Cost-efficient quantum access network boosts practical deployment of quantum key distribution network

The security of information is not assured over extended periods,especially with the rapid advancement of quantum computers.To address this challenge,quantum cryptography,rooted in quantum physics,offers comprehensive toolkits for key distribution[1],secret sharing[2],digital signatures[3]and other cryptographic tasks[4]with information-theoretical security.The feasibility of quantum cryptography,particularly quantum key distribution(QKD)。

Experimental quantum secret sharing based on phase encoding of coherent states

Quantum secret sharing(QSS)is one of the basic communication primitives in future quantum networks which addresses part of the basic cryptographic tasks of multiparty communication and computation.Nevertheless,it is a challenge to provide a practical QSS protocol with security against general attacks.A QSS protocol that balances security and practicality is still lacking.Here,we propose a QSS protocol with simple phase encoding of coherent states among three parties.Removing the requirement of impractical entangled resources and the need for phase randomization,our protocol can be implemented with accessible technology.We provide the finite-key analysis against coherent attacks and implement a proof-of-principle experiment to demonstrate our scheme’s feasibility.Our scheme achieves a key rate of 85.3 bps under a 35 d B channel loss.Combined with security against general attacks and accessible technology,our protocol is a promising candidate for practical multiparty quantum communication networks.

Experimental Quantum Advantage with Quantum Coupon Collector

An increasing number of communication and computational schemes with quantum advantages have recently been proposed,which implies that quantum technology has fertile application prospects.However,demonstrating these schemes experimentally continues to be a central challenge because of the difficulty in preparing high-dimensional states or highly entangled states.In this study,we introduce and analyze a quantum coupon collector protocol by employing coherent states and simple linear optical elements,which was successfully demonstrated using realistic experimental equipment.We showed that our protocol can significantly reduce the number of samples needed to learn a specific set compared with the classical limit of the coupon collector problem.We also discuss the potential values and expansions of the quantum coupon collector by constructing a quantum blind box game.The information transmitted by the proposed game also broke the classical limit.These results strongly prove the advantages of quantum mechanics in machine learning and communication complexity.

Quantum Neural Network for Quantum Neural Computing

Neural networks have achieved impressive breakthroughs in both industry and academia.How to effectively develop neural networks on quantum computing devices is a challenging open problem.Here,we propose a new quantum neural network model for quantum neural computing using(classically controlled)single-qubit operations and measurements on real-world quantum systems with naturally occurring environment-induced decoherence,which greatly reduces the difficulties of physical implementations.Our model circumvents the problem that the state-space size grows exponentially with the number of neurons,thereby greatly reducing memory requirements and allowing for fast optimization with traditional optimization algorithms.We benchmark our model for handwritten digit recognition and other nonlinear classification tasks.The results show that our model has an amazing nonlinear classification ability and robustness to noise.Furthermore,our model allows quantum computing to be applied in a wider context and inspires the earlier development of a quantum neural computer than standard quantum computers.