Quantum NETwork: from theory to practice

The quantum internet is envisioned as the ultimate stage of the quantum revolution, which surpasses its classical counterpart in various aspects, such as the efficiency of data transmission, the security of network services, and the capability of information processing. Given its disruptive impact on the national security and the digital economy, a global race to build scalable quantum networks has already begun. With the joint effort of national governments, industrial participants and research institutes, the development of quantum networks has advanced rapidly in recent years, bringing the first primitive quantum networks within reach. In this work, we aim to provide an up-to-date review of the field of quantum networks from both theoretical and experimental perspectives, contributing to a better understanding of the building blocks required for the establishment of a global quantum internet. We also introduce a newly developed quantum network toolkit to facilitate the exploration and evaluation of innovative ideas. Particularly, it provides dual quantum computing engines, supporting simulations in both the quantum circuit and measurement-based models. It also includes a compilation scheme for mapping quantum network protocols onto quantum circuits, enabling their emulations on real-world quantum hardware devices. We showcase the power of this toolkit with several featured demonstrations, including a simulation of the Micius quantum satellite experiment, a testing of a four-layer quantum network architecture with resource management, and a quantum emulation of the CHSH game. We hope this work can give a better understanding of the state-of-the-art development of quantum networks and provide the necessary tools to make further contributions along the way.Comment: 36 pages, 33 figures; comments are welcom

Hybrid quantum-classical and quantum-inspired classical algorithms for solving banded circulant linear systems

Solving linear systems is of great importance in numerous fields. In particular, circulant systems are especially valuable for efficiently finding numerical solutions to physics-related differential equations. Current quantum algorithms like HHL or variational methods are either resource-intensive or may fail to find a solution. We present an efficient algorithm based on convex optimization of combinations of quantum states to solve for banded circulant linear systems whose non-zero terms are within distance $K$ of the main diagonal. By decomposing banded circulant matrices into cyclic permutations, our approach produces approximate solutions to such systems with a combination of quantum states linear to $K$, significantly improving over previous convergence guarantees, which require quantum states exponential to $K$. We propose a hybrid quantum-classical algorithm using the Hadamard test and the quantum Fourier transform as subroutines and show its PromiseBQP-hardness. Additionally, we introduce a quantum-inspired algorithm with similar performance given sample and query access. We validate our methods with classical simulations and actual IBM quantum computer implementation, showcasing their applicability for solving physical problems such as heat transfer.Comment: 21 pages, 12 figure

Applicability of Measurement-based Quantum Computation towards Physically-driven Variational Quantum Eigensolver

Recently variational quantum algorithms have been considered promising quantum computation methods, where the mainstream algorithms are based on the conventional quantum circuit scheme. However, in the Measurement-Based Quantum Computation (MBQC) scheme, multi-qubit rotation operations are implemented with a straightforward approach that only requires a constant number of single-qubit measurements, providing potential advantages in both resource cost and fidelity. The structure of Hamiltonian Variational Ansatz (HVA) aligns well with this characteristic. In this paper, we propose an efficient measurement-based quantum algorithm for quantum many-body system simulation tasks, alluded to as Measurement-Based Hamiltonian Variational Ansatz (MBHVA). We then demonstrate its effectiveness, efficiency, and advantages with two quantum many-body system models. Numerical experiments show that MBHVA is expected to reduce resource overhead compared to the construction of quantum circuits especially in the presence of large-scale multi-qubit rotation operations. Furthermore, when compared to measurement-based Hardware Efficient Ansatz (MBHEA) on quantum many-body system problems, MBHVA also demonstrates superior performance. We conclude that the MBQC scheme is potentially better suited for quantum simulation than the circuit-based scheme in terms of both resource efficiency and error mitigation

Entire genome sequence analysis of genotype IX Newcastle disease viruses reveals their early-genotype phylogenetic position and recent-genotype genome size

<p>Abstract</p> <p>Background</p> <p>Six nucleotide (nt) insertion in the 5'-noncoding region (NCR) of the nucleoprotein (NP) gene of Newcaslte disease virus (NDV) is considered to be a genetic marker for recent genotypes of NDV, which emerged after 1960. However, F48-like NDVs from China, identified a 6-nt insert in the NP gene, have been previously classified into genotype III or genotype IX.</p> <p>Results</p> <p>In order to clarify their phylogenetic position and explore the origin of NDVs with the 6-nt insert and its significance in NDV evolution, we determined the entire genome sequences of five F48-like viruses isolated in China between 1946 and 2002 by RT-PCR amplification of overlapping fragments of full-length genome and rapid amplification of cDNA ends. All the five NDV isolates shared the same genome size of 15,192-nt with the recent genotype V-VIII viruses whereas they had the highest homology with early genotype III and IV isolates.</p> <p>Conclusions</p> <p>The unique characteristic of the genome size and phylogenetic position of F48-like viruses warrants placing them in a separate geno-group, genotype IX. Results in this study also suggest that genotype IX viruses most likely originate from a genotype III virus by insertion of a 6-nt motif in the 5'-NCR of the NP gene which had occurred as early as in 1940 s, and might be the common origin of genotype V-VIII viruses.</p

Novel Reassortant Highly Pathogenic Avian Influenza (H5N5) Viruses in Domestic Ducks, China

In China, domestic ducks and wild birds often share the same water, in which influenza viruses replicate preferentially. Isolation of 2 novel reassortant highly pathogenic avian influenza (H5N5) viruses from apparently healthy domestic ducks highlights the role of these ducks as reassortment vessels. Such new subtypes of influenza viruses may pose a pandemic threat

