Revisiting controlled quantum secure direct communication using a non-symmetric quantum channel with quantum superdense coding

Secure communication over generalised quantum multiple access channels

We investigate the security of generalized quantum multiple-access channels. We provide the formula for the achievable rate region of secure communication in the scenario of two senders and a single receiver. We explicitly specify a protocol for secure communication in this scenario, which employs superdense coding. The protocol is based on the distribution of a tripartite GHZ state. It allows for both symmetric and asymmetric key distribution whereby one of the senders can have twice the capacity of the other sender. We prove the security of the protocol against general quantum attacks, analy…

High-capacity quantum secure direct communication based on quantum hyperdense coding with hyperentanglement

We present a quantum hyperdense coding protocol with hyperentanglement in polarization and spatial-mode degrees of freedom of photons first and then give the details for a quantum secure direct communication (QSDC) protocol based on this quantum hyperdense coding protocol. This QSDC protocol has the advantage of having a higher capacity than the quantum communication protocols with a qubit system. Compared with the QSDC protocol based on superdense coding with $d$-dimensional systems, this QSDC protocol is more feasible as the preparation of a high-dimension quantum system is more difficult th…

基于信息熵度量增强量子密集编码鲁棒性

Enhancing Quantum Dense Coding Robustness Using Information Entropy-Based Metrics

针对量子密集编码受噪声和退相干影响的问题，提出集成五量子比特完美码与全局自适应纯化的协议，通过监测量子失协QD和形成纠缠EoF提升鲁棒性和吞吐量，为高容量量子互联网提供路径。

Quantum one-time tables for unconditionally secure qubit-commitment

The commodity-based cryptography is an alternative approach to realize conventionally impossible cryptographic primitives such as unconditionally secure bit-commitment by consuming pre-established correlation between distrustful participants. A unit of such classical correlation is known as the one-time table (OTT). In this paper, we introduce a new example besides quantum key distribution in which quantum correlation is useful for cryptography. We propose a scheme for unconditionally secure qubit-commitment, a quantum cryptographic primitive forbidden by the recently proven no-masking theorem…

Four-dimensional entanglement distribution over 100 km

High-dimensional quantum entanglement can enrich the functionality of quantum information processing. For example, it can enhance the channel capacity for linear optic superdense coding and decrease the error rate threshold of quantum key distribution. Long-distance distribution of a high-dimensional entanglement is essential for such advanced quantum communications over a communications network. Here, we show a long-distance distribution of a four-dimensional entanglement. We employ time-bin entanglement, which is suitable for a fibre transmission, and implement scalable measurements for the …

量子键盘记录

Quantum keystroke logging

本文在基于GKP的量子通信中提出“量子键盘记录”漏洞，证明组织即使不组装完整编码贝尔态，也能在超密编码过程中无痕提取输入信息，从而揭示纠错逻辑态下的安全性缺陷。

Enhanced No-Go Theorem for Quantum Position Verification

Based on the instantaneous nonlocal quantum computation (INQC), Buhrman et al. proposed an excellent attack strategy to quantum position verification (QPV) protocols in 2011, and showed that, if the colluding adversaries are allowed to previously share unlimited entangled states, it is impossible to design an unconditionally secure QPV protocol in the previous model. Here, trying to overcome this no-go theorem, we find some assumptions in the INQC attack, which are implicit but essential for the success of this attack, and present three different QPV protocols where these assumptions are not s…

量子 $X$-安全 $B$-拜占庭 $T$-共谋私有信息检索

Quantum $X$-Secure $B$-Byzantine $T$-Colluding Private Information Retrieval

本文首次在量子私有信息检索中形式化定义拜占庭服务器的能力，证明其因量子编码而强于经典情形，并提出基于跨子空间对齐的方案，在某些情况下实现超密编码增益。

基于时间纠缠的高维量子区块链协议

A High-Dimensional Quantum Blockchain Protocol Based on Time- Entanglement

本研究提出基于时间纠缠和高维量子编码的区块链协议，利用量子相关性生成密钥，实现安全验证与抗篡改功能。

Multi-mode Time-delay Interferometer for Free-space Quantum Communication

Quantum communication schemes such as quantum key distribution (QKD) and superdense teleportation provide unique opportunities to communicate information securely. Increasingly, optical communication is being extended to free-space channels, but atmospheric turbulence in free-space channels requires optical receivers and measurement infrastructure to support many spatial modes. Here we present a multi-mode, Michelson-type time-delay interferometer using a field-widened design for the measurement of phase-encoded states in free-space communication schemes. The interferometer is constructed usin…

$N$-和盒：多对一量子网络上线性计算的一种抽象

$N$-Sum Box: An Abstraction for Linear Computation over Many-to-one Quantum Networks

该工作提出$N$-和盒抽象，以黑盒方式概括量子多对一网络中的线性计算，并刻画可行转移矩阵，应用于量子私有信息检索和批量矩阵乘法，实现通信成本优化。

量子环全归约：分布式学习的通信与隐私优势

Quantum ring all-reduce: communication and privacy advantages for distributed learning

提出量子环全归约协议，利用预共享纠缠和超密编码将每链路在线通信量减半，并通过验证纠缠实现信息论安全的可组合ε-安全聚合，同时获得通信与隐私优势。