Atoms and photons, two things so different but yet so alike. The former, the building block of matter, something we learn about in school and imagine it as some tiny marbles encircled by other tinier marbles. The latter, an electromagnetic wave, a light particle or an excitation of the electromagnetic field. Quantum mechanics tells us about the properties of these two entities. And even if it sounds, looks and writes counter-intuitive, it has proven right for over a century now. In this work, I elaborate on how we tested the laws of quantum mechanics and how we used them learn more about the tiny building blocks of nature and the fields they use to talk to each other. The atoms we use, are artificial. Superconducting qubits, small electrical circuits with quantized energy levels behave like electrons that transition between different orbitals in an atom. One of the qubits' advantages, is also a big disadvantage. We design the circuits' energy levels and fabricate them in a cleanroom. This allows for arbitrary spaced energy levels but in contrast to real atoms, prevents two superconducting qubits from being alike. Still, this qubit platform is one of the frontrunners for future quantum computing technology and testing fundamental physics due to their scalability. We interface superconducting qubits, which operate in the GHz regime, with microwave photons. We use 3D aluminum cavities as mediators between qubits and photons. The cavities allow for non-destructive readout of the qubit state, they shield the qubits from noise at the qubit frequency and they give us an easy way to frequency-tune these joint systems. We need to operate superconducting qubits and their cavities at millikelvin temperatures in dilution refrigerators. At higher temperatures, superconductivity suffers and even worse, the environment is filled with thermal noise photons. This poses a fundamental limitation on the scalability of superconducting qubit devices. Also connecting multiple devices in different fridges does not work over room temperature links because the microwave photons used for this purpose will be covered in noise and the quantum information they carry, will be unusable. Infrared photons do not suffer from this noise problem since there are close to zero thermal noise photons at their frequencies at room temperature. We cannot simply interface superconducting devices with optical photons due their frequency mismatch and the destructive effect of optical photons on superconductors. Therefore, we use microwave-to-optics transducers that allow to convert microwave photons into optical ones and vice-versa. The transducers that we use are macroscopic electro-optic transducers using the Pockels effect in a disk-shaped Lithium Niobate whispering gallery mode resonator. By using a strong optical pump, photons from the two frequency domains experience a beam-splitter interaction and get converted from one to the other. We measure the generated optical photons using elaborate optical setups, optical heterodyning and single photon detectors to gain knowledge about the qubit state or the converted microwave photons. Bridging the microwave and the optical world allows us to take advantage of both of their strengths but it also requires deep knowledge about both of their working principles. In this work, we describe two experiments that our group conducted to showcase the opportunities that arise from interfacing superconducting qubits with optical photons but also the pitfalls, one may encounter on the way. In the first experiment, we managed to all-optically read out a superconducting qubit. We show that the assignment fidelity, the probability that a measurement of the qubit state matches the prepared state, is close to equal for all-optical, microwave-to-optics and conventional microwave readout. We show T1 and T2 measurements for all three readout types and give an analysis of the noise caused by the optics. Finally, we show that the infrared light does not affect the qubit performance in a negative way but that the heating it causes does. This is an important insight that we used in the next experiment. The second experiment is the upconversion of itinerant single microwave photons to the optical domain. We show that we can generate single microwave photons from a qubit-cavity system. We upconvert these single photons, measure them with a single photon detector and reconstruct their shape. By conducting a single photon Rabi measurement, we show correlations between the microwave and the optical domain. And by thorough signal-to-noise measurements and noise analysis, we find that we can generate single infrared photons with high signal-to-noise ratio 5.1 and low transducer added noise (<0.012 quanta). We show that this measurement creates a path towards entanglement of a superconducting qubit and an optical photon and what parameters need to be improved to achieve it. Additionally, this experiment is a proof of principle for an on-demand infrared single photon source. More generally, it allows to link microwave quantum technology in general to the optical domain.
