Quantum Information Processing最新文献

The transfer of a quantum state without the physical movement of the particles directly is one of the main jobs in the field of quantum communication technology. In this manuscript, we prepare a multi-tasking protocol in which the main objective is to create an interconnecting quantum network between three quantum communication protocols such as quantum teleportation, remote state preparation and joint remote state preparation by use of a single quantum network. For this purpose, an 8-qubit entangled state is used as a communication channel amongst the parties. The quantum circuit for the preparation of the entangled channel is given in the protocol. Further we have performed the analysis of the effect of environmental noise on our protocol. The protocol is executed on the IBM platform.

Conventional digital signature and authentication systems lack security and are unable to identify possible risks from quantum computing or eavesdropping. Therefore, the scheme is designed and innovative in that, first, a quantum man-in-the-middle attack (QMITM) threat model is constructed, which analyzes and improves the security threats that may be triggered by quantum attackers in order to ensure the reliability of signatures during authentication and transmission. Secondly, in the phase of quantum identity authentication, an encryption method based on quantum gate transformation is proposed and implemented. The algorithm is used in the quantum identity authentication process. In addition, in order to provide security and resist quantum attacks in the signature phase, quantum signature technology based on unitary operation is adopted. Finally, in the security analysis, its security based on quantum key distribution protocol (QKDP) is supported by formal proof, which meets the requirements of unfalsifiability, non-repudiation and better qubit efficiency.

Quantum computing trained for the future requires robust, fault-tolerant infrastructure to realize transformative computational capacities. Accomplishing this necessitates millions of qubits, high-fidelity quantum gates, and resilient systems for error correction and feasible runtime. Neutral-atom qubits, controlled by lasers in closely narrowed optical arrays, have surfaced as an appealing platform for adaptability and accuracy. Conventional approaches depend upon real-world mid-circuit qubit shuttling, which limits computing velocity. This study introduces FRQC (Future-Ready Quantum Computing), evaluated through Python Quantum Simulation (Qiskit), an innovative infrastructure that combines neutral atoms with dynamic optical signaling to provide rapid, fault-tolerant computations. Utilizing configurable laser beams, gate computations are constrained only by optical switching rates, removing the qubit shuttling limitation. Our methodology exhibits cutting-edge innovations, featuring thorough optical addressing with sub-micron preciseness, coherence times of qubits surpassing 110 ms, gate operation cycles as brief as 1 microsecond, modular arrays of up to 1500 qubits, error rates below 0.6% for multi-qubit processing, and high-speed non-invasive qubit display with sub-percent atom loss. These elements combined provide an effective framework that can enable dynamic and huge-scale fault-tolerant quantum computing. The system performance evaluations highlight the feasibility of neutral-atom procedures as a solid basis for dynamic, fault-tolerant quantum computing. Our technique, which combines rapidity, precision, and adaptability, signifies a pivotal advancement toward functional quantum devices that can perform real-world applications within optimum time-frames.

Compared with the traditional multi-signature schemes based on mathematical assumptions, a quantum multi-signature protocol (QMSP) has better security due to its security against quantum adversaries. However, most existing QMSPs require both the signers and the verifiers to be quantum participants, who need to have the ability of preparing complex quantum resources and performing various complex quantum operations. In this paper, a semi-quantum multi-signature protocol is proposed. In our protocol, all the singers and verifier are classical parties. By employing simple n-level Z-basis states as quantum resources, the merely perform straightforward permutation operations on quantum states so that the quantum signature is generated, drastically reducing operational costs and offering higher qubit efficiency for the quantum channel. Analyses demonstrate that the protocol can resist various eavesdropping attacks and forgery attacks. Compared with the similar protocols, our protocol has the following merits: (1) the proposed protocol is a semi-quantum one. All the signers and verifier can be classical participants. (2) Its quantum resources are single qubits, which are relatively easier to be prepared than the entangled states. (3) The signers and verifier only need to perform simple operations, such as permutations and Z-basis measurements. (4) It has a better qubit efficiency.

While many quantum key distribution (QKD) protocols offer strong theoretical guarantees, their reliance on ideal single-photon sources and complex hardware introduces implementation level vulnerabilities. The Coherent One-Way (COW) QKD protocol offers a practical and hardware efficient alternative, particularly suited for short-distance deployments such as metropolitan networks. We implemented the COW protocol and focussed on the generation of composable secure keys, which are critical for real-world integration with third-party encryption systems. Achieving such a level of security requires rigorous estimation and control of critical parameters such as detector count rates, QBER, and visibility. We calculate the maximum achievable secret key rate for a composable security parameter (epsilon _{sec} approx 4 times 10^{-9}). Our implementation demonstrates that with stable system operation and precise parameter estimation, an average (epsilon _{sec}) secure key rate of approximately 2 kbps can be achieved. This key rate is sufficient to continuously supply keys to external application entities, enabling secure encryption over public networks.

