In quantum cloud environment, most application protocols have the problems of using a lot of quantum resources, high communication costs, and inability to check the honesty of cloud server. Therefore, a semi-quantum key agreement protocol based on GHZ-like state with a dishonest delegated measuring center is proposed. In our protocol, the application system consists of a quantum cloud server which only needs to prepare GHZ-like states and distributes all the particles to other participants, a quantum measuring center which performs complicated quantum measurement, such as X-base measurement and Bell measurement, and many classical semi-quantum participants which perform key agreement. Our protocol has many advantages. First, our protocol removes the assumption of honest or semi-honest cloud server because the dishonesty of cloud sever can be checked by delegated measuring center and classical semi-quantum participants. Second, the dishonesty of measuring center can also be found by classical semi-quantum participants through joint measurement. Third, only classical semi-quantum participants can obtain random shared key even if quantum cloud server and measuring center are interested in shared keys. Fourth, a large number of participants may be semi-quantum users which saving a lot of quantum resources. Our protocol is especially suitable for applications such as a large number of classical users arbitrarily performing key agreement in a real cloud environment which only need fewer resources, being easy to implement, and controllable. Security analysis and efficiency analysis show that our protocol can not only effectively resist external and internal attacks, but also resist collusion attack, which is more efficient than similar protocols.
Quantum Private Information Retrieval (QPIR) allows a user (Alice) to retrieve a database item from the database owned by the database holder (Bob) in such a way that Alice can query only the database item she wants, but cannot get other items, and Bob does not know which item Alice queries. However, the real quantum channel between Alice and Bob is noisy, and the noise may result in not only the chance that Alice obtains a false item, but also that both parties may cheat by camouflaging themselves with noise. In this paper, we use the decoherence-free subspace (DFS) for QPIR, which we call DFS-QPIR. The DFS-QPIR protocol removes the effect of the channel noise on the errors in the retrieved item so that two parties cannot cheat by replacing the noisy channel with a noiseless one. It can work over a collective noisy channel while retaining high reliability, database security and user privacy simultaneously. While only the collective unitary noise is taken into account, the proposed DFS-QPIR protocol can be straightforwardly extended to more general collective noise channel.
At present, decoherence continuous-time quantum walks are only based on measurement decoherence, but a new broken-line noise model for continuous-time quantum walks on the cycle is proposed. In this scheme, we first construct the Hamiltonian H according to four cases including no broken links, the link to the left of the node is broken, the link to the right of the node is broken, and both links are broken, and then the probability of a walker is reconstructed. The analysis shows that with the increase of the probability of disconnection, the oscillation of the walk gradually weakens and becomes a peak distribution, and with the continuous increase of the walk time, the probability distribution of each vertex tends to be uniform. In addition, we also analyze the mixing time of this walk model and find that a small amount of broken chain decoherence can help reduce the mixing time, thereby improving the performance of quantum walks.
Quantum key agreement (QKA) permits participants to constitute a shared key on a quantum channel, while no participants can independently determine the shared key. However, existing Measurement-device-independent (MDI) protocols cannot resist channel noise, and noise-resistant QKA protocols cannot resist side-channel attacks caused by equipment defects. In this paper, we design a MDI-QKA protocol against collective-dephasing noise based on GHZ states. First, in our protocol, Alice and Bob prepare a certain number of GHZ states respectively, and then send two particles of each GHZ state to Charlie for bell measurement. Results are that Alice and Bob can obtain Bell states through entanglement exchange with the help of dishonest Charlie. Meanwhile ensures the transmission process noise-resisted. Then, Alice and Bob encode their key components to the particle in their hands and construct logical quantum states against collective noise through additional particles and CNOT operation to implement MDI-QKA. Compared with existing MDI-QKA protocols, our protocol uses logical quantum states during particle transfers, which makes the protocol immune to collective‑dephasing noise, and therefore improving the final key rate. Security analysis shows that our protocol can resist common insider and outsider attacks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.