João Pires da Cruz, Daniel Costa, Armando Teixeira, João B. Duarte · 6 authors
We analyze the Ethereum transaction network using a spectral decomposition based on functional edge modes. Each transaction is represented as a complex amplitude indexed by the combined connectivity of the interacting addresses, and amplitudes are aggregated into mode-resolved coherent sums. Applying this construction to a snapshot of native ETH transfers from the second half of 2015 (âŒ1.9 Ă 10 6 transactions across 26,937 addresses), we identify spectral modes whose coherent power significantly exceeds that obtained under randomized phase baselines. Statistical significance is assessed via B = 1000 phase permutations with multiple-testing correction: 469 of 928 modes (50.5%) survive Benjamini-Hochberg control at the 5% false discovery rate, while none survive the more conservative Bonferroni threshold. Strong global coherence is primarily driven by high-degree nodes: removing the top 0.1% of nodes by degree (27 hubs) collapses the bulk of the spectrum towards the randomized baseline. However, statistically significant residual coherence persists across roughly half of the tested modes, indicating that organization in the network is not purely an artifact of hub aggregation. We frame these findings through a quantum-like analogy in which phase-aligned edge contributions interfere constructively, and discuss implications for the structural analysis of decentralized financial systems.
Dr. Megala Rajendran, R. Gopalakrishnan, Dr.A. Dharmaraj, Dadajon Dadabayev Rustamovich
Background: Quantum computing poses a threat to classical signatures, like ECDSA, and makes long-lived blockchain smart contracts, particularly those used in a system of the circular economy and sustainability, susceptible to future forgery and governance attacks. Abstract: This paper presents a quantum resilient smart contract lattice architecture to achieve ethical governance and resource tracking in the use of a circular economy and maintain realistic performance. Methods: The architecture uses a NISTâtrack latticeâbased postâquantum signature scheme (CRYSTALSâDilithium) with one signature per transaction in an Ethereumâlike environment, adds batched postâquantum verification opcodes to the virtual machine and a postâquantumâaware gas model, and introduces Solidity contracts for recycle passports, tokenized wasteâmanagement incentives, and DAOâbased governance. Ethical governance is operationalized using a transparency index together with quantitative fairness and inclusiveness measures derived from reward distributions and participation rates. Results: The proposed framework has a 2.0 ms verification latency, 450 transactions per block, 70% relative throughput, and 130 GB/year storage, compared to 2.8 ms verification, 268 transactions per block, 55% relative throughput, and 140 GB/year storage in the hybrid postâquantum baseline and the classical ECDSA configuration. Conclusion: These findings suggest quantum resilient smart contracts are a promising basis of long-horizon circular economy governance, which provides superior security and ethics by design assurances and sustains competitive performance and sustainability attributes compared to both classical and hybrid post-quantum baselines.
Temporal-Angular Quantum Addressing (TAQA) specifies a practical coordination layer for distributed quantum systems that operationalizes cycle-anchored phase-window execution. TAQA is designed for architectures where long-horizon absolute timestamp synchronization cannot be guaranteed and where continuous external timing infrastructure (GNSS, dedicated timing links, etc.) is undesirable, unavailable, or untrusted. Core idea Instead of scheduling actions at an absolute time, TAQA schedules actions by phase conditions on a shared cyclic phase convention \( \phi(t)\in[0,1)\cong \mathbb{S}^1 \) together with an explicit cycle index. Nodes execute when their locally estimated phase enters an agreed wrap-around-safe acceptance window within the intended cycle. This avoids âsame phase / wrong cycleâ ambiguity and supports deterministic coordination under explicit short-horizon error assumptions. What TAQA defines TAQA defines how to express and execute distributed quantum-network actions using classical metadata: Execution primitive (Q-Address style): TAQA expresses each executable action as a macro window + micro slot instruction. The macro window encodes the intended cycle and phase acceptance window; the micro slot provides local sequencing/offset ordering within that window using local hardware timing. Tick-canonical semantics: For interoperability and verification, TAQA adopts fixed-point ticks (integers) as