Contract Signature Using Quantum Information

Quantum Prudent Contracts with Applications to Bitcoin

Smart contracts are cryptographic protocols that are enforced without a judiciary. Smart contracts are used occasionally in Bitcoin and are prevalent in Ethereum. Public quantum money improves upon cash we use today, yet the current constructions do not enable smart contracts. In this work, we define and introduce quantum payment schemes, and show how to implement prudent contracts -- a non-trivial subset of the functionality that a network such as Ethereum provides. Examples discussed include: multi-signature wallets in which funds can be spent by any 2-out-of-3 owners; restricted accounts th…

Contractions, Matrix Paramatrizations, and Quantum Information

In this note, we discuss dilation-theoretic matrix parametrizations of contractions and positive matrices. These parametrizations are then applied to some problems in quantum information theory. First we establish some properties of positive maps, or entanglement witnesses. Two further applications, concerning concrete dilations of completely positive maps, in particular quantum operations, are given.

演化的物理性与统计收缩性是映射的等价概念

Physicality of evolution and statistical contractivity are equivalent notions of maps

本文提出与Chentsov-Petz定理对偶的结果，证明唯一能收缩Fisher信息的线性映射恰为物理映射，表明物理映射与规范统计量度之间无根本层级关系。

条件压缩系数及其在量子网络中的应用

Conditional contraction coefficients and their applications to quantum networks

本研究引入条件压缩系数框架，将经典相对熵与互信息压缩的对应关系扩展至量子边信息场景，为量子网络信息压缩分析提供统一框架，并拓展了相关边界与极限。

$p$波超导体中无能隙拓扑相的纠缠特征

Entanglement signatures of gapless topological phases in a $p$-wave superconductor

本文通过纠缠谱与纠缠熵研究$p$波超导体的无能隙拓扑相，证实无能隙情形下的体-边对应及长程纠缠，并以熵峰标识拓扑量子相变。

Dynamical Aspects of Information Storage in Quantum-Mechanical Systems

We study information storage in noisy quantum registers and computers using the methods of statistical dynamics. We develop the concept of a strictly contractive quantum channel in order to construct mathematical models of physically realizable, i.e., nonideal, quantum registers and computers. Strictly contractive channels are simple enough, yet exhibit very interesting features, which are meaningful from the physical point of view. In particular, they allow us to incorporate the crucial assumption of finite precision of all experimentally realizable operations. Strict contractivity also helps…