cryptography. Understanding electro-optic effects, especially in thin films, would improve the efficiency of these applications. In particular, the influence of epitaxial strains is of prime importance. In addition, the active control of these effects would be of great interest to tailor the material to the desired performance. Here, we demonstrate through first-principle calculations that the linear electro-optic response (Pockels effect) of two silicon-compatible ferroelectrics is stable with respect to bi-axial strain and that the electro-optic response can be strongly enhanced through the electrical control of the polarization. We attribute the former to the lack of optical phonon softening and a weak elasto-optic response and the latter to the externally induced softening of a phonon of symmetry A 1. Our results are readily applicable to other polar materials and show that the electro-optic effect can be efficiently engineered to meet the performance criteria of future technologies. [ABSTRACT FROM AUTHOR]

Shor's factorization algorithm (SFA) aims at finding the non-trivial factor of a given composite number, but the algorithm does not always work. In some cases, it has to call back to the beginning of the algorithm to make recalculation. After the analysis of the principle of SFA and the characteristics of RSA public-key cryptography with a series of data calculations, it can be concluded that the random value selected by the algorithm is closely related to whether the obtained period is effective. Therefore, a new optimized scheme is proposed to tackle with this defect from two perspectives: (a) When the a value is a perfect square, the algorithm can be completed with an odd cycle r. (b) When the period r obtained by the randomly selected a value is a multiple of 3 , the algorithm can be completed by modifying the decomposition method to relax the requirements for the period without affecting the complexity of the algorithm. Due to the limitations of hardware in applying the quantum algorithms, the classical algorithm is applied to simulate quantum algorithms to test the success rate of decomposition of some composite numbers. The result indicates the effectiveness of the improved algorithm, which significantly reduces the probability of repeated operations to save the quantum circuit resources. [ABSTRACT FROM AUTHOR]

These are exciting times for quantum physics as new quantum technologies are expected to soon transform computing at an unprecedented level. Simultaneously network science is flourishing proving an ideal mathematical and computational framework to capture the complexity of large interacting systems. Here we provide a comprehensive and timely review of the rising field of complex quantum networks. On one side, this subject is key to harness the potential of complex networks in order to provide design principles to boost and enhance quantum algorithms and quantum technologies. On the other side this subject can provide a new generation of quantum algorithms to infer significant complex network properties. The field features fundamental research questions as diverse as designing networks to shape Hamiltonians and their corresponding phase diagram, taming the complexity of many-body quantum systems with network theory, revealing how quantum physics and quantum algorithms can predict novel network properties and phase transitions, and studying the interplay between architecture, topology and performance in quantum communication networks. Our review covers all of these multifaceted aspects in a self-contained presentation aimed both at network-curious quantum physicists and at quantum-curious network theorists. We provide a framework that unifies the field of quantum complex networks along four main research lines: network-generalized, quantum-applied, quantum-generalized and quantum-enhanced. Finally we draw attention to the connections between these research lines, which can lead to new opportunities and new discoveries at the interface between quantum physics and network science. [ABSTRACT FROM AUTHOR]

Local hidden-variable model of singlet-state correlations discussed in Czachor (Acta Phys Polon A 139:70, 2021a) is shown to be a particular case of an infinite hierarchy of local hidden-variable models based on an infinite hierarchy of calculi. Violation of Bell-type inequalities can be interpreted as a 'confusion of languages' problem, a result of mixing different but neighboring levels of the hierarchy. Mixing of non-neighboring levels results in violations beyond the Tsirelson bounds. [ABSTRACT FROM AUTHOR]

Large number factorization is not only the most critical entry point for Rivest–Shamir–Adleman (RSA) security analysis, but also the most direct means of attacking the asymmetric encryption algorithm RSA. In this paper, the factorization methods of large numbers are summarized and analysed: classical integer factoring algorithms, Shor's circuit model algorithm, quantum adiabatic methods (integer factorization based on a quantum nuclear magnetic resonance (NMR) platform and D-Wave quantum annealing), and hybrid quantum-classical computing. Finally, the feasibility of integer factorization based on quantum adiabatics is discussed. In this paper, quantum annealing is regarded as a quantum attack method that is completely different from the famous Shor algorithm, and the potential of D-Wave factorization of large numbers to crack RSA cryptography is verified, which provides a new idea for a quantum attack on RSA public key cryptography. [ABSTRACT FROM AUTHOR]