canonical semantics (no floating-point boundary checks). Human-facing displays (HS degrees, HS index, SWT labels, etc.) are derived-only and must not be used for verification or boundary gating. Cycle anchoring: Every executable instruction is explicitly anchored to an intended cycle index to prevent ambiguous interpretation across repeated cycles. Optional audit hook: TAQA supports an optional post-execution signed audit receipt (TSAE-style) using the same tick-canonical context fields, suitable for optional anchoring (e.g., a ledger/Clockchain pattern). What TAQA does NOT define TAQA is a control-plane / metadata layer and does not modify quantum mechanics: It does not introduce a quantum time operator and does not change the Hilbert space. It does not define bootstrapping or clock-parameter estimation algorithms (offset/drift). These are handled by external initialization/tracking layers (e.g., bootstrapping protocols). It does not define cryptographic primitives or threat models. Security is defined by external, versioned security profiles. Applications enabled by TAQA TAQA provides a deterministic coordination layer for common distributed-quantum workflows, including: Phase-aligned distributed gate execution: remote node actions are triggered in the same cycle-anchored window; micro timing is local. Entanglement distribution scheduling: photon emission windows and BSM windows can be scheduled to coincide without continuous absolute-time synchronization. Temporal routing labels: cycle-anchored contexts can be used as temporal labels for routing, prioritization, and scheduling in repeater networks and distributed workflows. Security model (plug-in interface) TAQA treats Timeverse/Q-Address/TSAE fields as public context (not secrets). Security (signatures, nonce policy, anti-replay rules, canonical encoding, algorithm suites) is provided by an external Security Profile selected via a suite identifier (e.g., security_profile_id). TAQA fields may be bound as associated data (domain separation), but confidentiality and integrity are provided by the security layer. Normative dependencies (DOIs) TAQA is interoperable by construction and relies on the following published normative specifications: Phase-Coordination Series Conventions:https://doi.org/10.5281/zenodo.18068999 Q-Address: Macro Phase + Micro Slot:https://doi.org/10.5281/zenodo.18068997 Timeverse Security Profile:https://doi.org/10.5281/zenodo.18069423 Related context Theorem of Temporal Resolution Limitation and the Phase-Coordination Principle (v1.1):https://doi.org/10.5281/zenodo.17955430 Quantum Bootstrapping Protocol (QBP) v1.2:https://doi.org/10.5281/zenodo.18064435 Keywords: TAQA, distributed quantum computing, quantum networks, phase coordination, phase windows, cycle anchoring, Q-Address, ticks, interoperability, control plane, audit receipts, security profiles.
Khang Wen Goh, Burhan Ul Islam Khan, Abdul Raouf Khan, Dwi Sudarno Putra · 6 authors
Blockchain systems built on classical cryptography face immediate risks from large-scale quantum computers, while purely quantum-based blockchains often rely on a single Private Key Generator (PKG) and incur heavy resource overheads. To overcome these issues, this paper proposes a hybrid quantum and post-quantum blockchain approach that removes single points of trust by using Distributed Key Generation and a dual-layer signature mechanism. This method integrates quantum digital signatures, rooted in the Fully Flipped Permutation problem, with classical post-quantum (lattice-based) cryptography, enabling users to switch between quantum and classical signatures according to security requirements and channel conditions. Delegated Proof-of-Stake with node behavior and Borda count has been incorporated to manage consensus, ensuring that witness nodes are regularly re-elected and malicious actors are penalized by distributing secret shares among multiple rotating witnesses. We eliminate the central vulnerability of a sole PKG while maintaining rigorous resistance to collusions. Our analytical model indicates that a fraction of transactions can use quantum signatures without system-wide bottlenecks, while the remaining transactions follow classical PQC paths with throughput approaching classical baselines under our modeling assumptions. Consequently, this hybrid method offers higher scalability, robust collusion resistance, and long-term security even under quantum-capable adversaries. This paper presents extensive theoretical analyses, probability models, and algorithmic complexities, demonstrating that our design provides resilient infrastructure that meets the key performance and security requirements of next-generation blockchain systems.
