Tsirelson Polytopes and Randomness Generation

Approaching Tsirelson's bound in a photon pair experiment

Quantum theory introduces a cut between the observer and the observed system, but does not provide a definition of what is an observer. Based on an informational definition of observer, Grinbaum has recently predicted an upper bound on bipartite correlations in the Clauser-Horne-Shimony-Holt (CHSH) Bell scenario equal to 2.82537, which is slightly smaller than the Tsirelson bound of standard quantum theory, but is consistent with all the available experimental results. Not being able to exceed Grinbaum's limit would support that quantum theory is only an effective description of a more fundame…

Quantum Correlations in the Minimal Scenario

In the minimal scenario of quantum correlations, two parties can choose from two observables with two possible outcomes each. Probabilities are specified by four marginals and four correlations. The resulting four-dimensional convex body of correlations, denoted $\mathcal{Q}$, is fundamental for quantum information theory. We review and systematize what is known about $\Qm$, and add many details, visualizations, and complete proofs. In particular, we provide a detailed description of the boundary, which consists of three-dimensional faces isomorphic to elliptopes and sextic algebraic manifolds…

Classical description of quantum randomness using stochastic gauge systems

We present a classical probability model appropriate to the description of quantum randomness. This tool, that we have called stochastic gauge system, constitutes a contextual scheme in which the Kolmogorov probability space depends upon the experimental setup, in accordance with quantum mechanics. Therefore, the probability space behaves like a gauge parameter. We discuss the technical issues of this theory and apply the concept to classically emulate quantum entangled states and even `super-quantum' systems. We exhibit bipartite examples leading to maximum violation of Bell-CHSH inequalities…

贝尔不等式、因果界限与量子贝叶斯计算：统一框架

Bell's Inequality, Causal Bounds, and Quantum Bayesian Computation: A Unified Framework

本文探讨贝尔不等式与因果推理中的因果界限之间的联系，揭示量子贝叶斯计算中的非交换性本质，并提出统一框架。

量子采样的紧致查询下界，及其在认证随机性中的应用

Tight Query Lower Bounds for Quantum Sampling, with an Application to Certified Randomness

该研究证明量子采样中XEB分数超过理想值需Ω(N^{1/3})次查询，并揭示高分数可认证近最优的随机性，为量子优势验证提供紧致下界。

基于单光子的非局域性量子密钥分发与随机数生成方案及其设备无关安全性分析

"Nonlocality-of-a-single-photon" based Quantum Key Distribution and Random Number Generation schemes and their device-independent security analysis

本文提出基于单光子的设备无关量子密钥分发方案，利用非局域性特性实现安全通信，并通过贝尔不等式验证安全性，同时设计基于光子束 splitter 的自测试随机数生成器。