The Internet of Things and Quantum Computing raise concerns, as Quantum IoT defines security that exploits quantum security management in IoT. The security of IoT is a significant concern for ensuring secure communications that must be appropriately protected to address key distribution challenges and ensure high security during data transmission. Therefore, in the critical context of IoT environments, secure data aggregation can provide access privileges for accessing network services. "Most data aggregation schemes achieve high computational efficiency; however, the cryptography mechanism faces challenges in finding a solution for the expected security desecration, especially with the advent of quantum computers utilizing public-key cryptosystems despite these limitations. In this paper, the Secure Data Aggregation using Quantum Key Management scheme, named SDA-QKM, employs public-key encryption to enhance the security level of data aggregation. The proposed system introduces traceability and stability checks for the keys to detect adversaries during the data aggregation process, providing efficient security and reducing authentication costs. Here the performance has been evaluated by comparing it with existing competing schemes in terms of data aggregation. The results demonstrate that SDA-QKM offers a robust security analysis against various threats, protecting privacy, authentication, and computation efficiency at a lower computational cost and communication overhead than existing systems. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an efficient single-state three-party quantum key agreement (QKA) protocol. We proved that the protocol can resist potential outside attacks and inside attacks, and we generalized the efficient single-state three-party QKA scheme into the case of the N-party by substituting N-particle entangled state for three-particle entangled state as the resource quantum states. Compared with the previous QKA protocols, our scheme contains the good features of previous schemes, i.e., using one kind of maximally entangled states as the quantum resource, no requirements for pre-shared key between different participants, and no requirements for executing any unitary operations or quantum entanglement swapping. Furthermore, our scheme has significant improvements in terms of the times of quantum states transmission, the consumed qubits, and the qubit efficiency. In particular, as the number of participants increases, the number of qubits required by our scheme increases linearly rather than exponentially. [ABSTRACT FROM AUTHOR]

Secure quantum multiparty computation is an important field of quantum computing. Many of the preceding aggregation approaches are (n, n) threshold-dependent strategies, where n denotes the total number of participants. The previous aggregating techniques cannot aggregate the secret effectively if one participant is dishonest. This paper presents a quantum technique for secure aggregation. This technique is (t, n) threshold-dependent scheme, where t is the threshold number of participants. We used the properties of quantum mechanics to provide security in quantum aggregation. This technique can compute the aggregation of secrets securely with less computation and communication costs. The proposed aggregation technique is efficient and secure as compared to existing techniques. The simulation results of the proposed technique ensure correctness and practicality. [ABSTRACT FROM AUTHOR]

In the last two decades, structured light patterns with orbital angular momentum (OAM) have been extensively utilized in quantum cryptography or quantum key distribution (QKD), which is generally considered an unconditionally secure method of a secret key transmission between two distant communicating entities. High-dimensional encoding of quantum bits in quantum key distribution improves the security and information-carrying capability of a quantum signal. However, the free space optical channel significantly degrades the efficiency of such communication due to the aberration of OAM states under atmospheric turbulence. This paper focuses on analyzing the impact of atmospheric turbulence on QKD error-rates. These aid in analyzing the security of such communication over the quantum channel in the presence of an intruder (man-in-the-middle). Our results showed that the turbulence under normal conditions does not significantly affect the successful transmission of secret quantum bits between sender and receiver. Furthermore, our results show a unique pattern of variation in the quantum bit error rate, index transmission error rate and efficiency that helps to clearly detect the presence of an intruder as a result of medium-level turbulence. [ABSTRACT FROM AUTHOR]

The aim of device-independent quantum key distribution (DIQKD) is to study protocols that allow the generation of a secret shared key between two parties under minimal assumptions on the devices that produce the key. These devices are merely modeled as black boxes and mathematically described as conditional probability distributions. A major obstacle in the analysis of DIQKD protocols is the huge space of possible black box behaviors. De Finetti theorems can help to overcome this problem by reducing the analysis to black boxes that have an iid structure. Here we show two new de Finetti theorems that relate conditional probability distributions in the quantum set to de Finetti distributions (convex combinations of iid distributions) that are themselves in the quantum set. We also show how one of these de Finetti theorems can be used to enforce some restrictions onto the attacker of a DIQKD protocol. Finally we observe that some desirable strengthenings of this restriction, for instance to collective attacks only, are not straightforwardly possible. [ABSTRACT FROM AUTHOR]

Edge computing (EC) aided Internet of Things (IoT) based applications require real-time processing as well as high-volume data-intensive services as 5G networks evolve. It is difficult to fit IoT services into available edge nodes (ENs) while maintaining performance measures on quality of service (QoS) because of the heterogeneity, restricted resources, and changing resource demand of IoT applications. This study aims to examine a quantum healthcare model that is built on mobile edge computing networks linked with smart IoT. Serverless computing with edge computing may handle quick or small-scale tasks effectively at edge devices, lowering latency. Moreover, serverless edge computing now faces significant hurdles from security and processing performance. In order to provide trustworthy and secure edge serverless services, it is possible to use blockchain technology to boost processing speed and quantum computing to enhance security. In terms of decreasing dependency on IoT cloud analytics or storage facilities, the test results were promising. Lastly, we cover the many aspects that impact the viability of integrating an edge-IoT ecosystem, such as design, capability requirements, functional challenges, and selection criteria. [ABSTRACT FROM AUTHOR]