Secure interoperability across heterogeneous blockchains remains one of the most pressing challenges in Web3 with existing bridge protocols vulnerable to both classical exploits and emerging quantum threats. This paper introduces QLink a quantum-safe Layer 3 interoperability protocol that integrates postquantum cryptography (PQC) quantum key distribution (QKD) and hardware security modules (HSMs) into a unified validator architecture. To our knowledge, QLink is the first interoperability framework to combine these mechanisms to secure validator communication proof aggregation and key management. Validators exchange encryption keys through QKD channels, achieving information-theoretic security against interception, while cross-chain proofs are generated and aggregated with NIST-standardized PQC algorithms. Private keys remain sealed inside HSM enclaves mitigating the risk of theft or leakage. Deployed as a dedicated Layer 3 protocol QLink operates independently of Layer 1 and Layer 2 chains providing a scalable decentralized foundation for secure cross-chain messaging and asset transfer. Experimental evaluation using network simulations demonstrates that validator communication overhead remains sub-second while security guarantees extend beyond current bridge architectures to resist both classical and quantum adversaries. By addressing today vulnerabilities and anticipating future quantum threats QLink establishes a practical and future-proof pathway for blockchain interoperability.
P. Jeba Santhiya, Fackrudeen Ali Ahamed, Absalamova Gulmira Sharifovna, Christo Ananth · 6 authors
AQBCP is an Adaptive Quantum Byzantine Consensus Protocol that allows for trustless, scalable consensus in post-classical quantum blockchain systems. AQBCP has the capability of using hybrid quantum/classical methods (including dynamic pruning and quantum routing) to improve the reliability of its network and also improve how well it performs. AQBCP will have more than 50% BFT - which is greater than most classical algorithms - and can adapt to any changes in the network topological structure or the conditions of the quantum channels it uses. The analytical and simulation data shows AQBCP converges at a rate of O(log(n)), provides information theoretic security from classical and quantum enabled attacks and has better performance metrics for throughput and fault tolerance when run on current NISQ devices. The benchmarking of AQBCP with other post-quantum and quantum-classical protocols provides evidence that AQBCP is the best option and sets a base for future quantum secure distributed ledgers.
We study non-interactive zero-knowledge proofs (NIZKs) for NP satisfying: 1) statistical soundness, 2) computational zero-knowledge and 3) certified-everlasting zero-knowledge (CE-ZK). The CE-ZK property allows a verifier of a quantum proof to revoke the proof in a way that can be checked (certified) by the prover. Conditioned on successful certification, the verifier's state can be efficiently simulated with only the statement, in a statistically indistinguishable way. Our contributions regarding these certified-everlasting NIZKs (CE-NIZKs) are as follows: - We identify a barrier to obtaining CE-NIZKs in the CRS model via generalizations of known interactive zero-knowledge proofs that satisfy CE-ZK. - We circumvent this by constructing CE-NIZK from black-box use of NIZK for NP satisfying certain properties, along with OWFs. As a result, we obtain CE-NIZKs for NP in the CRS model, based on polynomial hardness of the learning with errors (LWE) assumption. - In addition, we observe that the aforementioned barrier does not apply to the shared EPR model. We leverage this fact to construct a CE-NIZK for NP in this model based on any statistical binding hidden-bits generator, which can be based on LWE. The only quantum computation in this protocol involves single-qubit measurements of the shared EPR pairs.