We study the dynamics of a dressed qubit implemented by a spinless fermion hopping between two lattice sites with each site strongly coupled to a bath of phonons. We employ Lang–Firsov transformation to make the problem tractable perturbatively. Applying time-convolutionless master equation within the polaron frame, we investigate decoherence dynamics of the dressed qubit within the singlet-triplet basis of the system for a wide range of bath spectral densities. It is shown that the coherence persists for longer time scales for large coupling values and shows non-monotonic behavior reflecting the presence of non-Markovianity in the dynamics. Non-Markovianity, characterized by coherence revivals and non-monotonic decay patterns, emerges distinctly depending on the bath spectrum and coupling strengths. Systems coupled to sub-Ohmic baths, whether both or in combination with another type, display pronounced memory effects at relatively small values of couplings. In contrast, combinations involving Ohmic and super-Ohmic baths exhibit noticeable non-Markovianity only at higher couplings.

We analyze the detection of quantum coherent states in N-dimensional (ND) modulation formats, in photonic communications applications, where a constellation of quantum states is prepared at the communications transmitter, and a quantum detection strategy is implemented at the receiver to determine as precisely as possible which quantum state was sent. Due to their importance in photonic communications, we analyze symmetric coherent states constellations with constant average photon number per symbol, in 1D (line), 2D (regular polygons), employing modulation on the optical field quadratures; as well as in 3D Platonic regular convex polyhedra and 4D regular polytopes, with modulation on both the field complex amplitude and the polarization degrees of freedom. As a strategy for detection and discrimination of the received multidimensional quantum optical constellation, we employ the quantum square root method (SRM) for the treatment of the quantum photonic communications system performance, arriving at the evaluation of two main performance measures: the mutual information and the error probability for the analyzed constellations.

Efficient quantum state transfer with three-level systems (qutrits) is fundamental to information science and technology. Here we present a theoretical protocol for implementing state transfer between two superconducting qutrits in circuit quantum electrodynamics. In the regime of resonant interaction, the two qutrits are coupled to the common single-mode cavity fields of transmission line resonators. Based on the data bus of cavity modes, the qutrit–qutrit couplings can be attained effectively. By suitably engineering the qutrit–resonator coupling rates, we perform a one-step operation of desired qutrit state transfer by the technique of shortcuts to adiabaticity. Owing to the rapidness and robustness of quantum operations, the current scheme is insusceptible to environmental decoherence effects and remains insensitive to control parameter errors. Thus, the scheme could offer a promising route towards scalable superconducting qutrit state transfer.

The mining process, which is to add new blocks to the Blockchain by solving complex mathematical problems, traditionally relies on significant computational power. This study introduces a hybrid quantum-classical proof-of-work (PoW) protocol for Blockchain mining, which leverages quantum computing alongside classical algorithms such as SHA-256, Blake2b, and Keccak-256. The protocol incorporates four quantum bits for SHA-256 and Blake2b, with a higher quantum bit count required for Keccak-256. The research evaluates the relationship between qubit count and mining efficiency for both Bitcoin and Ethereum, demonstrating that the proposed protocol achieves temporal performance improvements of 78.17% and 80.48% compared to traditional PoW methods. Despite these advancements, the hybrid protocol’s mining time of 15.47 s is 19% slower than the existing proof-of-stake protocol. The study concludes that while the hybrid protocol enhances mining efficiency, it remains less competitive compared to proof of stake.

In the current NISQ era, the client lacks sufficient quantum capabilities to construct complex quantum neural networks locally. Although the proposed quantum federated learning methods deploy training models on servers with powerful quantum capabilities, challenges remain, such as preparing highly entangled brickwork states and preventing unavoidable leakage of model parameters to the server. Therefore, this paper proposes a quantum federated learning method utilizing measurement-based quantum computation. Firstly, a quantum measurement model based on five-qubit entangled states is constructed to enable the deployment of an encrypted quantum neural network on the server side, with only measurement operations performed on the client side. This ensures that the client achieves the desired rotation gates and angles through measurement operations while performing a quantum one-time pad to encrypt quantum states. This prevents an untrusted server from extracting information about private data, model parameters, and model outputs. Secondly, to ensure the security of the client’s gradient information, a quantum measurement model utilizing three-qubit entangled states is developed to implement a secure aggregation method. Finally, a security analysis demonstrates that the proposed scheme protects the client's private data, model parameters, and model output. Furthermore, we conduct a binary classification experiment on the MNIST dataset using the measurement-based quantum computation framework provided by Paddle quantum, validating the feasibility of the proposed method.