It is known that the Frenet–Serret apparatus of a space curve in three-dimensional Euclidean space determines the local geometry of curves. In particular, the Frenet–Serret apparatus specifies important geometric invariants, including the curvature and the torsion of a curve. It is also acknowledged in quantum information science that low complexity and high efficiency are essential features to achieve when cleverly manipulating quantum states that encode quantum information about a physical system. In this paper, we propose a geometric perspective on how to quantify the bending and the twisting of quantum curves traced by dynamically evolving state vectors. Specifically, we propose a quantum version of the Frenet–Serret apparatus for a quantum trajectory in projective Hilbert space traced by a parallel-transported pure quantum state evolving unitarily under a stationary Hamiltonian specifying the Schrödinger equation. Our proposed constant curvature coefficient is given by the magnitude squared of the covariant derivative of the tangent vector | T 〉 to the state vector | Ψ 〉 and represents a useful measure of the bending of the quantum curve. Our proposed constant torsion coefficient, instead, is defined in terms of the magnitude squared of the projection of the covariant derivative of the tangent vector | T 〉 , orthogonal to both | T 〉 and | Ψ 〉. The torsion coefficient provides a convenient measure of the twisting of the quantum curve. Remarkably, we show that our proposed curvature and torsion coefficients coincide with those existing in the literature, although introduced in a completely different manner. Interestingly, not only we establish that zero curvature corresponds to unit geodesic efficiency during the quantum transportation in projective Hilbert space, but we also find that the concepts of curvature and torsion help enlighten the statistical structure of quantum theory. Indeed, while the former concept can be essentially defined in terms of the concept of kurtosis, the positivity of the latter can be regarded as a restatement of the well-known Pearson inequality that involves both the concepts of kurtosis and skewness in mathematical statistics. Finally, not only do we present illustrative examples with nonzero curvature for single-qubit time-independent Hamiltonian evolutions for which it is impossible to generate torsion, but we also discuss physical applications extended to two-qubit stationary Hamiltonians that generate curves with both nonzero curvature and nonvanishing torsion traced by quantum states with different degrees of entanglement, ranging from separable states to maximally entangled Bell states. In the Appendix C, we examine the different curvature and torsion characteristics of the three qubit | GHZ 〉 and | W 〉 states under evolution by a quantum Heisenberg Hamiltonian. [ABSTRACT FROM AUTHOR]

Nowadays, pairing-based cryptography researchers are looking for new parameters for standard security levels against the new number field sieve tower number field sieve algorithm. Recently, they have suggested new parameters for well-studied pairing-friendly curves with odd embedding degrees five and seven resistant to this attack. In this paper, we define optimal ate pairing on curves using sparse families with embedding degrees five and seven. We also provide details to perform the miller loop and the final exponentiation using addition chain process. Our theoretical results costs indicate that these families of curves offer the best performance in the computation of the optimal ate pairing at the 128-bit security level compared to Cocks–Pinch curves of embedding degrees five and seven. The improvement is about 8 , 8 % and 1 9 % faster than the optimal ate pairing previously computed on Cocks–Pinch curves of embedding degrees five and seven, respectively. [ABSTRACT FROM AUTHOR]

This study identifies a participant attack vulnerability in Li et al.'s SQPC protocol. The participant attack allows a malicious participant, Bob, to obtain the participant Alice's secret information by intercepting and measuring photons sent to Alice, and later decrypting Alice's encrypted comparison result. An improved SQPC protocol is proposed to address this problem. The key enhancement is introducing a mutual eavesdropping check requiring the third party and participants to verify they obtain the same photon measurement results. This enables detecting participant attacks like the one identified. The SQPC protocol proposed in this study not only withstands attacks from internal participants but also achieves quantum efficiency almost equivalent to Li et al.'s SQPC protocol. Thus, this study presents a more secure SQPC protocol without compromising quantum efficiency. [ABSTRACT FROM AUTHOR]

This paper puts forward a novel quantum dialogue (QD) protocol without information leakage based on single photons in both polarization and spatial-mode degrees of freedom. In this protocol, the receiver sends his private message to the sender in the way of quantum secure direct communication; and the receiver decodes out the private message of the sender with the help of auxiliary single photons in two degrees of freedom, double controlled-not (CNOT) operations and an auxiliary classical bit sequence sent from the sender. As a result, no information leakage takes place. Moreover, this protocol is proven to defeat the intercept-resend attack, the measure-resend attack, the entangle-measure attack and the Trojan horse attack from an outside eavesdropper. This protocol only employs single photons in two degrees of freedom as quantum resource and needs single-photon measurements. The qubit efficiency of this protocol is as high as 66.7%. [ABSTRACT FROM AUTHOR]

Quantum network allows communication among more than two users with quantum teleportation and high quantum fidelity enabled by non-classical resources. As one of the most versatile architectures, all users are connected mediated by the central station in the star topology network, leading to the realization of the information interconnection and interoperability. In this work, we experimentally demonstrate a 4-branch continuous variable (CV) quantum teleportation network with star topology by employing entangled sideband modes from one squeezed state of light. Here, multiple pairs of entangled sideband modes are distributed on demand to central station and four nodes, respectively. Each node linked to the network has its own communication channel with the central station, where the deterministic CV quantum teleportation protocol is implemented with the fidelities above 0.830. [ABSTRACT FROM AUTHOR]

Quantum photonic platforms have proven to be essential in realizing fundamentally secure quantum transfer of information, with commercially ready systems already deployed in municipal and terrestrial links. The drive toward higher bit rates and robustness to eavesdropping and noisy channels has focused attention on moving from the present two-dimensional quantum states of polarization, to harnessing all of light's degrees of freedom for multi-dimensional quantum coding with structured photons. In this Perspective, we outline the present state-of-the-art in achieving this control with spatial modes of light, both as single photon and entangled states, highlight the open challenges that remain, and consider the roadmap that might see its full potential realized. [ABSTRACT FROM AUTHOR]

