Breaking universal limitations on quantum conference key agreement without quantum memory

Quantum conference key agreement is an important cryptographic primitive for future quantum network. Realizing this primitive requires high-brightness and robust multiphoton entanglement sources, which is challenging in experiment and unpractical in application because of limited transmission distance caused by channel loss. Here we report a measurement-device-independent quantum conference key agreement protocol with enhanced transmission efficiency over lossy channel. With spatial multiplexing nature and adaptive operation, our protocol can break key rate bounds on quantum communication over quantum network without quantum memory. Compared with previous work, our protocol shows superiority in key rate and transmission distance within the state-of-the-art technology. Furthermore, we analyse the security of our protocol in the composable framework and evaluate its performance in the finite-size regime to show practicality. Based on our results, we anticipate that our protocol will play an indispensable role in constructing multipartite quantum network

Secure Anonymous Conferencing in Quantum Networks

Users of quantum networks can securely communicate via so-called (quantum) conference key agreement—making their identities publicly known. In certain circumstances, however, communicating users demand anonymity. Here, we introduce a security framework for anonymous conference key agreement with different levels of anonymity, which is inspired by the ε-security of quantum key distribution. We present efficient and noise-tolerant protocols exploiting multipartite Greenberger-Horne-Zeilinger (GHZ) states and prove their security in the finite-key regime. We analyze the performance of our protocols in noisy and lossy quantum networks and compare with protocols that only use bipartite entanglement to achieve the same functionalities. Our simulations show that GHZ-based protocols can outperform protocols based on bipartite entanglement and that the advantage increases for protocols with stronger anonymity requirements. Our results strongly advocate the use of multipartite entanglement for cryptographic tasks involving several users

Secure Anonymous Conferencing in Quantum Networks

Users of quantum networks can securely communicate via so-called (quantum) conference key agreement—making their identities publicly known. In certain circumstances, however, communicating users demand anonymity. Here, we introduce a security framework for anonymous conference key agreement with different levels of anonymity, which is inspired by the ε-security of quantum key distribution. We present efficient and noise-tolerant protocols exploiting multipartite Greenberger-Horne-Zeilinger (GHZ) states and prove their security in the finite-key regime. We analyze the performance of our protocols in noisy and lossy quantum networks and compare with protocols that only use bipartite entanglement to achieve the same functionalities. Our simulations show that GHZ-based protocols can outperform protocols based on bipartite entanglement and that the advantage increases for protocols with stronger anonymity requirements. Our results strongly advocate the use of multipartite entanglement for cryptographic tasks involving several users

New Protocols for Conference Key and Multipartite Entanglement Distillation

We approach two interconnected problems of quantum information processing in networks: Conference key agreement and entanglement distillation, both in the so-called source model where the given resource is a multipartite quantum state and the players interact over public classical channels to generate the desired correlation. The first problem is the distillation of a conference key when the source state is shared between a number of legal players and an eavesdropper; the eavesdropper, apart from starting off with this quantum side information, also observes the public communication between the players. The second is the distillation of Greenberger-Horne-Zeilinger (GHZ) states by means of local operations and classical communication (LOCC) from the given mixed state. These problem settings extend our previous paper [IEEE Trans. Inf. Theory 68(2):976-988, 2022], and we generalise its results: using a quantum version of the task of communication for omniscience, we derive novel lower bounds on the distillable conference key from any multipartite quantum state by means of non-interacting communication protocols. Secondly, we establish novel lower bounds on the yield of GHZ states from multipartite mixed states. Namely, we present two methods to produce bipartite entanglement between sufficiently many nodes so as to produce GHZ states. Next, we show that the conference key agreement protocol can be made coherent under certain conditions, enabling the direct generation of multipartite GHZ states

Secrets of Success: Identifying Success Factors in Institutional Repositories

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PresentationsDate: 2009-05-19 08:30 AM – 09:30 AMThere is little agreement on which factors lead to successful institutional repositories. Researchers primarily cite content recruitment and services as key factors; however, there has also been discussion of measuring IR success in terms of how well the IR furthers the overall goals of the library. This paper examines the topic of IRs and success. Our findings are based on a comparative case study of five IRs in colleges and universities. We argue that success should be measured by both internal (e.g., content or services) as well as external factors - how well the IR fulfills or brings the library closer to achieving its long-term goals in terms of service to the academic community.Institute of Museum and Library Service

Research priorities for data collection and management within global acute and emergency care systems.

Barriers to global emergency care development include a critical lack of data in several areas, including limited documentation of the acute disease burden, lack of agreement on essential components of acute care systems, and a lack of consensus on key analytic elements, such as diagnostic classification schemes and regionally appropriate metrics for impact evaluation. These data gaps obscure the profound health effects of lack of emergency care access in low- and middle-income countries (LMICs). As part of the Academic Emergency Medicine consensus conference "Global Health and Emergency Care: A Research Agenda," a breakout group sought to develop a priority research agenda for data collection and management within global emergency care systems