Quantum Information Processing最新文献

The problem of revocation of quantum states after sharing is interesting, and we ask: Is it possible for a dealer to revoke the state once shared, before the reconstruction process? Additional resources like bell states are used to help the dealer to get back the state [1]. In a three-party scenario, we show an independent way to revoke, if, for any reason, the dealer is not sure about the intention of the/any reconstructor. In general, the classical outcomes of the dealer in sharing phase are needed, to be able to reconstruct the state perfectly. When both the shareholders are dishonest^a, and without the dealer’s knowledge, collude to reconstruct, they always have some chance of succeeding. This is addressed by giving more control to the dealer by making him/her to have a quantum share as well. We give a sharing and revocation protocol with a four-qubit entangled resource shared among three parties (two qubits with the dealer and one each with the shareholders). We further consider a class of four-qubit pure entangled states as resource and explicitly find the range of parameters for which the protocol will be successful.

This study explores climate change by predicting methane emissions in North Africa using classical and quantum deep learning methods. Using data from Sentinel-5P, we developed hybrid quantum–classical models, such as quantum long short-term memory (QLSTM) and quantum-gated recurrent unit networks (QGRUs), along with a novel hybrid architecture combining quantum convolutional neural networks (QCNNs) with LSTM and GRU, namely QCNN-LSTM and QCNN-GRU. The results show that these quantum models, especially the proposed hybrid architectures, outperform classical models by approximately seven percent in root-mean-squared error with fewer training epochs. These findings highlight the potential of quantum methodologies for enhancing environmental monitoring accuracy. Future research will aim to refine model performance, incorporate explainable AI techniques, and expand to forecasting other greenhouse gases, contributing to climate change mitigation efforts.

Code-based post-quantum cryptography is seeing an unprecedented growth due to its significance in addressing the security threats posed by quantum computers toward digital communication, leveraging its strength from the well-known hard problems of coding theory. Code-based cryptosystems are vulnerable to attacks that exploit the inherent structure of the underlying code, compromising security in many cases. Although McEliece cryptosystem with Goppa codes provide substantial resistance, this comes at the cost of huge key sizes, limiting their practicality. The proposed work, dynamic code-based McEliece cryptosystem, introduces the notion of dynamicity to the code-based cryptosystem and intensifies the random nature necessary to overcome the attacks. Unlike the conventional schemes that rely on a fixed underlying code and its generator matrix, our approach dynamically changes the code structure in response to trigger events to create cipher keys. This dynamic code transformation preserves the core efficiency of the cipher while significantly improving security against structural attacks, decoding attacks and side channel analysis. The proposed scheme retains IND-CPA security under standard assumptions while also rendering chosen ciphertext attacks significantly challenging. Our work establishes a new direction for enhancing the security of code-based encryption in practical applications.

In recent years, the quantum signature protocol has been an important research topic due to its security against quantum adversaries. Although lots of quantum signature protocols have been presented, their security lacks the support of security model and formal security proof. Especially, their security against adaptively chosen-message attack cannot be proved. Some quantum signature protocols have exposed various security vulnerabilities due to their design defects and informal security analysis. In this paper, based on the single particles, a quantum signature protocol with formal security proof is proposed. In this protocol, the signatory signs the message by cloning the particles and encrypting their states with key-controlled unitary operations. Compared with other similar signature protocols, the advantages of this protocol are as follows: (1) The security of this protocol against forgery attack can be proved with formal security proof under the security model. Its security strictly depends on the principle of quantum unclonability. (2) The security proof need not use the assumption of random oracle. (3) The protocol need not prepare decoy particles for eavesdropping detection, thus saving quantum sources and simplifying the protocol. (4) In the protocol, it is unnecessary to prepare entangled quantum particles. (5) The qubit efficiency reaches 50%, even if the decoy particles are counted.