This paper promotes reinforcement machine learning for route-finding tasks in quantum communication networks, where, due to the non-additivity of quantum errors, classical graph path or tree-finding algorithms cannot be used. We propose using a proximal policy optimization algorithm capable of finding routes in teleportation-based quantum networks. This algorithm is benchmarked against the Monte Carlo search. The topology of our network resembles the proposed 6 G topology and analyzed that quantum errors correspond to typical errors in realistic quantum channels. [ABSTRACT FROM AUTHOR]

The quantum permutation pad (QPP) is a cryptographic primitive, functionally similar to the one-time pad (OTP). Unlike OTP, QPP promises to remain secure even when the encryption key is used multiple times (Kuang and Barbeau in Quantum Inf Process 21(6):211, 2022. https://doi.org/10.1007/s11128-022-03557-y). QPP has emerged as a relatively recent proposal, with many aspects of its functionality yet to be explored. One such aspect is ensuring the security of this primitive against chosen-plaintext attacks. This study reveals that an eavesdropper can gain access to the encryption key under such an attack paradigm. Additionally, the security of a proposed practical encryption device built around PRNG and QPP primitives is examined (Kuang and Perepechaenko in EPJ Quantum Technol 9(1):26, 2022. https://doi.org/10.1140/epjqt/s40507-022-00145-y). We have found that simplified versions, in which the attacker has access to the input data of the QPP block, are vulnerable. It is crucial to note, however, that the described attack does not undermine the security of a complete implementation, as it requires a combined attack on both the PRNG and QPP. [ABSTRACT FROM AUTHOR]

Genuine multipartite entanglement is crucial for quantum information and related technologies, but quantifying it has been a long-standing challenge. Most proposed measures do not meet the "genuine" requirement, making them unsuitable for many applications. In this work, we propose a journey toward addressing this issue by introducing an unexpected relation between multipartite entanglement and hypervolume of geometric simplices, leading to a tetrahedron measure of quadripartite entanglement. By comparing the entanglement ranking of two highly entangled four-qubit states, we show that the tetrahedron measure relies on the degree of permutation invariance among parties within the quantum system. We demonstrate potential future applications of our measure in the context of quantum information scrambling within many-body systems. [ABSTRACT FROM AUTHOR]

Defining nonlocality in a no‐input closed quantum network scenario is a new area of interest nowadays. Gisin, in [Entropy 21, 325 (2019)], proposed a possible condition for non‐tri‐locality of the trivial no‐input closed network scenario, triangle network, by introducing a new kind of joint measurement bases and a probability bound. In [npj Quantum Information (2020) 6:70] they found a shred of numerical evidence in support of Gisin's probability bound. Now based on that probability bound, it finds the nature of the correlation in a triangle network scenario. This study observes how far the probability lies from that Gisin's bound with every possible combination of entangled and local pure states distributed from three independent quantum sources. Here, it uses the generalized Elegant Joint Measurements bases for each party and find that there is a dependency of non‐locality on the entanglement of these joint measurement bases. It also checks the probability bound for the polygon structure. [ABSTRACT FROM AUTHOR]

Quantum medical image encryption is one of the new methods to send medical images in an insecure communication channel. The proposed method is based on the flexible representation of quantum images which consists of two phases. In the first phase, the medical image is first interlaced using C-NOT gates and then the output of this phase is given to the second phase. In the second phase, one key is defined based on the logical mapping chaos function and the medical image encryption operation is performed based on this key. The output of the second phase is an encrypted image that can only be decrypted by the receiver which has the key. The results of the study of criteria such as histogram, entropy, correlation coefficient of adjacent pixels and correlation diagram show good performance. The entropy value of the proposed method is 99.67 which shows the proposed algorithm has much better performance than previous work. The temporal complexity of the designed quantum circuits is O(n), while the temporal complexity of the previous work is equal to O 2 2 n , which indicates the fast implementation of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We analyze the structure of Feigin-Stoyanovsky's principal subspaces of affine Lie algebra from the jet algebra viewpoint. For type A level one principal subspaces, we show that their shifted multi-graded Hilbert series can be expressed either using the quantum dilogarithm or as certain generating functions "counting" finite-dimensional representations of A -type quivers. This notably results in novel fermionic character formulas for these principal subspaces. Moreover, our result implies that all level one principal subspaces of type A are "classically free" as vertex algebras. We also analyze infinite jet algebras associated to principal subspaces of affine vertex algebras L 1 (so 5) , L 1 (so 8) and L 1 (g 2). We derive a new character formula for the principal subspace of L 1 (so 5) , proving that it is classically free, and present evidence that the principal subspaces of L 1 (so 8) and of L 1 (g 2) are also classically free. [ABSTRACT FROM AUTHOR]

