量子相干性量化及其在量子随机数发生器中的应用

Quantum coherence is one of the fundamental differences that distinguish quantum mechanics from classical mechanics. The quantification and the applications of quantum coherence have attracted lots of interests in the physics community. The proposed research grant application mainly contains three aspects. The first part is the quantification of quantum coherence. The proposed research topic starts from the rules of coherence quantification to design quantification methods that satisfy these rules and in the meantime possess operational meanings. The research team will then study the connections between quantum coherence to other quantum correlations, including quantum entanglement and quantum discord. The second part is exploring the connection between quantum coherence and quantum random number generation (QRNG) and the related applications. By breaking the coherence or superposition of a quantum state in the measurement basis, it can be shown that the obtained intrinsic random numbers come from the consumption of coherence. In turn, quantum coherence can be quantified from intrinsic randomness. In modern society, random numbers, especially genuine random numbers, play a crucial role in many fields of science, technology and industry, especially in cryptography, scientific simulations, statistics, and lottery. The research team will quantitatively investigate how quantum coherence can be used as a resource to generate genuine random numbers. The third part is the design and implementation of high-speed QRNGs. Current practical QRNGs are mostly realized in quantum optics and their randomness generation rates are limited by the quantum detection speed. Especially when a QRNG is required to be self-testing, its protocol is usually based on breaking the coherence or entanglement of discrete variables. Continuous-variable QRNGs, on the other hand, use quantum randomness stemmed from continuous variables and may bypass this bottleneck. The research team will focus on the continuous-variable aspect of quantum coherence, to improve the speed and the quality of QRNG.

量子相干性是量子力学区别于经典力学的基本特性。近年来相干性量化及其应用的研究逐渐成为热门课题。本申请项目主要分三个部分。一、量子相干性的量化。申请团队将从相干性量化规则出发，研究和设计满足这些规则同时具有操作意义的量化方式，并研究相干性与量子纠缠、量子失谐等其他量子关联的联系。二、量子相干性与量子随机性的关系及其应用。基于经典力学产生的伪随机数并不适用于安全性要求高的场合，如量子密钥分发。申请团队将定量地研究如何使用量子相干性这种资源来产生真随机数。三、高速的量子随机数发生器的设计和实现。目前，离散变量量子随机数发生器的生成速率主要受制于量子探测速度。特别是要求随机数发生器是自检测时，协议往往是基于破坏离散变量的相干性或者量子纠缠。而基于连续变量的量子随机数发生器，则可以突破探测速度的限制。申请团队着重于量子相干性的重新设计及其在连续变量相关性方面的拓展，来提升随机数发生器的品质和速度。

量子力学是近代物理学最重要的理论之一。量子理论在不同领域的广泛应用，极大推进了科技和社会的进步。量子相干性是量子系统的一个重要特性，是量子力学区别于经典力学的关键因素之一。量子相干性作为一种资源在量子信息处理中起着举足轻重的作用，例如量子随机数发生器、量子密钥分发和量子计算等。对这一资源的度量和操作是量子信息研究中重要的核心内容。研究团队主要在量子相干性的度量，利用量子相干性设计量子随机数产生器，以及设计并且实现实用的量子随机数发生器，证明量子密钥分发安全性等方面进行了理论研究，取得了丰富的成果。.具体来说，研究团队提出并研究了量子相干性的新度量，定量研究了量子态的相干性和量子随机性的联系，通过量子态的相干性刻画了对其进行测量结果的内禀随机性。研究团队还研究了多项式的量子相干性度量，提出了多种量子资源的统一框架理论。为克服测量设备的不完美性，研究团队提出一种新型的测量设备无关量子相干性检验方法，结合实际物理系统，提出了基于激光器自发辐射的随机数发生器设计方案，并与中科大实验团队合作展示了该方案的可行性。量子相干性操作中最重要的问题是转化问题。研究团队提出了量子相干性非渐进条件下的稀释和提纯问题，与美国伊利诺伊大学的Eric Chitambar教授合作，通过多种不同的相干性度量，系统量化了不同非相干操作下的稀释率。该结果对量子随机数产生、量子热力学等领域均有所贡献。另外，我们也可以从量子相干性出发证明量子密钥分发协议的安全性，在实际情况下给出更为简单有效的分析。.研究成果不仅可以帮助我们加深对量子力学随机性本质的理解，利用量子相干性制造的随机数发生器在经济、科学、国防、工业生产等各个领域中都有非常重要的应用。