This is the fourth and most comprehensive edition of the theoretical framework introduced in the original preprint (DOI: 10.5281/zenodo.17834958). The Universal Distributed Architecture (UDA) proposes a three-dimensional quantum blockchain of Planck-scale quantum cubes governed by a novel Proof-of-Consciousness (PoC) consensus protocol. Five core equations are rigorously derived and proven: the PoC consensus operator (Kraus representation), the Absolute validator state, ledger entropy growth rate (Lindblad form), OAM entanglement threshold, and quantum-resistant hash function. The work integrates loop quantum gravity, AdS/CFT correspondence, the Sachdev-Ye-Kitaev (SYK) model, JT gravity, and holographic tensor networks (MERA, PEPS, and 5D extensions), together with five-dimensional optical memory crystals (University of Southampton) as an experimental substrate, with equations 27â34 establishing Rayleigh scattering as a physical implementation of holographic hash verification and a room-temperature experimental protocol. Version 4 introduces three structural advances. (1) A ledger isomorphism (Proposition 0): every axiom of a distributed append-only ledger â immutability, decentralized consensus, append-only ordering, bounded block capacity, and double-spend prohibition â is shown to be independently realized by an established physical principle (no-cloning/no-deleting theorems, quantum Darwinism, the second law, the BekensteinâBousso bound, and monogamy of entanglement), localizing UDA's novel content entirely in the validation rule. (2) An operational, laboratory-reproducible definition of the consciousness quantity, |Q| = m/m_P = Ï_C·t_P, integrating Inomata's pan-psychist quantity Q = iâG·M and measurable through three independent channels: Compton-clock interferometry and gravitationally induced entanglement (BMV), a standardized measurement-induced-phase-transition (Q-MIPT) meter on quantum processors with explicit calibration and uncertainty budget, and collider bounds on event-driven non-unitarity anchored by ATLAS/CMS top-quark entanglement and neutral-kaon CPT interferometry. The channel-universality law Q_G = Q_I = Q_C is the flagship prediction exclusive to UDA. (3) A sharp mathematical distinction between the anti-Hermitian consciousness operator (magnitude of agency: write capacity per Planck tick) and the Hermitian moral operator (valence of agency: mutual-information gain per unit entropy budget), with an explicit laboratory protocol distinguishing them. The framework further develops a SYKâConsciousness correspondence with non-Hermitian topological phases, MIPT modulated by consciousness density, and non-Hermitian MERA networks exhibiting a Holographic Skin Effect that topologically protects conscious information at the holographic boundary. UDA's non-unitarity is event-driven rather than continuous, making it consistent by construction with DiĂłsiâPenrose bounds and separable from collapse models in a single two-parameter experiment (Discriminator D1). Falsifiable predictions are organized in two tiers â five UDA-exclusive predictions (2026â2030), each with its own falsification clause, and inherited consistency tests â alongside detailed QuTiP simulations, NV-center and 5D crystal protocols, and applications in quantum computing, quantum AI, and high-energy tests at the LHC and FCC. The framework resolves the von Neumann measurement chain via dual observation and portrays the universe as a growing, error-corrected quantum ledger.
I formalize the Arquitectura Universal Distribuida (AUD) as a three-dimensional quantum blockchain of Planck-scale âquantum cubesâ governed by the novel Proof-of-Consciousness (PoC) consensus protocol. Each cube acts as a Loop Quantum Gravity spin-network node and full validator. Information is stored holographically via universal entanglement, providing a provably unclonable hash function. The global validator â the Absolute â enforces non-local consensus through Bell-inequality violations and high-energy entanglement observed at the LHC. The model resolves the von Neumann measurement chain and predicts observable deviations in entanglement entropy growth.