During the COVID pandemic caused by the SARS-CoV-2 virus, studies have shown the efficiency of deactivating this virus via ultraviolet light. The damage mechanism is well understood: UV light disturbs the integrity of the RNA chain at those locations where specific nucleotide neighbors occur. In this contribution, we present a model to address certain gaps in the description of the interaction between UV photons and the RNA sequence for virus inactivation. We begin by exploiting the available information on the pathogen's morphology, physical, and genomic characteristics, enabling us to estimate the average number of UV photons required to photochemically damage the virus's RNA. To generalize our results, we have numerically generated random RNA sequences and checked that the distribution of pairs of nucleotides susceptible of damage for the SARS-CoV-2 is within the expected values for a random-generated RNA chain. After determining the average number of photons reaching the RNA for a preset level of fluence (or photon density), we applied the binomial probability distribution to evaluate the damage of nucleotide pairs in the RNA chain due to UV radiation. Our results describe this interaction in terms of the probability of damaging a single pair of nucleotides, and the number of available photons. The cumulative probability exhibits a steep sigmoidal shape, implying that a relatively small change in the number of affected pairs may trigger the inactivation of the virus. Our light-RNA interaction model quantitatively describes how the fraction of affected pairs of nucleotides in the RNA sequence depends on the probability of damaging a single pair and the number of photons impinging on it. A better understanding of the underlying inactivation mechanism would help in the design of optimum experiments and UV sanitization methods. Although this paper focuses on SARS-CoV-2, these results can be adapted for any other type of pathogen susceptible of UV damage. [ABSTRACT FROM AUTHOR]

The technological advancements made in recent times, particularly in artificial intelligence (AI) and quantum computing, have brought about significant changes in technology. These advancements have profoundly impacted quantum cryptography, a field where AI methodologies hold tremendous potential to enhance the efficiency and robustness of cryptographic systems. However, the emergence of quantum computers has created a new challenge for existing security algorithms, commonly called the 'quantum threat'. Despite these challenges, there are promising avenues for integrating neural network-based AI in cryptography, which has significant implications for future digital security paradigms. This summary highlights the key themes in the intersection of AI and quantum cryptography, including the potential benefits of AI-driven cryptography, the challenges that need to be addressed, and the prospects of this interdisciplinary research area. [ABSTRACT FROM AUTHOR]

Quantum secret sharing plays a crucial role in quantum cryptography. In this paper, we present a rational hierarchical (t,n)-threshold quantum secret sharing scheme based on Lagrange interpolation. In our scheme, participants possess rational and hierarchical properties, and the secret can be reconstructed when the number of rational participants satisfies the hierarchical (t,n)-threshold structure proposed in this paper. The reconstructed secret can encompass both classical information and quantum state information, enhancing the practicality and flexibility of our scheme compared to existing ones. Additionally, we redefine the utility of participants based on their roles in the secret recovery process. This newly defined utility allows for a more precise analysis of the correctness, fairness, and equilibrium of our scheme. Finally, our scheme not only resists a typical set of external attacks but also incorporates mechanisms to detect forgery and collusion among participants. [ABSTRACT FROM AUTHOR]

Proposed by Hillery et al., Quantum Secret Sharing (QSS) is a technique used to break a quantum secret into multiple pieces (called Shares), such that any proper subset of the pieces does not reveal any information about the original secret. The secret can be reconstructed only when all of the pieces are combined together. However, most of the QSS protocols assume that the shares are untampered, hence fail to regenerate the original secret if some of the shares are damaged due to several reasons like cheating participants, eavesdropping, etc. In order to tackle this practical challenge, Resilient Quantum Secret Sharing (RQSS) protocols are required. In this paper, we propose an RQSS protocol that uses Quantum Error Correcting Codes (QECC) for share generation and secret reconstruction. Our protocol generates n shares of a m-qubit quantum secret, owned by the dealer, and distributes it among nparticipants; moreover, it can regenerate the original secret even if k < n shares are damaged. To the best of our knowledge, no such generalized protocol exists in the available literature. [ABSTRACT FROM AUTHOR]

Quantum secret sharing is widely applied in the fields, such as communications and data transmission. In this paper, we propose an authenticable dynamic quantum multi-secret sharing scheme based on the Chinese remainder theorem. In our scheme, the dynamic update of the participants set is permissible without changing the shared secret. To share multi-secret, the distributor generates corresponding shares based on the Chinese remainder theorem and monotone span program, and the GHZ state acts as the information carrier traveling among the participants in the authorization set; the participants utilize the Hadamard operator and Pauli operators to embed their shares in the traveling particles. In this way, the participants will reconstruct multiple secrets. Furthermore, the proposed quantum digital signature algorithm based on entanglement swapping is utilized to realize the identity authentication between participants. The security analysis shows that the proposed scheme can resist intercept-resend attack, entanglement-measurement attack, internal dishonest participant attack, add or withdraw participant attack, and denial attack. [ABSTRACT FROM AUTHOR]