Quantum battery has enormous potential for development, and quantum battery capacity is an important indicator of quantum battery. In this work, we mainly study the evolution of quantum battery capacity of GHZ state and GHZ-like states under Markovian channels in the tripartite system. We find that under the depolarizing channel and bit-phase flip channel, the battery capacity shows a brief sudden death of the capacity. And we also find that under the dephasing channel, the battery capacity gradually decreases and tends to a constant, that is, the frozen capacity. We show that the battery capacity monotonically decreases for GHZ state under the amplitude damping channel on the first subsystem. And we study the variation of capacity under the Markovian channels n times on the first subsystem using the GHZ state. We can observe that under the amplitude damping and dephasing channels, the battery capacity decreases and tends to a constant, i.e. frozen capacity, and the larger n, the earlier this phenomenon occurs. We also investigate the evolution of capacity under three independent same type Markovian channels. We have also conducted corresponding research on GHZ-like states.

The characteristic quantities and their relationships in the context of quantum teleportation (QT) of an arbitrary qubit state (AQS), where the initial state (IS) of the quantum channel (QC) is a Bell-like state (BLS), have been investigated. The qubits of the QC are independently affected by an amplitude-damping noise environment (ADNE). We have derived analytical expressions for the complementary relationship between the purity measure (PM) of the channel and the entanglement measures (EMs) between each qubit of the channel and the environmental qubit (EQ). Additionally, we have established analytical expressions describing the dependence of the average quantum fidelity (AQF) of the protocol on the channel PM, the channel EM, the bipartite EMs involving channel and EQs, as well as the multipartite entanglement between the channel qubits (CQs) and the EQs. Based on these relationships, we have revealed the physical mechanism underlying the enhancement or non-enhancement of the average fidelity (AF) when the remaining CQ is affected by amplitude-damping noise (ADN). Furthermore, we have analyzed the optimization process of the AF for two protocols in which the IS of the QC is chosen as a BLS.

This paper investigates the private classical capacity region of classical–quantum broadcast channel with two legitimate receivers and one eavesdropper. We discuss four communication scenarios with respect to the confidential message transmission and the capability of receivers. We introduce auxiliary messages and use the superposition coding and quantum-typical projectors; this will ensure that the auxiliary rate can protect confidential messages from Eve, and the cumulative rate remain legitimate receivers decoding capacity. On the ground, we obtain the capacity regions for four different situations.

In this paper, we first study an l-linear complementary pair (abbreviated to l-LCP) of codes over the non-chain ring (R=mathbb {F}_q+umathbb {F}_q+ vmathbb {F}_q+uvmathbb {F}_q) with (u^2=u,v^2=v, uv=vu). Then we provide a method of constructing asymmetric entanglement-assisted quantum error-correcting (abbreviated to AEAQEC) codes from an l-LCP of codes over R by using CSS. To enrich the variety of available AEAQEC codes, some new AEAQEC codes are given in the sense that their parameters are different from all the previous constructions.

We present a method for bidirectional teleportation of a single qubit using quantum walks on two independent one-dimensional lattices and two independent cycles with four vertices, employing nearest-neighbor jumps with coin outcomes. In addition, we discuss two different methods for two-qubit teleportation by employing nearest-neighbor jumps and next-nearest-neighbor jumps with a single coin and two coins, respectively. Finally, it is demonstrated that the two-qubit single-jump and the two-jump quantum walk teleportation schemes yield the same results.

We present a three-qubit quantum state tomography scheme requiring a set of 17 measurement settings, significantly reducing the experimental overhead compared to the conventional 63 Pauli measurement settings. Using IBM’s 127-qubit open-access quantum processor ibm_osaka, we prepare the three-qubit W state and employ our tomography scheme to reconstruct it. Additionally, we implement a two-qubit tomography protocol, involving 7 measurement settings, on ibm_osaka to reconstruct two of the two-qubit marginals of the W state. This serves as a proof-of-principle demonstration of the well-known theoretical result that any two of the two-qubit reduced density matrices can uniquely determine most of the whole three-qubit pure states. We show that the fidelity of the W state reconstructed from its two-qubit subsystems is consistently larger than that obtained from the full three-qubit tomography, highlighting the practical advantage of the subsystem-based tomography approach.