On-demand authentication is critical for scalable quantum systems, yet many existing quantum signature and message-authentication schemes are signer-initiated, requiring advance distribution of authentication material even when no verification occurs. We introduce verifier-initiated quantum digital signatures (VIQDS), in which the verifier requests authentication only when needed and the signer responds once; after issuance, verification proceeds without further interaction. Practically, shifting authentication to a verifier-driven, on-demand workflow reduces avoidable communication and storage overhead and aligns with deployments where verification is sporadic, such as distributed services and audit-oriented infrastructures. Our approach leverages quantum zero-knowledge techniques so that verification reveals nothing about the signerâs secret key beyond the fact that the signature is valid. We present a general conversion principle from suitable quantum proof protocols to VIQDS, together with a concrete realization based on elementary qubit platforms. Here, we show information-theoretic security against forgery and privacy against curious verifiers without computational hardness assumptions. The authors introduce a verifier-initiated quantum message-authentication method, in which authentication is requested only when needed. Their approach uses quantum zero knowledge techniques to protect information about the signerâs secret key while providing information-theoretic security against forgery
The arrival of quantum computing poses a huge threat to conventional public key cryptography used in blockchain systems such as Bitcoin. To address this challenge, we proposes and evaluates a quantum resistant sidechain framework that integrates post quantum digital signature schemes and quantum key distribution (QKD) protocols with the Bitcoin mainchain. Using a Python simulation environment, the performance of multiple signature algorithms. ECDSA as a baseline measurement, Falcon, CRYSTALS-Dilithium, and SPHINCS+ were analyzed in combination with quantum communication protocols BB84, E91, and SARG04. Experimental results show that ECDSA remains the fastest baseline scheme but lacks quantum resistance, while SPHINCS+ provides the highest security with an expected overhead of 93.5 %. Among quantum protocols, BB84 achieved the best overall efficiency across transaction sizes. The optimal integration pairs were BB84 and CRYSTALS-Dilithium combination for speed, security balance and SPHINCS+ and E91 for maximum quantum resilience. These findings demonstrate the practical feasibility of deploying post quantum cryptographic components in Bitcoin compatible sidechains, paving the way for future blockchain networks that remain secure in the post quantum era.
Blockchain technology has emerged as the backbone of cryptocurrencies and decentralized finance, yet its long-term resilience is increasingly threatened by advances in quantum computing. Quantum algorithms, such as Shorâs algorithm, can undermine public-key cryptography, while Groverâs algorithm accelerates brute-force search, weakening proof-of-work schemes. In this paper, we propose a Quantum Blockchain Framework that integrates quantum communication protocols, quantum consensus mechanisms, and quantum-resistant cryptography. We construct a theoretical model of quantum-secured distributed ledgers, where qubits, entanglement, and quantum key distribution (QKD) enhance security and efficiency. Applications to cryptocurrency are explored, highlighting how quantum blockchain can mitigate security risks, improve consensus speed, and enable quantum-native digital assets.
This paper presents a comparative analysis of three cryptographic approaches to securing fiber-optic data transmission: classical RSA/AES, Quantum Key Distribution (QKD) based on the E91 protocol, and Secure Dynamic Stream Encryption (SDSE). These are evaluated in terms of latency, key renewal frequency, computational load, energy efficiency, and resilience to quantum attacks. In addition to these core comparisons, we extend SDSE with a blockchain-based governance layer. This enhancement introduces auditable key management through distributed ledger technology (DLT), ensuring transparent tracking of key rotations, revocations, and policy enforcement without storing any secret material. The blockchain acts as a trust anchor for multi-node synchronization, particularly useful in federated or multi-domain environments. The combined SDSE + Blockchain framework provides a lightweight, quantum-resilient, and scalable encryption mechanism suitable for real-world deployment across conventional optical infrastructure.