In a secure communication network, multiparty quantum key agreement (MQKA) is crucial for providing multiple participants with secret keys in a fair manner. To address the needs of both multiparty secure communication and point-to-point secure communication simultaneously, this paper introduces a novel two-layer multiparty quantum key agreement (TMQKA) protocol with collective detection, based on non-maximum entangled states. The first-layer agreement key is established among multiple participants to enable secure multiparty communication. The second-layer agreement key is established between any two participants to enable point-to-point secure communication. The generation of two-layer keys improves the efficiency of the protocol. In addition, we demonstrate that the proposed TMQKA protocol satisfies the requirements of correctness, security, and fairness. This paper presents a theoretical exploration of TMQKA, contributing to the expanding body of research on multiparty quantum cryptography. Our work represents an attempt to develop secure communication protocols for practical applications. [ABSTRACT FROM AUTHOR]

The emergence of new complex technologies, such as cloud and quantum computing, has a complicated computational structure, which can compromise the security of traditional cryptographic protocols. It has been noted that traditional security systems utilize non-quantum resistance factorization and Diffie–Hellman (DH) hard problems for their protection. Lattice-based cryptography appears to be a potential post-quantum substitute for the presently employed public-key cryptography. As a result, we have been motivated to focus on increasingly sophisticated and challenging lattice hard assumptions capable of withstanding new modern technologies with quantum resistance properties. In this paper, we devise a new lattice-based public-key encryption and signature schemes with smaller key sizes. The proposed scheme also resists the quantum attack because of the lattice small integer solution problem and its variant. The security claim has also been proved in a well-suited model for quantum attacks. The performance analysis shows that the presented schemes outperform the DH-type schemes and compete with similar lattice-based schemes in terms of storage, communication, key sizes, and computational overheads. [ABSTRACT FROM AUTHOR]

Quantum-key-distribution (QKD) networks are gaining importance and it has become necessary to analyze the most appropriate methods for their long-distance interconnection. In this paper, four different methods of interconnecting remote QKD networks are proposed. The methods are used to link three different QKD testbeds in Europe, located in Berlin, Madrid, and Poznan. Although long-distance QKD links are only emulated, the methods used can serve as a blueprint for the secure interconnection of distant QKD networks in the future. Specifically, the presented approaches combine, in a transparent way, different fiber and satellite physical media, as well as common standards of key delivery interfaces. The testbed interconnections are designed to increase the security by utilizing multipath techniques and multiple hybridizations of QKD and post-quantum cryptography (PQC) algorithms. [ABSTRACT FROM AUTHOR]

Elliptic curve cryptography is a widely deployed technology for securing digital communication. It is the basis of many cryptographic primitives such as key agreement protocols, digital signatures, and zero-knowledge proofs. Fast elliptic curve cryptography relies on heavily optimised modular arithmetic operations, which are often tailored to specific micro-architectures. In this article, we study and evaluate optimisations of the popular elliptic curve Curve25519 for ARM processors. We specifically target the ARM NEON single instruction, multiple data (SIMD) architecture, which is a popular architecture for modern smartphones. We introduce a novel representation for 128-bit NEON SIMD vectors, optimised for SIMD parallelisation, to accelerate elliptic curve operations significantly. Leveraging this representation, we implement an extended twisted Edwards curve Curve25519 back-end within the popular Rust library "curve25519-dalek". We extensively evaluate our implementation across multiple ARM devices using both cryptographic benchmarks and the benchmark suite available for the Signal protocol. Our findings demonstrate a substantial back-end speed-up of at least 20% for ARM NEON, along with a noteworthy speed improvement of at least 15% for benchmarked Signal functions. [ABSTRACT FROM AUTHOR]

Quantum sciences and technologies introduce a new arena whose applications are widely used in the microscopic world. Quantum communication is also an important branch of quantum science by which we intend to transmit quantum information. Quantum teleportation is important because it uses the entanglement principle which is unique in quantum space to transmit quantum information. In fact, in this type of protocol, no information is sent and everything is transmitted using the miracle of entanglement. In this paper, an attempt is made to present a quantum teleportation scheme that, unlike the other designs, can change the destination of qubits. This means that at the beginning of the protocol, the receivers have no idea who has sent the qubits, and the controller decides how these communications will work. At last, noise analysis is presented. [ABSTRACT FROM AUTHOR]

This document is an editorial summarizing the Applied Geometric Algebras in Computer Science and Engineering (AGACSE) conference held in Brno, Czech Republic in September 2021. The conference aimed to promote the use of geometric algebra in fields such as image processing, robotics, and quantum computing. The conference proceedings were published in the journal Mathematical Methods in the Applied Sciences. The editorial provides a list of accepted papers, covering topics such as applied geometry, technological applications, algebra, and quantum phenomena. One specific paper explores the use of geometric algebra in teaching rotations through neural networks. The document is a compilation of research papers showcasing the applications of geometric algebra in various fields, including robotics, control systems, image processing, cryptography, and physics. Each paper presents a specific problem or application and proposes a unique approach or solution using geometric algebra. The authors compare their methods with existing techniques and provide mathematical analysis to support their claims. Overall, the papers demonstrate the versatility and effectiveness of geometric algebra in different domains. [Extracted from the article]

