China

Entanglement plays a central role in quantum information processing and quantum physics. However, few effective ways are known to detect the amount of entanglement of an unknown quantum state. Here, we propose a scheme to estimate the entanglement negativity for any bipartition of a composite system. The proposed scheme is based on the random unitary evolution and local measurements on a single-copy quantum state, which is more practical compared with former methods based on collective measurements on many copies of the identical state. Meanwhile, we generalize the scheme to quantify the total correlation. We demonstrate the efficiency of the scheme with statistical analyses and numerical simulations. Our scheme is quite suitable for state-of-the-art quantum platforms, which can serve as a useful benchmarking tool to advance quantum technologies and a probe to study fundamental quantum physics like entanglement dynamics.

Quantum 2020

Single-Copies Estimation of Entanglement Negativity

randomized measurement

single-copy

entanglement negativity

The Institute of Physics and IOP Publishing, in partnership with the Chinese Physical Society (CPS) and the University of Science and Technology of China (USTC) are proud to have brought together the international quantum science community online for this inaugural conference.


Early career and leading researchers from universities, industry and government worldwide came together to share, learn and collaborate on the latest research and emerging areas of high interest across quantum science and technology. The broad themes covered by Quantum 2020 included:

Quantum communication;
Quantum computing and quantum simulation;
Quantum sensing, metrology and imaging;
Quantum information theory, software and algorithms;
Quantum foundations;
Quantum technology in industry.
The four-day event featured talks from world-renowned scientists, interactive poster sessions and two exciting panel discussions on the themes of Quantum Technology in Industry and Quantum Technology Programmes Around the World.


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The Institute of Physics and IOP Publishing, in partnership with the Chinese Physical Society (CPS) and the University of Science and Technology of China (USTC) are proud to have brought together the international quantum science community online for this inaugural conference.

Early career and leading researchers from universities, industry and government worldwide came together to share, learn and collaborate on the latest research and emerging areas of high interest across quantum science and technology. 

technical paper

Quantum antiferromagnet is of fundamental interest as it becomes a fertile ground for studying exotic many-body states including spin liquids and high-temperature superconductors. Compared with condensed matter systems, ultracold gases in optical lattices can be microscopically engineered and provide a unique opportunity for exploring bosonic magnetism and spin dynamics. Here, we report on the creation of a one-dimensional Heisenberg antiferromagnet with ultracold bosons. In a two-component Bose-Hubbard system, we switch the sign of the spin-exchange interaction and realize the isotropic antiferromagnetic Heisenberg model in an extended 70-site chain. Starting from a low-entropy N\'eel-ordered state, the bosonic antiferromagnet is approached via an optimized adiabatic passage. We probe the evolution of staggered magnetization and spin correlations of the system, revealing the coherent establishment of the antiferromagnetism. Furthermore, the characteristic spin-rotational symmetry of the state and its robustness against decoherence are verified. Our experiment demonstrates a novel way for generating many-body spin correlations and exploring exotic forms of magnetism.

Realization of a bosonic antiferromagnet

Continuous variable quantum key distribution (CV-QKD) has made great progress recent years. Throughput of error correction is one of the bottlenecks for CV-QKD. For typical distance of CV-QKD system, the signal-to-noise ratio is low, and a large number of iterations is needed for decoder. Since scheduling strategy is an important factor of the decoder’s convergence rate, in this paper, the performance of three different scheduling strategies (flooding scheduling, layered scheduling by row, layered scheduling by column) is compared. The algorithm complexity, adaptation to the parity check matrix, and throughput performance are studied. For the typical parity check matrix for CV-QKD system, the results show that layered scheduling by column is the best method. Throughput of more than 70 Mbits/s is achieved by this method, which surpasses the record in the literature and can improve the real-time processing capacity of CV-QKD system.

Study on error correction decoder scheduling strategies for continuous variable quantum key distribution system

"HqHop: Hybrid Quantum Hopfield Neural Network for Portfolio Selection

RP Mahajan 
 
Faculty at Dept. of Computer Science & Engineering, SIRT, SAGE University, India
E-mail: rpmahajan.sage@gmail.com ; rpmahajan@yahoo.com

 
Abstract: Classical Hopfield neural networks (CHNN) are known for solving portfolio selection problem for asset management. A Hybrid Quantum Hopfield Neural Network (HqHop) is proposed to solve portfolio selection problem based on Markowitz mean variance approach. Due to the large number of portfolios, the CHNN requires huge memory and processing power. The inbuilt parallelism in CHNN makes it more suitable for quantum based system. This paper details an approach, perhaps the first time, for the solution of portfolio selection problem using the involved concept. The developed HqHop can be used for solving other optimization problems as well.

"

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Single-Copies Estimation of Entanglement Negativity

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Realization of a bosonic antiferromagnet

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