The transition to post-quantum cryptography poses an unprecedented challenge for Bitcoin and Ethereum, as it involves implementing a defensive downgrade that imposes immediate, severe costs with no tangible benefits. While quantum computers capable of breaking secp256k1 require between 523â2,500 logical qubits, with the author deriving 523 logical qubits as an algorithmic lower bound (not inclusive of arithmetic and ancilla qubits) for a canonical Shor/phase-estimation circuit using the formula QL = 2âlog2(n)â + 2 + âlog2(2 + 1/(2Δ))â for Δ = 0.001, and conservative estimates ranging up to 2,500 logical qubits based on comprehensive resource modelsâsignificantly less than the 2,100â2,400 logical qubits es- timated for general elliptic curvesâcurrent systems achieve only âŒ100 logical qubits. IBMâs quantum roadmap projects 500â1,000 logical qubits by 2029, placing the critical threshold within 4â10 years depending on which estimate proves accurate. This timeline collides with the reality that convincing decentralized communities to accept 50% capacity loss and 2â 3Ă fee increases may take 10â15 years in themselves, based on historical governance patterns where even beneficial upgrades required 2â5+ years. Current testnet implementations on per- missioned systems show measurable performance degradation. Critically, this data comes from fundamentally different architectures than permissionless networks, which will likely experience 30â50% additional performance degradation due to global verification requirements, heterogeneous hardware, and compounding propagation delays. This methodological limitationâextrapolating from permissioned to permissionless systemsârepresents a critical infrastructure failure that introduces massive uncertainty into migration planning. Com- pounding this challenge, secp256k1 is not officially approved by NIST under FIPS 186-5 or SP 800-186, creating additional regulatory vulnerabilities. Beyond transient impacts, PQC creates permanent state bloat, with quantum-resistant accounts requiring 59 times more storage (1,952 bytes / 33 bytes = 59.2Ă for ML-DSA-65), thereby accelerating centralization- tion. This paper presents a comprehensive framework acknowledging these harsh realities. While we propose specific BIP/EIP implementations and optimization strategies that might achieve 50â60% capacity retention, we recognize that the quantum threat timeline may now be shorter than even the minimum viable migration period. Unlike beneficial upgrades like SegWit (which took 20 months for activation and 5+ years for 50% adoption despite offering improvements), PQC migration is a purely defensive measure imposing only costs. The stark reality: blockchain communities must choose between accepting immediate emergency action or facing quantum vulnerability by 2029.
Jamil Abedalrahim Jamil Alsayaydeh, Mohd Faizal Yusof, Nor Adnan Yahaya, Viacheslav Kovtun · 5 authors
In today's digital world, cryptocurrencies like Bitcoin can secure transactions without banks. However, the rise of quantum computing poses significant threats to their security, as traditional cryptographic methods may be easily compromised. In addition, the existing algorithms face difficulties like slow transaction speeds, interoperability issues between different cryptocurrencies, and privacy concerns. Hence, Quantum Crypto Guard for Secure Transactions (QCG-ST), a novel blockchain framework, is introduced, offering enhanced security and efficiency for cryptocurrency transactions. The QCG-ST employs lattice-based cryptography to provide robust protection against quantum threats and incorporates a new consensus mechanism to increase the transaction speed and reduce energy consumption. The QCG-ST system uses lattice-based encryption that is based on the Ring Learning With Errors (Ring-LWE) issue to protect itself from quantum assaults. It uses sharding, a Proof-of-Stake (PoS) consensus method, and a threshold signature scheme (TSS) to make the system more scalable and use less energy. Zero-knowledge proofs (ZKPs) are used to check transactions without giving out private information. We offer a cross-chain atomic swap protocol that uses hashed time-lock contracts to make sure that it works on all platforms. Blockchain transaction data utilized in testing originated from the Bitcoin Historical Dataset available on Kaggle, and quantum resistance has been assessed using the Qiskit Aer simulator. It evaluated the framework's performance to that of traditional methods like Payment Channel-Lightning Network (PC-LN), Variational Quantum Eigensolver (VQE), and Cross-Chain Transaction with Hyperledger (CCT-H). Results show that QCG-ST does far better than traditional systems in terms of transaction success rate (up to 98.5%), speed, energy efficiency, latency, and throughput, especially when tested in a quantum-simulated environment. This study completes in an essential vacuum in blockchain technology by suggesting a strong, quantum-resistant, privacy-protecting architecture that can handle the problems that could arise up in decentralized digital banking in the future.