We develop a photonic description of short, one-dimensional electromagnetic pulses, specifically in the language of electrical transmission lines. Current practice in quantum technology, using arbitrary waveform generators, can readily produce very short, few- cycle pulses in a very-low-noise, low-temperature setting. We argue that these systems attain the limit of producing pure coherent quantum states, in which the vacuum has been displaced for a short time, and therefore over a short spatial extent. When the pulse is bipolar, that is, the integrated voltage of the pulse is zero, then the state can be described by the finite displacement of a single mode. Therefore there is a definite mean number of photons, but which have neither a well-defined frequency nor position. Due to the Paley--Wiener theorem, the two-component photon "wavefunction" of this mode, while somewhat localized, is not strictly bounded in space even if the vacuum displacement that defines it is bounded. When the pulse is unipolar, no photonic description is possible--the photon number can be considered to be divergent. We consider properties that photon counters and quantum non-demolition detectors must have to optimally convert and detect the photons in several example pulses. We develop a conceptual test system for implementing short-pulse quantum key distribution, building on the design of a recently achieved Bell's theorem test in a cryogenic microwave setup. [ABSTRACT FROM AUTHOR]

In this paper, we provide a simple approach for determining the rate of secure key production when single-photon and two-photon pulses are used to generate the secure key. For both BB84 and SARG04, we offer estimation and optimization of decoy-state parameters for a single decoy state protocol and two decoy state protocols. This method can be used to determine the lower bound on the fraction of single-photon counts (y1), the fraction of two-photon counts (y2), the upper bound on the QBER of single-photon pulses (e1), the upper bound on the QBER of two-photon pulses (e2), and the lower bound on the key generation rate for both BB84 and SARG04. Due to the limited data size in real-world experiments, we estimate the statistical fluctuations of several parameters, including the gain and QBER of the signal state, as well as the gain and QBER of the decoy state, which are used to estimate the lower bound of key generation rate. We propose formulae that specify the optimal decoy and signal state percentages and intensities. Then we can determine the maximum and optimal key generation rate. For both SARG04 and BB84, we simulated a free space-based QKD system using our decoy state strategy. The simulation results show that free space-based QKD systems that use the suggested approach for BB84 can achieve a higher secret key rate and a greater safe distance than SARG04-based systems. [ABSTRACT FROM AUTHOR]

Quantum cryptography (QC) provides security to information through laws of nature, particularly quantum mechanics. The necessity of making QC a living reality has provided the impetus to advancement in material science, which led to many publications since 1996. Therefore, in this work, we analyze the articles in the Scopus database concerning the contribution of material science in the development of QC through scientometric methods. A total of 1395 articles published from 1996 to 2022 were retrieved from the Scopus database. Subsequently, these articles were analyzed to retrieve publication patterns, major collaborating nations, significant documents, recent trends, and future directions. A comprehensive introduction to QC is also included to facilitate a better grasp of this field for a wide range of readers. The findings of this study show that China is the leading nation in developing QC through material science, closely followed by the United States and India. Moreover, the study indicates significant areas of QC where extensive work is being done from the material science standpoint through keyword and significant document analysis. Hence, the outcomes of this article can be valuable for researchers, newcomers, technology managers, and policymakers interested in the future of QC. [ABSTRACT FROM AUTHOR]

We address the problem of user fast revocation in the lattice-based Ciphertext Policy Attribute-Based Encryption (CP-ABE) by extending the scheme originally introduced by Zhang and Zhang [Zhang J, Zhang Z. A ciphertext policy attribute-based encryption scheme without pairings. In: International Conference on Information Security and Cryptology. Springer; 2011. p. 324–40. doi: https://doi.org/10.1007/978-3-642-34704-7%5f23.]. While a lot of work exists on the construction of revocable schemes for CP-ABE based on pairings, works based on lattices are not so common, and – to the best of our knowledge – we introduce the first server-aided revocation scheme in a lattice-based CP-ABE scheme, hence being embedded in a post-quantum secure environment. In particular, we rely on semi-trusted "mediators" to provide a multi-step decryption capable of handling mediation without re-encryption. We comment on the scheme and its application, and we provide performance experiments on a prototype implementation in the Attribute-Based Encryption spin-off library of Palisade to evaluate the overhead compared with the original scheme. [ABSTRACT FROM AUTHOR]

In the field of post-quantum security, isogeny-based cryptography stands out for its ability to fight quantum attacks. One of the key operations in isogeny-based schemes is finite field multiplication, which plays a crucial role in cryptographic protocols such as key exchange and digital signatures. To ensure practical implementations of these schemes, efficient finite field multiplication is essential. In this research, a novel optimization approach, the Crossover-Boosted Water Cycle Algorithm (CB-WCA), to enhance the efficiency of finite field multiplication in isogeny-based cryptography is proposed. By using both the WCA and a crossover method inspired by genetic algorithms, the CB-WCA effectively explores solution areas, aiming for the best solutions. The formulation of the finite field multiplication optimization problem and an objective function that quantifies the efficiency of the multiplication process based on computational cost is presented and defined. The CB-WCA is then applied to find the optimal set of parameters for finite field multiplication algorithms. Extensive experimental evaluations are conducted, comparing the performance of the CB-WCA-optimized algorithms with traditional optimization methods and other metaheuristic algorithms. Through the findings, it is evident that the CB-WCA stands out for its ability to achieve faster execution times and decrease computational costs. Furthermore, the optimized finite field multiplication algorithms are integrated into isogeny-based cryptographic schemes and evaluate their impact on cryptographic protocol efficiency and security. Real-world implementations showcase the practical applicability of the optimized algorithms in hardware and software environments. To ensure the security of the optimized algorithms, rigorous cryptanalysis is performed to verify their resilience against potential attacks, ensuring they meet the highest standards of security. [ABSTRACT FROM AUTHOR]

