Quantum Information Processing最新文献

The Schmidt number characterizes the quantum entanglement of a bipartite mixed state and plays a significant role in certifying entanglement of quantum states. We derive a Schmidt number criterion based on the trace norm of the correlation matrix obtained from the general symmetric informationally complete measurements. The criterion gives an effective way to quantify the entanglement dimension of a bipartite state with arbitrary local dimensions. We show that this Schmidt number criterion is more effective and superior than other criteria such as fidelity, CCNR (computable cross-norm or realignment), MUB (mutually unbiased bases) and EAM (equiangular measurements) criteria in certifying the Schmidt numbers by detailed examples.

Quantum voting protocol(QVP) allows the voters securely vote by checking the adversary’s eavesdropping on the quantum channels. However, most existing QVPs are based on complex quantum technologies and n-particle entangled states, which impose substantial requirements on quantum equipment. What is more, the larger the parameter n, the more difficult the preparation and preservation of the n-particle entangled states. Furthermore, in most of the protocols, there is an issue of excessive reliance on a single trusted center, who masters the power of both verifying the vote and tracing the voter’s identity, which renders them vulnerable to the security risks resulting from potential abuse of single center’s power. To address these challenges, a semi-quantum voting protocol(SQVP) with decentralization of vote verification and traceability is proposed. In our protocol, the center Trent and the scrutineer Bob are quantum party, while all the voters are classical partners. The center Trent can only get the information on the vote's content without knowing the voter's identity, while the scrutineer Bob can only trace the identity of the voter without knowing the content of the vote. Therefore, our protocol can prevent from the abuse of single center’s power. The protocol can effectively withstand various eavesdropping and forgery attacks. To our knowledge, our protocol is the first SQVP utilizing the Bell state. Compared to similar QVPs, our protocol is more practical while ensuring security.

We investigate a hybrid multi-cavity optomechanical system with interference from a two-level atomic ensemble. The system is composed of three optical cavities and two nanomechanical resonators, with the middle optical cavity being filled with the two-level atomic ensemble. The optical cavity located in the middle has two interaction forces with the two outermost optical cavities. What is more, the system also includes various types of interaction relations, which are the couplings of the optical cavities with the mechanical resonators and the coupling of the optical cavity with the two-level atomic ensemble. In order to study the optical response of optomechanically induced transparency, we modulate the interaction intensity within the system to achieve different electromagnetic induced transparency phenomena. It has been found that under the influence of different parameters, the number and the width of transparency windows increase with an increase in the coupling of the optical cavities with atomic ensemble. In addition, changes in system parameters lead to shifts transparency points, specifically, the distance between the two outermost transparent points also expands when the couplings between the optical cavities and the mechanical resonators increases. We further examine the slow and fast light effects related to phase and group delay in the detection field. Our approach provides great flexibility for controlling electromagnetically induced transparency, presenting substantial potential applications in quantum information processing.

Not all activities in living creatures can be explained by classical dynamics. The application of quantum physics in biology helps to study the unexplained phenomena in cells. More detailed research work is needed rather than rejecting the concept of the intervention of quantum physics in biology. Here, we have used some concepts introduced by Hameroff and Penrose (Hameroff, S et al, Neural Network World 5:793-804, 1996) and some quantum models to show the quantum decoherence in neurons. Assuming a quantum superposition of dimers in microtubules, we have separately presented two types of interaction with its environment. For interaction with a bosonic environment, we have shown that the decoherence time scale depends on a constant factor that depends on the interaction coefficients and amplitude of spectral density. For interaction with a spin environment, we have pointed out one case where the coherent superposition state of a dimer is strong enough to survive against the environmental induced decoherence.

In this paper, a class of narrow-sense constacyclic BCH codes over (mathbb {F}_{q^2}) with length (n=frac{q^{2m}-1}{2left( q^2-1right) }) is studied, where (qge 3) is an odd prime power and (mge 2) is even. The maximum designed distance such that narrow-sense constacyclic BCH codes over (mathbb {F}_{q^2}) with length n containing their Hermitian dual codes is determined. We obtain some new quantum codes by using such narrow-sense constacyclic BCH codes. Our constructions not only have larger designed distance but also have better parameters than the ones in the literature.

In multipartite composite quantum systems, nonproduct states and nonlocally broadcastable states are very important physical resources. In this paper, we first introduce the definition of strong k-product states, strong k-classical states, and strong k-locally broadcastable states; secondly, we propose the concept of the mutual information with respect to k-partition for multipartite quantum states, then define a correlation measure of nonstrong-k-product states based on the mutual information, and discuss some properties of this correlation measure. Finally, we obtain some equivalent and necessary conditions for strong k-locally broadcastable states based on mutual information.

Entanglement-assisted quantum error-correcting codes (EAQECCs) not only can boost the performance of stabilizer quantum error-correcting codes but also can be derived from arbitrary classical linear codes by loosing the self-orthogonal condition and using pre-shared entangled states between the sender and the receiver. It is a challenging work to construct optimal EAQECCs and determine the required number of pre-shared entangled states. Let (mathcal {R}_{t}=mathbb {F}_{q^{2}}+vmathbb {F}_{q^{2}}+v^{2}mathbb {F}_{q^{2}}+cdots +v^{t}mathbb {F}_{q^{2}}), where q is an odd prime power and (v^{t+1}=1). Based on the generalized Gray map that is provided from (mathcal {R}_{t}) to (mathbb {F}_{q^{2}}^{t+1}), some new optimal EAQECCs are constructed from the Gray images of v-constacyclic codes over (mathcal {R}_{t}). Compared with the known ones, our codes have better parameters.

Quantum entanglement plays a pivotal role in quantum information processing. Quantifying quantum entanglement is a challenging and essential research area within the field. This manuscript explores the relationships between bipartite entanglement concurrence, multipartite entanglement concurrence, and genuine multipartite entanglement (GME) concurrence. We derive lower bounds on GME concurrence from these relationships, demonstrating their superiority over existing results through rigorous proofs and numerical examples. Additionally, we investigate the connections between GME concurrence and other entanglement measures, such as tangle and global negativity, in multipartite quantum systems.

Two communicants can make use of quantum dialogue (QD) to exchange their private data in a secure efficient manner without preparing keys ahead. In order to increase the capacity of quantum communication, there were several QD protocols taking a photon in double degrees of freedom as their quantum resources recently. However, although they adopt different approaches to develop such a photon, these QD protocols have a common point—all making one degree of freedom represent only one bit. This paper proposes a novel method for one degree of freedom to symbolize two bits. Thus, its information density is twice that of these existing protocols. This will bring about a new QD of high information density. In a certain degree, its information-theoretical efficiencies can reach as high as 83.33%, more than the current maximum—66.67%. Moreover, the proposed method can also improve on cost and efficiency. Finally, the presented QD protocol is analysed turning out secure and without information leakage. Consequently, this work provides us a desirable QD alternative.

We consider quantum two-player games and investigate the effect of the degree of entanglement on Nash equilibria. The purpose of this paper is to characterize Nash equilibria by their payoff patterns. We derive all Nash equilibrium payoff patterns that are realized by at least one quantum game.