Quantum computing stands poised to transform numerous fields of modern technology by offering computational capabilities beyond those of classical systems. This survey offers a detailed analysis of major fields, such as artificial intelligence and machine learning (AI/ML), blockchain, cybersecurity, and digital communication, highlighting how they are significantly transformed through advancements in quantum computing. It presents a comparative analysis of current quantum computing paradigms and architectures, and examines major quantum algorithms such as Shorâs integer factorization algorithm, Groverâs search algorithm, and hybrid quantumâclassical approaches like QAOA and VQE, highlighting their implications for real-world problem solving. Significant advancements in quantum hardware are surveyed, from increasing qubit counts and improved coherence to progress in error mitigation and emerging quantum processor technologies, and their impact on near-term and long-term computing capabilities is evaluated. Finally, the current limitations of quantum computing are discussed, and forward-looking insights into future research directions are provided, outlining the path toward fully harnessing quantum power across industries.
Abstract Oblivious transfer is a type of message transfer in which a sender transmits one out of many potential pieces of information to the receiver, but she has no knowledge about the actual piece of information being received by the receiver. Oblivious transfer is a deceptively simple scheme that has many possible applications such as secure multiparty computation, private set intersection, federated learning, zero-knowledge proofs, accessing sensitive data etc. Security of most classical oblivious transfer protocols is based upon the unproven assumptions about the computational complexity of certain number theoretic problems such as integer factorization. So, existing classical protocols for oblivious transfer are only computationally secure and not unconditionally secure. Although many quantum oblivious protocols have been proposed lately, they are not simple and easy to implement. In the present work we propose a quantum oblivious transfer protocol that is efficient, simple and easily implementable with the existing quantum technology.
Federated Learning (FL) has become increasingly popular across different sectors, offering a way for clients to work together to train a global model without sharing sensitive data. It involves multiple rounds of communication between the global model and participating clients, which introduces several challenges like high communication costs, heterogeneous client data, prolonged processing times, and increased vulnerability to privacy threats. In recent years, the convergence of federated learning and parameterized quantum circuits has sparked significant research interest, with promising implications for fields such as healthcare and finance. By enabling decentralized training of quantum models, it allows clients or institutions to collaboratively enhance model performance and outcomes while preserving data privacy. Recognizing that Fisher information can quantify the amount of information that a quantum state carries under parameter changes, thereby providing insight into its geometric and statistical properties. We intend to leverage this property to address the aforementioned challenges. In this work, we propose a Quantum Federated Learning (QFL) algorithm that makes use of the Fisher information computed on local client models, with data distributed across heterogeneous partitions. This approach identifies the critical parameters that significantly influence the quantum model's performance, ensuring they are preserved during the aggregation process. Our research assessed the effectiveness and feasibility of QFL by comparing its performance against other variants, and exploring the benefits of incorporating Fisher information in QFL settings. Experimental results on ADNI and MNIST datasets demonstrate the effectiveness of our approach in achieving better performance and robustness against the quantum federated averaging method.
Collins Izuchukwu Okafor, Love Allen Chijioke Ahakonye, Jae Min Lee, DongâSeong Kim
Integrating Internet of Things (IoT) networks with blockchain technology has introduced transformative potential for secure, decentralized applications. However, with expanding IoT networks and the rapid advancements in quantum computing, which can break the classical encryption mechanism employed in these networks, securing validator communications in blockchain consensus mechanisms becomes increasingly challenging. This study presents PureQuantum, a novel quantum-enhanced framework that integrates quantum key distribution (QKD) into a proof-of-authority and association (PoA 2 ) consensus mechanism. Our experimental evaluation demonstrates that PureQuantum achieves a key generation time of approximately 2.315 s (BB84) and an average error rate of 0.2493, thereby ensuring robust resistance to classical and quantum computational threats. Exploring the architecture, design, and performance of PureQuantum, this concept highlights its ability to balance scalability, energy efficiency, and quantum-resilient security. By integrating QKD into validator communication protocols, PureQuantum provides a future-proof framework capable of supporting the demands of IoT-enabled decentralized systems.