Single Photon Sources (SPSs) play a pivotal role in fields such as quantum communication and quantum cryptography by generating information in a secure manner. However, realizing the ideal emission of single photons with high efficiency is still a theoretical model. This leads to the presence of multiphoton components in SPSs, which could potentially compromise security. This study focuses on enhancing the purity of a class of sources by characterizing their photon number distribution and mitigating the impact of the multiphoton components. We propose the use of Photon Number Resolving Detectors (PNRD) as a technique to exclude multiphoton contributions, particularly in sources like Spontaneous Parametric Down Conversion sources, where emitted photons can be represented as Two-Mode Squeezed Vacuum states. By analyzing the second-order cross-correlation function, g2(0), using either PNRD or Single Photon Detectors, we can quantify the reduction in multiphoton contributions. [ABSTRACT FROM AUTHOR]

Quantum secure multi-party summation (QSMS) is a fundamental problem in quantum secure multi-party computation (QSMC), wherein multiple parties compute the sum of their data without revealing them. This paper proposes a novel QSMS protocol based on graph state, which offers enhanced security, usability, and flexibility compared to existing methods. The protocol leverages the structural advantages of graph state and employs random graph state structures and random encryption gate operations to provide stronger security. Additionally, the stabilizer of the graph state is utilized to detect eavesdroppers and channel noise without the need for decoy bits. The protocol allows for the arbitrary addition and deletion of participants, enabling greater flexibility. Experimental verification is conducted to demonstrate the security, effectiveness, and practicality of the proposed protocols. The correctness and security of the protocols are formally proven. The QSMS method based on graph state introduces new opportunities for QSMC. It highlights the potential of leveraging quantum graph state technology to securely and efficiently solve various multi-party computation problems. [ABSTRACT FROM AUTHOR]

An effective post-processing algorithm is essential for achieving high rates of secret key generation in quantum key distribution. This work introduces an approach to quantum key distribution post-processing by integrating the three main steps into a unified procedure: syndrome-based error estimation, rate-adaptive reconciliation, and subblock confirmation. The proposed scheme employs low-density parity-check codes to estimate the quantum bit error rate using the syndrome information, and to optimize the channel coding rates based on the Slepian–Wolf coding scheme for the rate-adaptive method. Additionally, this scheme incorporates polynomial-based hash verification in the subblock confirmation process. The numerical results show that the syndrome-based estimation significantly enhances the accuracy and consistency of the estimated quantum bit error rate, enabling effective code rate optimization for rate-adaptive reconciliation. The unified approach, which integrates rate-adaptive reconciliation with syndrome-based estimation and subblock confirmation, exhibits superior efficiency, minimizes practical information leakage, reduces communication rounds, and guarantees convergence to the identical key. Furthermore, the simulations indicate that the secret key throughput of this approach achieves the theoretical limit in the context of a BB84 quantum key distribution system. [ABSTRACT FROM AUTHOR]

Semi-quantum signature is an important research topic in quantum cryptography. Based on the Bell states, a semi-quantum signature scheme with arbitrator is proposed. In our scheme, the quantum signer signs the message by encoding the ciphtext with the Bell states and performing the controlled NOT gate on the particles, while the signature receiver and arbitrator corporately verify the signature by measuring the received qubits with Z-basis. Compared with the similar schemes, ours has the better performances as follows. (1) It can be proved to be information-theoretically secure. It has the strong undeniability property. (2) The signer is a quantum partner, while both the signature receiver and the arbitrator are classical partners. (3) The signer needn't share any private key with the receiver. (4) The scheme is based on Bell state, which is relatively easier to be prepared than the other entanglement resources used in the similar schemes. (5) It has better qubit efficiency. Therefore, our scheme has better performances in security, practicability and efficiency than the similar schemes. [ABSTRACT FROM AUTHOR]

Perfect state transfer has attracted much interest recently due to its significant applications in quantum information processing and cryptography. In this paper, we investigate perfect state transfer on Cayley graphs over dicyclic groups. Utilizing the representations and characters of dicyclic groups $ T_{4n} $ T 4 n , some necessary and sufficient conditions for Cayley graphs over dicyclic groups admitting perfect state transfer are provided. By those results, some concrete constructions are presented. [ABSTRACT FROM AUTHOR]

This article describes the author's experience designing and implementing an inquiry-based learning (IBL) pedagogical approach to an upper-division undergraduate cryptology course. The author shares the course goals and how the IBL style supports their achievement. The article concludes with sample activities – in-class exercises that touch on one-time pad, the Birthday Problem, the Meet-in-the-Middle attack, and Diffie–Hellman key exchange protocol, and a programing assignment on the Vigenère cipher. [ABSTRACT FROM AUTHOR]