Deficiency of Pten accelerates mammary oncogenesis in MMTV-Wnt-1 transgenic mice

Background: Germline mutations in the tumor suppressor PTEN predispose human beings to breast cancer, and genetic and epigenetic alterations of PTEN are also detected in sporadic human breast cancer. Germline Pten mutations in mice lead to the development of a variety of tumors, but mammary carcinomas are infrequently found, especially in mice under the age of six months. Results: To better understand the role of PTEN in breast tumor development, we have crossed Pten heterozygous mice to MMTV-Wnt-1 transgenic mice that routinely develop ductal carcinomas in the mammary gland. Female Wnt-1 transgenics heterozygous for Pten developed mammary tumors earlier than Wnt-1 transgenics that were wild type for Pten. In most tumors arising in Pten heterozygotes, the Pten wild-type allele was lost, suggesting that cells lacking Pten function have a growth advantage over cells retaining a wild type allele. Tumors with LOH contained high levels of activated AKT/PKB, a downstream target of the PTEN/PI3K pathway. Conclusions: An animal model has been developed in which the absence of Pten collaborates with Wnt-1 to induce ductal carcinoma in the mammary gland. This animal model may be useful for testing therapies specific for tumors deregulated in the PTEN/PI3K/AKT pathway

Sequential Reassortments Underlie Diverse Influenza H7N9 Genotypes in China

Initial genetic characterizations have suggested that the influenza A (H7N9) viruses responsible for the current outbreak in China are novel reassortants. However, little is known about the pathways of their evolution and, in particular, the generation of diverse viral genotypes. Here we report an in-depth evolutionary analysis of whole-genome sequence data of 45 H7N9 and 42 H9N2 viruses isolated from humans, poultry, and wild birds during recent influenza surveillance efforts in China. Our analysis shows that the H7N9 viruses were generated by at least two steps of sequential reassortments involving distinct H9N2 donor viruses in different hosts. The first reassortment likely occurred in wild birds and the second in domestic birds in east China in early 2012. Our study identifies the pathways for the generation of diverse H7N9 genotypes in China and highlights the importance of monitoring multiple sources for effective surveillance of potential influenza outbreaks.National Natural Science Foundation (China) (31125016)National Natural Science Foundation (China) (31371338)National Center for Biotechnology Information (U.S.) (Major National Earmark Project for Infectious Diseases, 2013ZX10004611-002)National Basic Research Program of China (973 Program)National Basic Research Program of China (973 Program, grant, 2009CB918503)National Science and Technology Major Projects (2012ZX10004214001002)Jiangsu Sheng (China) (Priority Academic Program Development of Jiangsu Higher Education Institutions)National Natural Science Foundation (China) (31100950)MIT International Science and Technology Initiative

Highly pathogenic avian influenza H5N6 viruses exhibit enhanced affinity for human type sialic acid receptor and in-contact transmission in model ferrets

Since May 2014, highly pathogenic avian influenza H5N6 virus has been reported to cause six severe human infections three of which were fatal. The biological properties of this subtype, in particular its relative pathogenicity and transmissibility in mammals, are not known. We characterized the virus receptor-binding affinity, pathogenicity, and transmissibility in mice and ferrets of four H5N6 isolates derived from waterfowl in China from 2013-2014. All four H5N6 viruses have acquired a binding affinity for human-like SA alpha 2,6Gal-linked receptor to be able to attach to human tracheal epithelial and alveolar cells. The emergent H5N6 viruses, which share high sequence similarity with the human isolate A/Guangzhou/39715/2014 (H5N6), were fully infective and highly transmissible by direct contact in ferrets but showed less-severe pathogenicity than the parental H5N1 virus. The present results highlight the threat of emergent H5N6 viruses to poultry and human health and the need to closely track their continual adaptation in humans

Multiple-Clade H5N1 Influenza Split Vaccine Elicits Broad Cross Protection against Lethal Influenza Virus Challenge in Mice by Intranasal Vaccination

Background: The increase in recent outbreaks and unpredictable changes of highly pathogenic avian influenza (HPAI) H5N1 in birds and humans highlights the urgent need to develop a cross-protective H5N1 vaccine. We here report our development of a multiple-clade H5N1 influenza vaccine tested for immunogenicity and efficacy to confer cross-protection in an animal model. Methodology/Principal Findings: Mice received two doses of influenza split vaccine with oil-in-water emulsion adjuvant SP01 by intranasal administration separated by two weeks. Single vaccines (3 mg HA per dose) included rg-A/Vietnam/1203/ 2004(Clade 1), rg-A/Indonesia/05/2005(Clade 2.1), and rg-A/Anhui/1/2005(Clade 2.3.4). The trivalent vaccine contained 1 mg HA per dose of each single vaccine. Importantly, complete cross-protection was observed in mice immunized using trivalent vaccine with oil-in-water emulsion adjuvant SP01 that was subsequently challenged with the lethal A/OT/SZ/097/03 influenza strain (Clade 0), whereas only the survival rate was up to 60 % in single A/Anhui/1/2005 vaccine group. Conclusion/Significance: Our findings demonstrated that the multiple-clade H5N1 influenza vaccine was able to elicit a cross-protective immune response to heterologous HPAI H5N1 virus, thus giving rise to a broadly cross-reactive vaccine to potential prevention use ahead of the strain-specific pandemic influenza vaccine in the event of an HPAI H5N1 influenza outbreak. Also, the multiple-clade adjuvanted vaccine could be useful in allowing timely initiation of vaccination agains